Baltic Sea
   HOME

TheInfoList



OR:

The Baltic Sea is an arm of the
Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa ...
that is enclosed by
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
,
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe, Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea, sea across from Sweden, to ...
,
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between ...
,
Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...
,
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called Voivodeships of Poland, voivodeships, covering an area of . Poland has a population of over 38 million and is ...
,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
,
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
and the
North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...
and Central European Plain. The sea stretches from 53°N to 66°N latitude and from 10°E to 30°E longitude. A
marginal sea This is a list of seas of the Ocean#World ocean, World Ocean, including marginal seas, areas of water, various gulfs, bights, bays, and straits. Terminology * Ocean – the four to seven largest named bodies of water in the World Ocean, all o ...
of the Atlantic, with limited water exchange between the two water bodies, the Baltic Sea drains through the
Danish Straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
into the
Kattegat The Kattegat (; sv, Kattegatt ) is a sea area bounded by the Jutlandic peninsula in the west, the Danish Straits islands of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , ...
by way of the
Øresund Øresund or Öresund (, ; da, Øresund ; sv, Öresund ), commonly known in English as the Sound, is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally f ...
,
Great Belt The Great Belt ( da, Storebælt, ) is a strait between the major islands of Zealand (''Sjælland'') and Funen (''Fyn'') in Denmark. It is one of the three Danish straits, Danish Straits. Effectively dividing Denmark in two, the Belt was served ...
and
Little Belt The Little Belt (, ) is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either dir ...
. It includes the
Gulf of Bothnia The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost Arm (geography), arm of the Baltic Sea, between Finland's west coast (Ostrobothnia (historical provinc ...
, the Bay of Bothnia, the
Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
, the
Gulf of Riga The Gulf of Riga, Bay of Riga, or Gulf of Livonia ( lv, Rīgas līcis, et, Liivi laht) is a bay of the Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Polan ...
and the
Bay of Gdańsk A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a Gulf (geography), gulf, sea, sound (geography), sound, or bight (geogra ...
. The " Baltic Proper" is bordered on its northern edge, at latitude 60°N, by
Åland Åland ( fi, Ahvenanmaa: ; ; ) is an Federacy, autonomous and Demilitarized zone, demilitarised region of Finland since 1920 by a decision of the League of Nations. It is the smallest region of Finland by area and population, with a size of 1 ...
and the Gulf of Bothnia, on its northeastern edge by the Gulf of Finland, on its eastern edge by the Gulf of Riga, and in the west by the Swedish part of the southern Scandinavian Peninsula. The Baltic Sea is connected by artificial waterways to the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian language, Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast o ...
via the White Sea–Baltic Canal and to the
German Bight The German Bight (german: Deutsche Bucht; da, tyske bugt; nl, Duitse bocht; fry, Dútske bocht; ; sometimes also the German Bay) is the southeastern bight of the North Sea The North Sea lies between Great Britain, Norway, Denmark, Ger ...
of the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
via the
Kiel Canal The Kiel Canal (german: Nord-Ostsee-Kanal, literally "North- oEast alticSea canal", formerly known as the ) is a long freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water Water (chemical formula ) ...
.


Definitions


Administration

The Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea Area includes the Baltic Sea and the
Kattegat The Kattegat (; sv, Kattegatt ) is a sea area bounded by the Jutlandic peninsula in the west, the Danish Straits islands of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , ...
, without calling Kattegat a part of the Baltic Sea, "For the purposes of this Convention the 'Baltic Sea Area' shall be the Baltic Sea and the Entrance to the Baltic Sea, bounded by the parallel of the Skaw in the Skagerrak at 57°44.43'N."


Traffic history

Historically, the
Kingdom of Denmark The Danish Realm ( da, Danmarks Rige; fo, Danmarkar Ríki; kl, Danmarkip Naalagaaffik), officially the Kingdom of Denmark (; ; ), is a sovereign state located in Northern Europe and Northern North America. It consists of Denmark, metropolitan ...
collected
Sound Dues The Sound Dues (or Sound Tolls; da, Øresundstolden) were a tariff, toll on the use of the Øresund, or "Sound" strait separating the modern day borders of Denmark and Sweden. The tolls constituted up to two thirds of Denmark's state income in th ...
from ships at the border between the ocean and the land-locked Baltic Sea, in tandem: in the
Øresund Øresund or Öresund (, ; da, Øresund ; sv, Öresund ), commonly known in English as the Sound, is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally f ...
at
Kronborg Kronborg is a castle and stronghold in the town of Helsingør, Denmark. Immortalized as Elsinore in William Shakespeare's play ''Hamlet'', Kronborg is one of the most important Renaissance castles in Northern Europe and was inscribed on the UNES ...
castle near Helsingør; in the
Great Belt The Great Belt ( da, Storebælt, ) is a strait between the major islands of Zealand (''Sjælland'') and Funen (''Fyn'') in Denmark. It is one of the three Danish straits, Danish Straits. Effectively dividing Denmark in two, the Belt was served ...
at
Nyborg Nyborg is a city in central Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision ...
; and in the
Little Belt The Little Belt (, ) is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either dir ...
at its narrowest part then
Fredericia Fredericia () is a town located in Fredericia Municipality in the southeastern part of the Jutland peninsula in Denmark. The city is part of the Triangle Region Denmark, Triangle Region, which includes the neighbouring cities of Kolding and Vejl ...
, after that stronghold was built. The narrowest part of Little Belt is the "Middelfart Sund" near Middelfart.


Oceanography

Geographers widely agree that the preferred physical border of the Baltic is a line drawn through the southern Danish islands, Drogden-Sill and Langeland. The Drogden Sill is situated north of Køge Bugt and connects Dragør in the south of
Copenhagen Copenhagen ( or .; da, København ) is the capital and most populous city of Denmark, with a proper population of around 815.000 in the last quarter of 2022; and some 1.370,000 in the urban area; and the wider Copenhagen metropolitan ar ...
to
Malmö Malmö (, ; da, Malmø ) is the largest city in the Counties of Sweden, Swedish county (län) of Skåne County, Scania (Skåne). It is the List of urban areas in Sweden by population, third-largest city in Sweden, after Stockholm and Gothenbur ...
; it is used by the Øresund Bridge, including the ''Drogden Tunnel''. By this definition, the
Danish Straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
is part of the entrance, but the
Bay of Mecklenburg The Bay of Mecklenburg ( or ''Mecklenburgische Bucht''; ), also known as the Mecklenburg Bay or Mecklenburg Bight, is a long narrow basin making up the southwestern finger-like arm of the Baltic Sea, between the shores of Germany to the south a ...
and the Bay of Kiel are parts of the Baltic Sea. Another usual border is the line between Falsterbo, Sweden, and
Stevns Klint Stevns Klint, known as the Cliffs of Stevns in English language, English, is a white chalk cliff located some southeast of Store Heddinge on the Danish island of Zealand. Stretching along the coast, it is of geological importance as one of the ...
, Denmark, as this is the southern border of Øresund. It's also the border between the shallow southern Øresund (with a typical depth of 5–10 meters only) and notably deeper water.


Hydrography and biology

Drogden Sill (depth of ) sets a limit to Øresund and Darss Sill (depth of ), and a limit to the Belt Sea. The shallow sills are obstacles to the flow of heavy salt water from the Kattegat into the basins around
Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , ...
and
Gotland Gotland (, ; ''Gutland'' in Gutnish), also historically spelled Gottland or Gothland (), is Sweden's largest island. It is also a Provinces of Sweden, province, Counties of Sweden, county, Municipalities of Sweden, municipality, and List of dio ...
. The Kattegat and the southwestern Baltic Sea are well oxygenated and have a rich biology. The remainder of the Sea is brackish, poor in oxygen, and in species. Thus, statistically, the more of the entrance that is included in its definition, the healthier the Baltic appears; conversely, the more narrowly it is defined, the more endangered its biology appears.


Etymology and nomenclature

Tacitus Publius Cornelius Tacitus, known simply as Tacitus ( , ; – ), was a Roman historian and politician. Tacitus is widely regarded as one of the greatest Roman historiography, Roman historians by modern scholars. The surviving portions of his t ...
called it ''Mare Suebicum'' after the
Germanic people The Germanic peoples were historical groups of people that once occupied Central Europe and Scandinavia during antiquity and into the early Middle Ages. Since the 19th century, they have traditionally been defined by the use of ancient and ear ...
of the
Suebi The Suebi (or Suebians, also spelled Suevi, Suavi) were a large group of Germanic peoples originally from the Elbe river region in what is now Germany and the Czech Republic. In the early Roman era they included many peoples with their own names ...
, and
Ptolemy Claudius Ptolemy (; grc-gre, wikt:Πτολεμαῖος, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific Treatise, treatis ...
''
Sarmatian The Sarmatians (; grc, Σαρμαται, Sarmatai; Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber ar ...
Ocean'' after the
Sarmatians The Sarmatians (; grc, Σαρμαται, Sarmatai; Latin: ) were a large confederation of Ancient Iranian peoples, ancient Eastern Iranian languages, Eastern Iranian peoples, Iranian Eurasian nomads, equestrian nomadic peoples of classical ant ...
, but the first to name it the ''Baltic Sea'' () was the eleventh-century German chronicler
Adam of Bremen Adam of Bremen ( la, Adamus Bremensis; german: Adam von Bremen) (before 1050 – 12 October 1081/1085) was a German medieval chronicler. He lived and worked in the second half of the eleventh century. Adam is most famous for his chronicle ''Gesta ...
. The origin of the latter name is speculative and it was adopted into Slavic and
Finnic languages The Finnic (''Fennic'') or more precisely Balto-Finnic (Balto-Fennic, Baltic Finnic, Baltic Fennic) languages constitute a branch of the Uralic language family spoken around the Baltic Sea by the Baltic Finnic peoples. There are around 7  ...
spoken around the sea, very likely due to the role of
Medieval Latin Medieval Latin was the form of Literary Latin used in Roman Catholic Church, Roman Catholic Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying deg ...
in
cartography Cartography (; from grc, χάρτης , "papyrus, sheet of paper, map"; and , "write") is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an im ...
. It might be connected to the Germanic word ''belt'', a name used for two of the Danish straits, the Belts, while others claim it to be directly derived from the source of the Germanic word,
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
''balteus'' "belt".Balteus
in ''
Nordisk familjebok ''Nordisk familjebok'' (, "Nordic Family Book") is a Swedish language, Swedish encyclopedia that was published in print from between 1876 and 1993, and that is now fully available in digital form via Project Runeberg at Linköping University. D ...
''.
Adam of Bremen Adam of Bremen ( la, Adamus Bremensis; german: Adam von Bremen) (before 1050 – 12 October 1081/1085) was a German medieval chronicler. He lived and worked in the second half of the eleventh century. Adam is most famous for his chronicle ''Gesta ...
himself compared the sea with a belt, stating that it is so named because it stretches through the land as a belt (''Balticus, eo quod in modum baltei longo tractu per Scithicas regiones tendatur usque in Greciam''). He might also have been influenced by the name of a legendary island mentioned in the ''Natural History'' of
Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman Empire, Roman author, Natural history, naturalist and Natural philosophy, natural philosopher, and naval and army commander of the early Roman Empire, and a friend of t ...
. Pliny mentions an island named '' Baltia'' (or ''Balcia'') with reference to accounts of
Pytheas Pytheas of Massalia (; Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the followin ...
and
Xenophon Xenophon of Athens (; grc, wikt:Ξενοφῶν, Ξενοφῶν ; – probably 355 or 354 BC) was a Greek military leader, philosopher, and historian, born in Athens. At the age of 30, Xenophon was elected commander of one of the biggest Anci ...
. It is possible that Pliny refers to an island named Basilia ("the royal") in ''On the Ocean'' by Pytheas. ''Baltia'' also might be derived from "belt", and therein mean "near belt of sea, strait". Others have suggested that the name of the island originates from the
Proto-Indo-European Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. Its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. No direct record of Proto-Indo-E ...
root ''*bʰel'' meaning "white, fair", which may echo the naming of seas after colours relating to the cardinal points (as per
Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of An ...
and
Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic language, Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''P ...
). This '*bʰel' root and basic meaning were retained in Lithuanian (as ''baltas''), Latvian (as ''balts'') and Slavic (as ''bely''). On this basis, a related hypothesis holds that the name originated from this Indo-European root via a
Baltic language The Baltic languages are a branch of the Indo-European The Indo-European languages are a language family native to the languages of Europe, overwhelming majority of Europe, the Iranian plateau, and the northern Indian subcontinent. Some ...
such as Lithuanian. Another explanation is that, while derived from the aforementioned root, the name of the sea is related to names for various forms of water and related substances in several European languages, that might have been originally associated with colors found in swamps (compare Proto-Slavic '' *bolto'' "swamp"). Yet another explanation is that the name originally meant "enclosed sea, bay" as opposed to open sea. In the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the Post-classical, post-classical period of World history (field), global history. It began with t ...
the sea was known by a variety of names. The name Baltic Sea became dominant only after 1600. Usage of ''Baltic'' and similar terms to denote the region east of the sea started only in the 19th century.


Name in other languages

The Baltic Sea was known in ancient Latin language sources as ''Mare Suebicum'' or even ''Mare Germanicum''. Older native names in languages that used to be spoken on the shores of the sea or near it usually indicate the geographical location of the sea (in Germanic languages), or its size in relation to smaller gulfs (in Old Latvian), or tribes associated with it (in Old Russian the sea was known as the Varanghian Sea). In modern languages, it is known by the equivalents of "East Sea", "West Sea", or "Baltic Sea" in different languages: * "Baltic Sea" is used in Modern English; in the
Baltic languages The Baltic languages are a branch of the Indo-European languages, Indo-European language family spoken natively by a population of about 4.5 million people mainly in areas extending east and southeast of the Baltic Sea in Northern Europe. Toget ...
Latvian (''Baltijas jūra''; in Old Latvian it was referred to as "the Big Sea", while the present day Gulf of Riga was referred to as "the Little Sea") and Lithuanian (''Baltijos jūra''); in
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
(''Mare Balticum'') and the
Romance languages The Romance languages, sometimes referred to as Latin languages or Neo-Latin languages, are the various modern languages that evolved from Vulgar Latin. They are the only extant subgroup of the Italic languages in the Indo-European languages, I ...
French (''Mer Baltique''), Italian (''Mar Baltico''), Portuguese (''Mar Báltico''),
Romanian Romanian may refer to: *anything of, from, or related to the country and nation of Romania **Romanians, an ethnic group **Romanian language, a Romance language ***Romanian dialects, variants of the Romanian language **Romanian cuisine, traditional ...
(''Marea Baltică'') and
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Cana ...
(''Mar Báltico''); in
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
( ''Valtikí Thálassa''); in Albanian (''Deti Balltik''); in Welsh (''Môr Baltig''); in the
Slavic languages The Slavic languages, also known as the Slavonic languages, are Indo-European languages spoken primarily by the Slavs, Slavic peoples and their descendants. They are thought to descend from a proto-language called Proto-Slavic language, Proto ...
Polish (''Morze Bałtyckie'' or ''Bałtyk''), Czech (''Baltské moře'' or ''Balt''), Slovenian (''Baltsko morje''), Bulgarian ( ''Baltijsko More''), Kashubian (''Bôłt''), Macedonian (Балтичко Море ''Baltičko More''), Ukrainian ( ''Baltijs′ke More''), Belarusian (Балтыйскае мора ''Baltyjskaje Mora''), Russian ( ''Baltiyskoye More'') and
Serbo-Croatian Serbo-Croatian () – also called Serbo-Croat (), Serbo-Croat-Bosnian (SCB), Bosnian-Croatian-Serbian (BCS), and Bosnian-Croatian-Montenegrin-Serbian (BCMS) – is a South Slavic languages, South Slavic language and the primary language of Ser ...
(''Baltičko more'' / ); in Hungarian (Balti-tenger). * In
Germanic languages The Germanic languages are a branch of the Indo-European languages, Indo-European language family spoken natively by a population of about 515 million people mainly in Europe, North America, Oceania and Southern Africa. The most widely spoken ...
, except English, "East Sea" is used, as in
Afrikaans Afrikaans (, ) is a West Germanic language that evolved in the Dutch Cape Colony from the Dutch vernacular of Holland proper (i.e., the Hollandic dialect) used by Dutch, French, and German settlers and their slaves. Afrikaans gradually b ...
(''Oossee''), Danish (''Østersøen'' ), Dutch (''Oostzee''), German (''Ostsee''),
Low German : : : : : (70,000) (30,000) (8,000) , familycolor = Indo-European , fam2 = Germanic , fam3 = West Germanic , fam4 = North Sea Germanic , ancestor = Old Saxon Old Saxon, also known as ...
''(Oostsee)'', Icelandic and Faroese (''Eystrasalt''), Norwegian ( Bokmål: ''Østersjøen'' ;
Nynorsk Nynorsk () () is one of the two written standards of the Norwegian language Norwegian ( no, norsk, links=no ) is a North Germanic languages, North Germanic language spoken mainly in Norway, where it is an official language. Along with Swed ...
: ''Austersjøen''), and Swedish (''Östersjön''). In
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language English is a West Germanic languages, West Germanic language of the Indo-European language family, with its earliest forms spoken by the inhabita ...
it was known as ''Ostsǣ''; also in Hungarian the former name was ''Keleti-tenger'' ("East-sea", due to German influence). In addition, Finnish, a Finnic language, uses the term ''Itämeri'' "East Sea", possibly a
calque In linguistics, a calque () or loan translation is a word or phrase borrowed from another language by literal translation, literal word-for-word or root-for-root translation. When used as a verb, "to calque" means to borrow a word or phrase from ...
from a Germanic language. As the Baltic is not particularly eastward in relation to Finland, the use of this term may be a leftover from the period of Swedish rule. * In another Finnic language, Estonian, it is called the "West Sea" (''Läänemeri''), with the correct geography (the sea is west of Estonia). In South Estonian, it has the meaning of both "West Sea" and "Evening Sea" (''Õdagumeri'').


History


Classical world

At the time of the
Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Roman Republic, Republican period of ancient Rome. As a polity, it included large territorial holdings aro ...
, the Baltic Sea was known as the ''Mare Suebicum'' or ''Mare Sarmaticum''.
Tacitus Publius Cornelius Tacitus, known simply as Tacitus ( , ; – ), was a Roman historian and politician. Tacitus is widely regarded as one of the greatest Roman historiography, Roman historians by modern scholars. The surviving portions of his t ...
in his AD 98 ''Agricola'' and ''Germania'' described the Mare Suebicum, named for the
Suebi The Suebi (or Suebians, also spelled Suevi, Suavi) were a large group of Germanic peoples originally from the Elbe river region in what is now Germany and the Czech Republic. In the early Roman era they included many peoples with their own names ...
tribe, during the spring months, as a
brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...
sea where the ice broke apart and chunks floated about. The Suebi eventually migrated southwest to temporarily reside in the Rhineland area of modern Germany, where their name survives in the historic region known as
Swabia Swabia ; german: Schwaben , colloquially ''Schwabenland'' or ''Ländle''; archaic English also Suabia or Svebia is a cultural, Historical region, historic and linguistic region in southwestern Germany. The name is ultimately derived from the ...
.
Jordanes Jordanes (), also written as Jordanis or Jornandes, was a 6th-century Eastern Roman bureaucrat widely believed to be of Goths, Gothic descent who became a historian later in life. Late in life he wrote two works, one on Roman history (''Romana ...
called it the ''Germanic Sea'' in his work, the ''
Getica ''De origine actibusque Getarum'' (''The Origin and Deeds of the Getae oths'), commonly abbreviated ''Getica'', written in Late Latin Late Latin ( la, Latinitas serior) is the scholarly name for the form of Literary Latin of late antiquity. ...
''.


Middle Ages

In the early
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the Post-classical, post-classical period of World history (field), global history. It began with t ...
, Norse (Scandinavian) merchants built a trade empire all around the Baltic. Later, the Norse fought for control of the Baltic against Wendish tribes dwelling on the southern shore. The Norse also used the rivers of
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
for trade routes, finding their way eventually to the
Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of An ...
and southern Russia. This Norse-dominated period is referred to as the
Viking Age The Viking Age () was the period during the Middle Ages when Norsemen known as Vikings undertook large-scale raiding, colonizing, conquest, and trading throughout Europe and reached North America. It followed the Migration Period and the Germ ...
. Since the
Viking Age The Viking Age () was the period during the Middle Ages when Norsemen known as Vikings undertook large-scale raiding, colonizing, conquest, and trading throughout Europe and reached North America. It followed the Migration Period and the Germ ...
, the Scandinavians have referred to the Baltic Sea as ''Austmarr'' ("Eastern Lake"). "Eastern Sea", appears in the ''
Heimskringla ''Heimskringla'' () is the best known of the Old Norse kings' sagas. It was written in Old Norse in Iceland by the poet and historian Snorre Sturlason (1178/79–1241) 1230. The name ''Heimskringla'' was first used in the 17th century, derived ...
'' and ''Eystra salt'' appears in '' Sörla þáttr''.
Saxo Grammaticus Saxo Grammaticus (c. 1150 – c. 1220), also known as Saxo cognomine Longus, was a Danish people, Danish historian, theologian and author. He is thought to have been a clerk or secretary to Absalon, Archbishop of Lund, the main advisor to Valdemar ...
recorded in ''
Gesta Danorum ''Gesta Danorum'' ("Deeds of the Danes") is a patriotic work of Danish history, by the 12th-century author Saxo Grammaticus ("Saxo the Literate", literally "the Grammarian"). It is the most ambitious literary undertaking of History of Denmark#M ...
'' an older name, '' Gandvik'', ''-vik'' being
Old Norse Old Norse, Old Nordic, or Old Scandinavian, is a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia and t ...
for "bay", which implies that the Vikings correctly regarded it as an inlet of the sea. Another form of the name, "Grandvik", attested in at least one English translation of ''Gesta Danorum'', is likely to be a misspelling. In addition to fish the sea also provides
amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Ma ...
, especially from its southern shores within today's borders of
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called Voivodeships of Poland, voivodeships, covering an area of . Poland has a population of over 38 million and is ...
,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
and
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
. First mentions of amber deposits on the South Coast of the Baltic Sea date back to the 12th century. The bordering countries have also traditionally exported lumber,
wood tar Tar is a dark brown or black viscosity, viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic matter, organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. ...
,
flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in W ...
,
hemp Hemp, or industrial hemp, is a botanical class of ''Cannabis sativa'' cultivars grown specifically for industrial or medicinal use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants o ...
and furs by ship across the Baltic. Sweden had from early medieval times exported
iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
and
silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
mined there, while Poland had and still has extensive
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in the form of a natural crystallinity, crystalline mineral is known as rock salt or halite. ...
mines. Thus, the Baltic Sea has long been crossed by much merchant shipping. The lands on the Baltic's eastern shore were among the last in Europe to be converted to
Christianity Christianity is an Abrahamic religions, Abrahamic Monotheism, monotheistic religion based on the Life of Jesus in the New Testament, life and Teachings of Jesus, teachings of Jesus, Jesus of Nazareth. It is the Major religious groups, world's ...
. This finally happened during the
Northern Crusades The Northern Crusades or Baltic Crusades were Christianity and colonialism, Christian colonization and Christianization campaigns undertaken by Catholic Church, Catholic Christian Military order (society), military orders and kingdoms, primarily ...
:
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
in the twelfth century by Swedes, and what are now
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe, Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea, sea across from Sweden, to ...
and
Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...
in the early thirteenth century by Danes and Germans (
Livonian Brothers of the Sword The Livonian Brothers of the Sword ( la, Fratres militiæ Christi Livoniae, german: Schwertbrüderorden) was a Catholic Church, Catholic Military order (monastic society), military order established in 1202 during the Livonian Crusade by Albert of ...
). The
Teutonic Order The Order of Brothers of the German House of Saint Mary in Jerusalem, commonly known as the Teutonic Order, is a religious order (Catholic), Catholic religious institution founded as a military order (religious society), military society in ...
gained control over parts of the southern and eastern shore of the Baltic Sea, where they set up their monastic state.
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
was the last European state to convert to Christianity.


An arena of conflict

In the period between the 8th and 14th centuries, there was much piracy in the Baltic from the coasts of
Pomerania Pomerania ( pl, Pomorze; german: Pommern; Kashubian: ''Pòmòrskô''; sv, Pommern) is a historical region on the southern shore of the Baltic Sea in Central Europe, split between Poland and Germany. The western part of Pomerania belongs to ...
and
Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a Germans, German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved ...
, and the
Victual Brothers , native_name_lang = , named_after = french: vitailleurs (provisioners, Hundred Years' War) , image = Vitalienbrueder, Wandmalerei in d, Kirche zu Bunge auf Gotland, gemalt ca. 1405.JPG , image_size = 250p ...
held
Gotland Gotland (, ; ''Gutland'' in Gutnish), also historically spelled Gottland or Gothland (), is Sweden's largest island. It is also a Provinces of Sweden, province, Counties of Sweden, county, Municipalities of Sweden, municipality, and List of dio ...
. Starting in the 11th century, the southern and eastern shores of the Baltic were settled by migrants mainly from
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between ...
, a movement called the ''
Ostsiedlung (, literally "East-settling") is the term for the Early Middle Ages, Early Medieval and High Middle Ages, High Medieval migration-period when ethnic Germans moved into the territories in the eastern part of Francia, East Francia, and the Hol ...
'' ("east settling"). Other settlers were from the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Neth ...
,
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
, and
Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...
. The
Polabian Slavs Polabian Slavs ( dsb, Połobske słowjany, pl, Słowianie połabscy, cz, Polabští slované) is a collective term applied to a number of Lechites, Lechitic (West Slavs, West Slavic) tribes who lived scattered along the Elbe river in what is ...
were gradually assimilated by the Germans.
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
gradually gained control over most of the Baltic coast, until she lost much of her possessions after being defeated in the 1227 Battle of Bornhöved. In the 13th to 16th centuries, the strongest economic force in Northern Europe was the
Hanseatic League The Hanseatic League (; gml, Hanse, , ; german: label=German language, Modern German, Deutsche Hanse) was a Middle Ages, medieval commercial and defensive confederation of merchant guilds and market towns in Central Europe, Central and Norther ...
, a federation of merchant cities around the Baltic Sea and the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
. In the sixteenth and early seventeenth centuries,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called Voivodeships of Poland, voivodeships, covering an area of . Poland has a population of over 38 million and is ...
,
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
, and
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
fought wars for '' Dominium maris baltici'' ("Lordship over the Baltic Sea"). Eventually, it was Sweden that virtually encompassed the Baltic Sea. In Sweden, the sea was then referred to as ''Mare Nostrum Balticum'' ("Our Baltic Sea"). The goal of Swedish warfare during the 17th century was to make the Baltic Sea an all-Swedish sea (''Ett Svenskt innanhav''), something that was accomplished except the part between Riga in Latvia and
Stettin Szczecin (, , german: Stettin ; sv, Stettin ; Latin language, Latin: ''Sedinum'' or ''Stetinum'') is the capital city, capital and largest city of the West Pomeranian Voivodeship in northwestern Poland. Located near the Baltic Sea and the Po ...
in Pomerania. However, the Dutch dominated the Baltic trade in the seventeenth century. In the eighteenth century,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
and
Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a Germans, German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved ...
became the leading powers over the sea. Sweden's defeat in the
Great Northern War The Great Northern War (1700–1721) was a conflict in which a coalition led by the Tsardom of Russia successfully contested the supremacy of the Swedish Empire in Northern Europe, Northern, Central Europe, Central and Eastern Europe. The i ...
brought Russia to the eastern coast. Russia became and remained a dominating power in the Baltic. Russia's
Peter the Great Peter I ( – ), most commonly known as Peter the Great,) or Pyotr Alekséyevich ( rus, Пётр Алексе́евич, p=ˈpʲɵtr ɐlʲɪˈksʲejɪvʲɪtɕ, , group=pron was a List of Russian monarchs, Russian monarch who ruled the ...
saw the strategic importance of the Baltic and decided to found his new capital,
Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...
, at the mouth of the
Neva The Neva (russian: Нева́, ) is a river in northwestern Russia flowing from Lake Ladoga through the western part of Leningrad Oblast (historical region of Ingria) to the Neva Bay of the Gulf of Finland. Despite its modest length of , it is ...
river at the east end of the
Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
. There was much trading not just within the Baltic region but also with the North Sea region, especially eastern
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separa ...
and the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Neth ...
: their fleets needed the Baltic timber, tar, flax, and hemp. During the
Crimean War The Crimean War, , was fought from October 1853 to February 1856 between Russian Empire, Russia and an ultimately victorious alliance of the Ottoman Empire, Second French Empire, France, the United Kingdom of Great Britain and Ireland, Uni ...
, a joint British and French fleet attacked the Russian fortresses in the Baltic; the case is also known as the Åland War. They bombarded Sveaborg, which guards
Helsinki Helsinki ( or ; ; sv, Helsingfors, ) is the Capital city, capital, primate city, primate, and List of cities and towns in Finland, most populous city of Finland. Located on the shore of the Gulf of Finland, it is the seat of the region of U ...
; and
Kronstadt Kronstadt (russian: Кроншта́дт, Kronshtadt ), also spelled Kronshtadt, Cronstadt or Kronštádt (from german: link=no, Krone for "crown (headgear), crown" and ''Stadt'' for "city") is a Russian administrative divisions of Saint Petersb ...
, which guards Saint Petersburg; and they destroyed Bomarsund in
Åland Åland ( fi, Ahvenanmaa: ; ; ) is an Federacy, autonomous and Demilitarized zone, demilitarised region of Finland since 1920 by a decision of the League of Nations. It is the smallest region of Finland by area and population, with a size of 1 ...
. After the unification of
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between ...
in 1871, the whole southern coast became German.
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
was partly fought in the Baltic Sea. After 1920
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called Voivodeships of Poland, voivodeships, covering an area of . Poland has a population of over 38 million and is ...
was granted access to the Baltic Sea at the expense of Germany by the
Polish Corridor The Polish Corridor (german: Polnischer Korridor; pl, Pomorze, Polski Korytarz), also known as the Danzig Corridor, Corridor to the Sea or Gdańsk Corridor, was a territory located in the region of Pomerelia (Pomeranian Voivodeship (1919– ...
and enlarged the port of
Gdynia Gdynia ( ; ; german: Gdingen (currently), (1939–1945); csb, Gdiniô, , , ) is a city in northern Poland and a seaport on the Baltic Sea coast. With a population of 243,918, it is the List of cities in Poland, 12th-largest city in Poland and ...
in rivalry with the port of the
Free City of Danzig The Free City of Danzig (german: Freie Stadt Danzig; pl, Wolne Miasto Gdańsk; csb, Wòlny Gard Gduńsk) was a city-state under the protection of the League of Nations between 1920 and 1939, consisting of the Baltic Sea port of Danzig (now Gda ...
. After the Nazis' rise to power, Germany reclaimed the Memelland and after the outbreak of the
Eastern Front (World War II) The Eastern Front of World War II was a Theater (warfare), theatre of conflict between the European Axis powers against the Soviet Union (USSR), Polish Armed Forces in the East, Poland and other Allies of World War II, Allies, which encom ...
occupied the Baltic states. In 1945, the Baltic Sea became a mass grave for retreating soldiers and refugees on torpedoed troop transports. The sinking of the '' Wilhelm Gustloff'' remains the worst maritime disaster in history, killing (very roughly) 9,000 people. In 2005, a Russian group of scientists found over five thousand airplane wrecks, sunken warships, and other material, mainly from World War II, on the bottom of the sea.


Since World War II

Since the end of
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, various nations, including the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
, the United Kingdom and the United States have disposed of
chemical weapons A chemical weapon (CW) is a specialized Ammunition, munition that uses chemicals chemical engineering, formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be an ...
in the Baltic Sea, raising concerns of environmental contamination. Today, fishermen occasionally find some of these materials: the most recent available report from the Helsinki Commission notes that four small scale catches of chemical munitions representing approximately of material were reported in 2005. This is a reduction from the 25 incidents representing of material in 2003. Until now, the U.S. Government refuses to disclose the exact coordinates of the wreck sites. Deteriorating bottles leak
mustard gas Mustard gas or sulfur mustard is a chemical compound belonging to a family of cytotoxicity, cytotoxic and blister agents known as mustard agents. The name ''mustard gas'' is technically incorrect: the substance, when Dispersion (chemistry), disp ...
and other substances, thus slowly poisoning a substantial part of the Baltic Sea. After 1945, the German population was expelled from all areas east of the Oder-Neisse line, making room for new Polish and Russian settlement. Poland gained most of the southern shore. The Soviet Union gained another access to the Baltic with the
Kaliningrad Oblast Kaliningrad Oblast (russian: Калинингра́дская о́бласть, translit=Kaliningradskaya oblast') is the westernmost federal subjects of Russia, federal subject of Russia. It is a Enclave and exclave, semi-exclave situated o ...
, that had been part of German-settled
East Prussia East Prussia ; german: Ostpreißen, label=Low Prussian dialect, Low Prussian; pl, Prusy Wschodnie; lt, Rytų Prūsija was a Provinces of Prussia, province of the Kingdom of Prussia from 1773 to 1829 and again from 1878 (with the Kingdom itse ...
. The Baltic states on the eastern shore were annexed by the Soviet Union. The Baltic then separated opposing military blocs:
NATO The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental military alliance between 30 Member sta ...
and the
Warsaw Pact The Warsaw Pact (WP) or Treaty of Warsaw, formally the Treaty of Friendship, Cooperation and Mutual Assistance, was a Collective security#Collective defense, collective defense treaty signed in Warsaw, Polish People's Republic, Poland, between ...
. Neutral Sweden developed incident weapons to defend its
territorial waters The term territorial waters is sometimes used informally to refer to any area of water over which a sovereign state has jurisdiction, including internal waters, the #Territorial sea, territorial sea, the #Contiguous zone, contiguous zone, the e ...
after the Swedish submarine incidents. This border status restricted trade and travel. It ended only after the collapse of the
Communist Communism (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around ...
regimes in Central and Eastern Europe in the late 1980s. Since May 2004, with the accession of the Baltic states and Poland, the Baltic Sea has been almost entirely surrounded by countries of the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
(EU). The remaining non-EU shore areas are Russian: the Saint Petersburg area and the
Kaliningrad Oblast Kaliningrad Oblast (russian: Калинингра́дская о́бласть, translit=Kaliningradskaya oblast') is the westernmost federal subjects of Russia, federal subject of Russia. It is a Enclave and exclave, semi-exclave situated o ...
exclave An enclave is a territory (or a small territory apart of a larger one) that is entirely surrounded by the territory of one other state or entity. Enclaves may also exist within territorial waters. ''Enclave'' is sometimes used improperly to deno ...
. Winter storms begin arriving in the region during October. These have caused numerous
shipwreck A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...
s, and contributed to the extreme difficulties of rescuing passengers of the ferry '' M/S Estonia'' en route from
Tallinn Tallinn () is the most populous and capital city of Estonia. Situated on a Tallinn Bay, bay in north Estonia, on the shore of the Gulf of Finland of the Baltic Sea, Tallinn has a population of 437,811 (as of 2022) and administratively lies in t ...
, Estonia, to
Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...
, Sweden, in September 1994, which claimed the lives of 852 people. Older, wood-based shipwrecks such as the '' Vasa'' tend to remain well-preserved, as the Baltic's cold and brackish water does not suit the
shipworm The shipworms are marine bivalve molluscs in the family Teredinidae: a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into (and commonly eventually destroying) wood that is immersed in sea water, including ...
.


Storm floods

Storm surge A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low pressure area, low-pressure weather systems, such as cyclones. It is measured as the rise in water ...
floods are generally taken to occur when the water level is more than one metre above normal. In Warnemünde about 110 floods occurred from 1950 to 2000, an average of just over two per year. Historic flood events were the All Saints' Flood of 1304 and other floods in the years 1320, 1449, 1625, 1694, 1784 and 1825. Little is known of their extent. From 1872, there exist regular and reliable records of water levels in the Baltic Sea. The highest was the flood of 1872 when the water was an average of above sea level at Warnemünde and a maximum of above sea level in Warnemünde. In the last very heavy floods the average water levels reached above sea level in 1904, in 1913, in January 1954, on 2–4 November 1995 and on 21 February 2002.


Geography


Geophysical data

An arm of the
North Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...
, the Baltic Sea is enclosed by
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
and
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
to the west,
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
to the northeast, and the
Baltic countries The Baltic states, et, Balti riigid or the Baltic countries is a geopolitical term, which currently is used to group three countries: Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Euro ...
to the southeast. It is about long, an average of wide, and an average of deep. The maximum depth is which is on the Swedish side of the center. The surface area is about and the volume is about . The periphery amounts to about of coastline. The Baltic Sea is one of the largest
brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...
inland seas by area, and occupies a basin (a ''
Zungenbecken A ''Zungenbecken'', also called a tongue basin or tongue-basin, is part of a succession of ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of cont ...
'') formed by glacial erosion during the last few
ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and Green ...
s.


Extent

The
International Hydrographic Organization The International Hydrographic Organization (IHO) is an intergovernmental organisation representing hydrography. , the IHO comprised 98 Member States. A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters a ...
defines the limits of the Baltic Sea as follows: :Bordered by the coasts of Germany, Denmark, Poland, Sweden, Finland, Russia, Estonia, Latvia, and Lithuania, it extends north-eastward of the following limits: :*''In the
Little Belt The Little Belt (, ) is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either dir ...
.'' A line joining Falshöft () and Vejsnæs Nakke ( Ærø: ). :*''In the
Great Belt The Great Belt ( da, Storebælt, ) is a strait between the major islands of Zealand (''Sjælland'') and Funen (''Fyn'') in Denmark. It is one of the three Danish straits, Danish Straits. Effectively dividing Denmark in two, the Belt was served ...
.'' A line joining Gulstav (South extreme of Langeland Island) and Kappel Kirke () on Island of
Lolland Lolland (; formerly spelled ''Laaland'', literally "low land") is the fourth largest island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands su ...
. :*''In the Guldborg Sound.'' A line joining Flinthorne-Rev and Skjelby (). :*''In the Sound.'' A line joining Stevns Lighthouse () and Falsterbo Point ().


Subdivisions

The northern part of the Baltic Sea is known as the
Gulf of Bothnia The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost Arm (geography), arm of the Baltic Sea, between Finland's west coast (Ostrobothnia (historical provinc ...
, of which the northernmost part is the Bay of Bothnia or
Bothnian Bay The Bothnian Bay or Bay of Bothnia (; ) is the northernmost part of the Gulf of Bothnia, which is in turn the northern part of the Baltic Sea. The land holding the bay is Post-glacial rebound, still rising after the weight of ice-age glaciers has ...
. The more rounded southern basin of the gulf is called Bothnian Sea and immediately to the south of it lies the
Sea of Åland The Åland Sea (or the Sea of Åland; sv, Ålands hav, fi, Ahvenanmeri) is a waterway A waterway is any Navigability, navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importa ...
. The
Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
connects the Baltic Sea with
Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...
. The
Gulf of Riga The Gulf of Riga, Bay of Riga, or Gulf of Livonia ( lv, Rīgas līcis, et, Liivi laht) is a bay of the Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Polan ...
lies between the
Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...
n capital city of
Riga Riga (; lv, Rīga , liv, Rīgõ) is the capital and largest city of Latvia and is home to 605,802 inhabitants which is a third of Latvia's population. The city lies on the Gulf of Riga at the mouth of the Daugava (river), Daugava river where ...
and the
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe, Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea, sea across from Sweden, to ...
n island of
Saaremaa Saaremaa is the largest island in Estonia, measuring . The main island of Saare County, it is located in the Baltic Sea, south of Hiiumaa island and west of Muhu island, and belongs to the West Estonian Archipelago. The capital of the island i ...
. The Northern Baltic Sea lies between the
Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...
area, southwestern Finland, and Estonia. The Western and Eastern Gotland basins form the major parts of the Central Baltic Sea or Baltic proper. The
Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , ...
Basin is the area east of Bornholm, and the shallower Arkona Basin extends from Bornholm to the Danish isles of
Falster Falster () is an island in south-eastern Denmark with an area of and 43,398 inhabitants as of 1 January 2010.
and
Zealand Zealand ( da, Sjælland ) at 7,031 km2 is the largest and most populous islands of Denmark, island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size). Zealand had a population of 2,319,705 on 1 January ...
. In the south, the
Bay of Gdańsk A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a Gulf (geography), gulf, sea, sound (geography), sound, or bight (geogra ...
lies east of the
Hel Peninsula Hel Peninsula (; pl, Mierzeja Helska, Półwysep Helski; csb, Hélskô Sztremlëzna; german: Halbinsel Hela or ''Putziger Spit (landform), Nehrung'') is a sand bar peninsula in northern Poland separating the Bay of Puck from the open Balti ...
on the Polish coast and west of the
Sambia Peninsula Sambia (russian: Самбийский полуостров, lit=Sambian Peninsula, translit=Sambiysky poluostrov) or Samland (russian: Земландский полуостров, lit=Zemlandic Peninsula, translit=Zemlandsky poluostrov) or Kalini ...
in
Kaliningrad Oblast Kaliningrad Oblast (russian: Калинингра́дская о́бласть, translit=Kaliningradskaya oblast') is the westernmost federal subjects of Russia, federal subject of Russia. It is a Enclave and exclave, semi-exclave situated o ...
. The
Bay of Pomerania The Bay of Pomerania ( pl, Zatoka Pomorska; german: Pommersche Bucht; csb, Pòmòrskô Hôwinga) is a basin in the southwestern Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, ...
lies north of the islands of Usedom/Uznam and
Wolin Wolin (; formerly german: Wollin ) is the name both of a Poland, Polish island in the Baltic Sea, just off the Polish coast, and a Wolin, Poland, town on that island. Administratively, the island belongs to the West Pomeranian Voivodeship. Woli ...
, east of
Rügen Rügen (; la, Rugia, ) is Germany's largest List of German islands, island. It is located off the Pomeranian coast in the Baltic Sea and belongs to the state of Mecklenburg-Western Pomerania. The "gateway" to Rügen island is the Hanseatic c ...
. Between Falster and the German coast lie the
Bay of Mecklenburg The Bay of Mecklenburg ( or ''Mecklenburgische Bucht''; ), also known as the Mecklenburg Bay or Mecklenburg Bight, is a long narrow basin making up the southwestern finger-like arm of the Baltic Sea, between the shores of Germany to the south a ...
and Bay of Lübeck. The westernmost part of the Baltic Sea is the Bay of Kiel. The three
Danish straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
, the
Great Belt The Great Belt ( da, Storebælt, ) is a strait between the major islands of Zealand (''Sjælland'') and Funen (''Fyn'') in Denmark. It is one of the three Danish straits, Danish Straits. Effectively dividing Denmark in two, the Belt was served ...
, the
Little Belt The Little Belt (, ) is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either dir ...
and The Sound (''Öresund''/''Øresund''), connect the Baltic Sea with the
Kattegat The Kattegat (; sv, Kattegatt ) is a sea area bounded by the Jutlandic peninsula in the west, the Danish Straits islands of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , ...
and
Skagerrak The Skagerrak (, , ) is a strait running between the Jutland, Jutland peninsula of Denmark, the southeast coast of Norway and the west coast of Sweden, connecting the North Sea and the Kattegat sea area through the Danish Straits to the Baltic S ...
strait in the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
.


Temperature and ice

The water temperature of the Baltic Sea varies significantly depending on exact location, season and depth. At the Bornholm Basin, which is located directly east of the island of the same name, the surface temperature typically falls to during the peak of the winter and rises to during the peak of the summer, with an annual average of around . A similar pattern can be seen in the Gotland Basin, which is located between the island of Gotland and Latvia. In the deep of these basins the temperature variations are smaller. At the bottom of the Bornholm Basin, deeper than , the temperature typically is , and at the bottom of the Gotland Basin, at depths greater than , the temperature typically is . Generally, offshore locations, lower latitudes and islands maintain
maritime climate An oceanic climate, also known as a marine climate, is the humid temperate climate sub-type in Köppen climate classification, Köppen classification ''Cfb'', typical of west coasts in higher middle latitudes of continents, generally featuring ...
s, but adjacent to the water
continental climate Continental climates often have a significant annual variation in temperature (warm summers and cold winters). They tend to occur in the middle latitudes (40 to 55 north), within large landmasses where prevailing winds blow overland bringing som ...
s are common, especially on the
Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
. In the northern tributaries the climates transition from moderate continental to
subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of Hemiboreal, humid continental regions and covering much of Alaska, Canada, Iceland, the north of Scandinavia, Siberia, and the Cairngorms ...
on the northernmost coastlines. On the long-term average, the Baltic Sea is ice-covered at the annual maximum for about 45% of its surface area. The ice-covered area during such a typical winter includes the
Gulf of Bothnia The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost Arm (geography), arm of the Baltic Sea, between Finland's west coast (Ostrobothnia (historical provinc ...
, the
Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
, the
Gulf of Riga The Gulf of Riga, Bay of Riga, or Gulf of Livonia ( lv, Rīgas līcis, et, Liivi laht) is a bay of the Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Polan ...
, the archipelago west of Estonia, the Stockholm archipelago, and the
Archipelago Sea The Archipelago Sea ( fi, Saaristomeri, sv, Skärgårdshavet) is a part of the Baltic Sea between the Gulf of Bothnia, the Gulf of Finland and the Sea of Åland, within Finnish territorial waters. By some definitions it contains the largest ...
southwest of Finland. The remainder of the Baltic does not freeze during a normal winter, except sheltered bays and shallow lagoons such as the
Curonian Lagoon The Curonian Lagoon (or Bay, Gulf; russian: Куршский залив, lt, Kuršių marios, pl, Zalew Kuroński, german: Kurisches Haff, lv, Kuršu joma) is a freshwater Fresh water or freshwater is any naturally occurring liquid or f ...
. The ice reaches its maximum extent in February or March; typical ice thickness in the northernmost areas in the
Bothnian Bay The Bothnian Bay or Bay of Bothnia (; ) is the northernmost part of the Gulf of Bothnia, which is in turn the northern part of the Baltic Sea. The land holding the bay is Post-glacial rebound, still rising after the weight of ice-age glaciers has ...
, the northern basin of the Gulf of Bothnia, is about for landfast sea ice. The thickness decreases farther south. Freezing begins in the northern extremities of the Gulf of Bothnia typically in the middle of November, reaching the open waters of the Bothnian Bay in early January. The Bothnian Sea, the basin south of
Kvarken Kvarken ( sv, Kvarken, Norra Kvarken (as opposed to South Kvarken); ) is the narrow region of the Gulf of Bothnia separating the Bothnian Bay (the inner part of the gulf) from the Bothnian Sea. The distance from the Sweden, Swedish mainland to th ...
, freezes on average in late February. The Gulf of Finland and the Gulf of Riga freeze typically in late January. In 2011, the Gulf of Finland was completely frozen on 15 February. The ice extent depends on whether the winter is mild, moderate, or severe. In severe winters ice can form around southern
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
and even in the
Danish straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
. According to the 18th-century natural historian
William Derham William Derham FRS (26 November 16575 April 1735)Smolenaars, Marja.Derham, William (1657–1735), '' Oxford Dictionary of National Biography'', Oxford University Press, 2004. Accessed 26 May 2007. was an English clergyman, natural theologian, ...
, during the severe winters of 1703 and 1708, the ice cover reached as far as the Danish straits. Frequently, parts of the Gulf of Bothnia and the Gulf of Finland are frozen, in addition to coastal fringes in more southerly locations such as the Gulf of Riga. This description meant that the whole of the Baltic Sea was covered with ice. Since 1720, the Baltic Sea has frozen over entirely 20 times, most recently in early 1987, which was the most severe winter in Scandinavia since 1720. The ice then covered . During the winter of 2010–11, which was quite severe compared to those of the last decades, the maximum ice cover was , which was reached on 25 February 2011. The ice then extended from the north down to the northern tip of
Gotland Gotland (, ; ''Gutland'' in Gutnish), also historically spelled Gottland or Gothland (), is Sweden's largest island. It is also a Provinces of Sweden, province, Counties of Sweden, county, Municipalities of Sweden, municipality, and List of dio ...
, with small ice-free areas on either side, and the east coast of the Baltic Sea was covered by an ice sheet about wide all the way to
Gdańsk Gdańsk ( , also ; ; csb, Gduńsk;Stefan Ramułt, ''Słownik języka pomorskiego, czyli kaszubskiego'', Kraków 1893, Gdańsk 2003, ISBN 83-87408-64-6. , Johann Georg Theodor Grässe, ''Orbis latinus oder Verzeichniss der lateinischen Benen ...
. This was brought about by a stagnant
high-pressure area A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are Mesoscale meteorology , middle-scale meteorological features t ...
that lingered over central and northern Scandinavia from around 10 to 24 February. After this, strong southern winds pushed the ice further into the north, and much of the waters north of Gotland were again free of ice, which had then packed against the shores of southern Finland. The effects of the afore-mentioned high-pressure area did not reach the southern parts of the Baltic Sea, and thus the entire sea did not freeze over. However, floating ice was additionally observed near Świnoujście harbor in January 2010. In recent years before 2011, the Bothnian Bay and the Bothnian Sea were frozen with solid ice near the Baltic coast and dense floating ice far from it. In 2008, almost no ice formed except for a short period in March. During winter,
fast ice Fast ice (also called ''land-fast ice'', ''landfast ice'', and ''shore-fast ice'') is sea ice that is "fastened" to the coastline, to the sea floor along shoals or to grounded icebergs.Leppäranta, M. 2011. The Drift of Sea Ice. Berlin: Springer- ...
, which is attached to the shoreline, develops first, rendering ports unusable without the services of
icebreaker An icebreaker is a special-purpose ship or boat designed to move and Ice navigation, navigate through ice-covered waters, and provide safe waterways for other boats and ships. Although the term usually refers to ice-breaking ships, it may also r ...
s. Level ice, ice sludge,
pancake ice Pancake ice is a form of sea ice that consists of round pieces of ice with diameters ranging from 30 centimetres (12 in) to 3 metres (9.8 ft) and thicknesses up to 10 centimetres (3.9 inches), depending on the local conditions. It forms as a resu ...
, and rafter ice form in the more open regions. The gleaming expanse of ice is similar to the
Arctic The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenland), northern Finland ...
, with wind-driven pack ice and ridges up to . Offshore of the landfast ice, the ice remains very dynamic all year, and it is relatively easily moved around by winds and therefore forms
pack ice Drift ice, also called brash ice, is sea ice that is not attached to the shoreline or any other fixed object (shoals, grounded icebergs, etc.).Leppäranta, M. 2011. The Drift of Sea Ice. Berlin: Springer-Verlag. Unlike fast ice, which is "fastene ...
, made up of large piles and ridges pushed against the landfast ice and shores. In spring, the Gulf of Finland and the Gulf of Bothnia normally thaw in late April, with some ice ridges persisting until May in the eastern extremities of the Gulf of Finland. In the northernmost reaches of the Bothnian Bay, ice usually stays until late May; by early June it is practically always gone. However, in the famine year of
1867 Events January–March * January 1 – The John A. Roebling Suspension Bridge, Covington–Cincinnati Suspension Bridge opens between Cincinnati, Ohio, and Covington, Kentucky, in the United States, becoming the longest single-span br ...
remnants of ice were observed as late as 17 July near Uddskär. Even as far south as
Øresund Øresund or Öresund (, ; da, Øresund ; sv, Öresund ), commonly known in English as the Sound, is a strait A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally f ...
, remnants of ice have been observed in May on several occasions; near Taarbaek on 15 May 1942 and near Copenhagen on 11 May 1771. Drift ice was also observed on 11 May 1799. The ice cover is the main habitat for two large mammals, the
grey seal The grey seal (''Halichoerus grypus'') is found on both shores of the North Atlantic Ocean. In Latin Halichoerus grypus means "hook-nosed sea pig". It is a large pinniped, seal of the family (biology), family Phocidae, which are commonly refer ...
(''Halichoerus grypus'') and the Baltic
ringed seal The ringed seal (''Pusa hispida'') is an earless seal inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 m in length, with a distinctive patterning of dark spots surrounded by light g ...
(''Pusa hispida botnica''), both of which feed underneath the ice and breed on its surface. Of these two seals, only the Baltic ringed seal suffers when there is not adequate ice in the Baltic Sea, as it feeds its young only while on ice. The grey seal is adapted to reproducing also with no ice in the sea. The sea ice also harbors several species of algae that live in the bottom and inside unfrozen brine pockets in the ice. Due to the often fluctuating winter temperatures between above and below freezing, the saltwater ice of the Baltic Sea can be treacherous and hazardous to walk on, in particular in comparison to the more stable fresh water-ice sheets in the interior lakes.


Hydrography

The Baltic Sea flows out through the
Danish straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
; however, the flow is complex. A surface layer of brackish water discharges per year into the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
. Due to the difference in
salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
, by salinity permeation principle, a sub-surface layer of more saline water moving in the opposite direction brings in per year. It mixes very slowly with the upper waters, resulting in a salinity gradient from top to bottom, with most of the saltwater remaining below deep. The general circulation is anti-clockwise: northwards along its eastern boundary, and south along with the western one .Alhonen, p. 88 The difference between the outflow and the inflow comes entirely from fresh
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
. More than 250 streams drain a basin of about , contributing a volume of per year to the Baltic. They include the major rivers of north Europe, such as the
Oder The Oder ( , ; Czech language, Czech, Lower Sorbian language, Lower Sorbian and ; ) is a river in Central Europe. It is Poland's second-longest river in total length and third-longest within its borders after the Vistula and Warta. The Oder ri ...
, the
Vistula The Vistula (; pl, Wisła, ) is the longest river in Poland and the ninth-longest river in Europe, at in length. The drainage basin, reaching into three other nations, covers , of which is in Poland. The Vistula rises at Barania Góra in t ...
, the
Neman The Neman, Nioman, Nemunas or MemelTo bankside nations of the present: Lithuanian: be, Нёман, , ; russian: Неман, ''Neman''; past: ger, Memel (where touching Prussia only, otherwise Nieman); lv, Nemuna; et, Neemen; pl, Niemen; ...
, the Daugava and the
Neva The Neva (russian: Нева́, ) is a river in northwestern Russia flowing from Lake Ladoga through the western part of Leningrad Oblast (historical region of Ingria) to the Neva Bay of the Gulf of Finland. Despite its modest length of , it is ...
. Additional fresh water comes from the difference of
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, Rain and snow mixed, sleet, snow, ice pellets, ...
less evaporation, which is positive. An important source of salty water is infrequent inflows of
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
water into the Baltic. Such inflows, important to the Baltic ecosystem because of the oxygen they transport into the Baltic deeps, used to happen regularly until the 1980s. In recent decades they have become less frequent. The latest four occurred in 1983, 1993, 2003, and 2014 suggesting a new inter-inflow period of about ten years. The water level is generally far more dependent on the regional wind situation than on tidal effects. However, tidal currents occur in narrow passages in the western parts of the Baltic Sea. Tides can reach 17 to 19 cm in the Gulf of Finland. The
significant wave height In physical oceanography, the significant wave height (SWH, HTSGW or ''H''s) is defined traditionally as the mean ''wave height'' (trough (physics), trough to crest (physics), crest) of the highest third of the ocean surface wave, waves (''H''1/ ...
is generally much lower than that of the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
. Quite violent, sudden storms sweep the surface ten or more times a year, due to large transient temperature differences and a long reach of the wind. Seasonal winds also cause small changes in sea level, of the order of . According to the media, during a storm in January 2017, an extreme wave above 14m has been measured and significant wave height of around 8m has been measured by the FMI. A numerical study has shown the presence of events with 8 to 10m significant wave heights. Those extreme waves events can play an important role in the coastal zone on erosion and sea dynamics.


Salinity

The Baltic Sea is the world's largest inland
brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...
sea. Only two other brackish waters are larger according to some measurements: The
Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of An ...
is larger in both surface area and water volume, but most of it is located outside the
continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
(only a small fraction is inland). The
Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the List of lakes by area, world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad s ...
is larger in water volume, but—despite its name—it is a lake rather than a sea. The Baltic Sea's
salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
is much lower than that of ocean water (which averages 3.5%), as a result of abundant freshwater runoff from the surrounding land (rivers, streams and alike), combined with the shallowness of the sea itself; runoff contributes roughly one-fortieth its total volume per year, as the volume of the basin is about and yearly runoff is about . The open surface waters of the Baltic Sea "proper" generally have a salinity of 0.3 to 0.9%, which is border-line
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which ...
. The flow of freshwater into the sea from approximately two hundred rivers and the introduction of salt from the southwest builds up a gradient of salinity in the Baltic Sea. The highest surface salinities, generally 0.7–0.9%, are in the southwesternmost part of the Baltic, in the Arkona and Bornholm basins (the former located roughly between southeast
Zealand Zealand ( da, Sjælland ) at 7,031 km2 is the largest and most populous islands of Denmark, island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size). Zealand had a population of 2,319,705 on 1 January ...
and Bornholm, and the latter directly east of Bornholm). It gradually falls further east and north, reaching the lowest in the
Bothnian Bay The Bothnian Bay or Bay of Bothnia (; ) is the northernmost part of the Gulf of Bothnia, which is in turn the northern part of the Baltic Sea. The land holding the bay is Post-glacial rebound, still rising after the weight of ice-age glaciers has ...
at around 0.3%. Drinking the surface water of the Baltic as a means of survival would actually hydrate the body instead of dehydrating, as is the case with ocean water.A healthy serum concentration of sodium is around 0.8–0.85%, and healthy kidneys can concentrate salt in urine to at least 1.4%. As saltwater is denser than freshwater, the bottom of the Baltic Sea is saltier than the surface. This creates a vertical stratification of the water column, a halocline, that represents a barrier to the exchange of
oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, a highly Chemical reaction, reactive nonmetal, and an oxidizing a ...
and nutrients, and fosters completely separate maritime environments. The difference between the bottom and surface salinities varies depending on location. Overall it follows the same southwest to east and north pattern as the surface. At the bottom of the Arkona Basin (equalling depths greater than ) and Bornholm Basin (depths greater than ) it is typically 1.4–1.8%. Further east and north the salinity at the bottom is consistently lower, being the lowest in Bothnian Bay (depths greater than ) where it is slightly below 0.4%, or only marginally higher than the surface in the same region. In contrast, the salinity of the
Danish straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
, which connect the Baltic Sea and Kattegat, tends to be significantly higher, but with major variations from year to year. For example, the surface and bottom salinity in the
Great Belt The Great Belt ( da, Storebælt, ) is a strait between the major islands of Zealand (''Sjælland'') and Funen (''Fyn'') in Denmark. It is one of the three Danish straits, Danish Straits. Effectively dividing Denmark in two, the Belt was served ...
is typically around 2.0% and 2.8% respectively, which is only somewhat below that of the Kattegat. The water surplus caused by the continuous inflow of rivers and streams to the Baltic Sea means that there generally is a flow of brackish water out through the Danish Straits to the Kattegat (and eventually the Atlantic). Significant flows in the opposite direction, salt water from the Kattegat through the Danish Straits to the Baltic Sea, are less regular. From 1880 to 1980 inflows occurred on average six to seven times per decade. Since 1980 it has been much less frequent, although a very large inflow occurred in 2014.


Major tributaries

The rating of mean discharges differs from the ranking of hydrological lengths (from the most distant source to the sea) and the rating of the nominal lengths. Göta älv, a tributary of the
Kattegat The Kattegat (; sv, Kattegatt ) is a sea area bounded by the Jutlandic peninsula in the west, the Danish Straits islands of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , ...
, is not listed, as due to the northward upper low-salinity-flow in the sea, its water hardly reaches the Baltic proper:


Islands and archipelagoes

*
Åland Åland ( fi, Ahvenanmaa: ; ; ) is an Federacy, autonomous and Demilitarized zone, demilitarised region of Finland since 1920 by a decision of the League of Nations. It is the smallest region of Finland by area and population, with a size of 1 ...
(
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
,
autonomous In developmental psychology and morality, moral, political, and bioethics, bioethical philosophy, autonomy, from , ''autonomos'', from αὐτο- ''auto-'' "self" and νόμος ''nomos'', "law", hence when combined understood to mean "one who g ...
) *
Archipelago Sea The Archipelago Sea ( fi, Saaristomeri, sv, Skärgårdshavet) is a part of the Baltic Sea between the Gulf of Bothnia, the Gulf of Finland and the Sea of Åland, within Finnish territorial waters. By some definitions it contains the largest ...
(
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
) ** Pargas ** Nagu ** Korpo ** Houtskär **
Kustavi Kustavi (; sv, Gustavs) is a municipality A municipality is usually a single administrative division Administrative division, administrative unit,Article 3(1). country subdivision, administrative region, subnational entity, constituent ...
**
Kimito Kimito (; fi, Kemiö ) is a List of former municipalities of Finland, former municipality of Finland. On January 1, 2009, it was consolidated with Dragsfjärd and Västanfjärd to form the new municipality of Kimitoön. Prior to the consolidation ...
* Blekinge archipelago (
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
) *
Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , ...
, including Christiansø (
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
) *
Falster Falster () is an island in south-eastern Denmark with an area of and 43,398 inhabitants as of 1 January 2010.
(
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
) *
Gotland Gotland (, ; ''Gutland'' in Gutnish), also historically spelled Gottland or Gothland (), is Sweden's largest island. It is also a Provinces of Sweden, province, Counties of Sweden, county, Municipalities of Sweden, municipality, and List of dio ...
(
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
) *
Hailuoto Hailuoto (; sv, Karlö) is a Finnish List of islands in the Baltic Sea, island in the northern Baltic Sea and a municipalities of Finland, municipality in Northern Ostrobothnia Regions of Finland, region. The population of Hailuoto is (), which ...
(
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
) * Kotlin (
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
) *
Lolland Lolland (; formerly spelled ''Laaland'', literally "low land") is the fourth largest island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands su ...
(
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
) *
Kvarken Kvarken ( sv, Kvarken, Norra Kvarken (as opposed to South Kvarken); ) is the narrow region of the Gulf of Bothnia separating the Bothnian Bay (the inner part of the gulf) from the Bothnian Sea. The distance from the Sweden, Swedish mainland to th ...
archipelago, including Valsörarna (
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia Russia (, , ), or the Ru ...
) * Møn (
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
) *
Öland Öland (, ; ; sometimes written ''Øland'' in other Scandinavian languages, and often ''Oland'' internationally; la, Oelandia) is the second-largest Swedish island and the smallest of the traditional provinces of Sweden The provinces ...
(
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
) *
Rügen Rügen (; la, Rugia, ) is Germany's largest List of German islands, island. It is located off the Pomeranian coast in the Baltic Sea and belongs to the state of Mecklenburg-Western Pomerania. The "gateway" to Rügen island is the Hanseatic c ...
(
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between ...
) * Stockholm archipelago (
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
) ** Värmdön (
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
) *
Usedom Usedom (german: Usedom , pl, Uznam ) is a Baltic Sea island in Pomerania, divided between Germany and Poland. It is the second largest Pomeranian island after Rügen, and the most populous island in the Baltic Sea. It is north of the Szczecin ...
or Uznam (split between
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between ...
and
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called Voivodeships of Poland, voivodeships, covering an area of . Poland has a population of over 38 million and is ...
) * West Estonian archipelago (
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe, Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea, sea across from Sweden, to ...
): **
Hiiumaa Hiiumaa (, ) is the second largest island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called ...
** Muhu **
Saaremaa Saaremaa is the largest island in Estonia, measuring . The main island of Saare County, it is located in the Baltic Sea, south of Hiiumaa island and west of Muhu island, and belongs to the West Estonian Archipelago. The capital of the island i ...
** Vormsi *
Wolin Wolin (; formerly german: Wollin ) is the name both of a Poland, Polish island in the Baltic Sea, just off the Polish coast, and a Wolin, Poland, town on that island. Administratively, the island belongs to the West Pomeranian Voivodeship. Woli ...
(
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called Voivodeships of Poland, voivodeships, covering an area of . Poland has a population of over 38 million and is ...
) *
Zealand Zealand ( da, Sjælland ) at 7,031 km2 is the largest and most populous islands of Denmark, island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size). Zealand had a population of 2,319,705 on 1 January ...
(
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
)


Coastal countries

Countries that border the sea: Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden. Countries lands in the outer
drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter ...
: Belarus, Czech Republic, Norway, Slovakia, Ukraine. The Baltic Sea drainage basin is roughly four times the surface area of the sea itself. About 48% of the region is forested, with Sweden and Finland containing the majority of the forest, especially around the Gulfs of Bothnia and Finland. About 20% of the land is used for agriculture and pasture, mainly in Poland and around the edge of the Baltic Proper, in Germany, Denmark, and Sweden. About 17% of the basin is unused open land with another 8% of wetlands. Most of the latter are in the Gulfs of Bothnia and Finland. The rest of the land is heavily populated. About 85 million people live in the Baltic drainage basin, 15 million within of the coast and 29 million within of the coast. Around 22 million live in population centers of over 250,000. 90% of these are concentrated in the band around the coast. Of the nations containing all or part of the basin, Poland includes 45% of the 85 million, Russia 12%, Sweden 10% and the others less than 6% each.


Cities

The biggest coastal cities (by population): *
Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...
(Russia) 5,392,992 (metropolitan area 6,000,000) *
Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...
(Sweden) 962,154 (metropolitan area 2,315,612) *
Helsinki Helsinki ( or ; ; sv, Helsingfors, ) is the Capital city, capital, primate city, primate, and List of cities and towns in Finland, most populous city of Finland. Located on the shore of the Gulf of Finland, it is the seat of the region of U ...
(Finland) 658,864 (metropolitan area 1,536,810) *
Riga Riga (; lv, Rīga , liv, Rīgõ) is the capital and largest city of Latvia and is home to 605,802 inhabitants which is a third of Latvia's population. The city lies on the Gulf of Riga at the mouth of the Daugava (river), Daugava river where ...
(Latvia) 614,618 (metropolitan area 1,070,00) *
Gdańsk Gdańsk ( , also ; ; csb, Gduńsk;Stefan Ramułt, ''Słownik języka pomorskiego, czyli kaszubskiego'', Kraków 1893, Gdańsk 2003, ISBN 83-87408-64-6. , Johann Georg Theodor Grässe, ''Orbis latinus oder Verzeichniss der lateinischen Benen ...
(Poland) 462,700 (
metropolitan area A metropolitan area or metro is a region that consists of a densely populated urban area, urban agglomeration and its surrounding territories sharing Industry (economics), industries, commercial areas, Transport infrastructure, transport net ...
1,041,000) *
Tallinn Tallinn () is the most populous and capital city of Estonia. Situated on a Tallinn Bay, bay in north Estonia, on the shore of the Gulf of Finland of the Baltic Sea, Tallinn has a population of 437,811 (as of 2022) and administratively lies in t ...
(Estonia) 435,245 (metropolitan area 542,983) *
Kaliningrad Kaliningrad ( ; rus, Калининград, p=kəlʲɪnʲɪnˈɡrat, links=y), until 1946 known as Königsberg (; rus, Кёнигсберг, Kyonigsberg, ˈkʲɵnʲɪɡzbɛrk; rus, Короле́вец, Korolevets), is the largest city and ...
(Russia) 431,500 *
Szczecin Szczecin (, , german: Stettin ; sv, Stettin ; Latin language, Latin: ''Sedinum'' or ''Stetinum'') is the capital city, capital and largest city of the West Pomeranian Voivodeship in northwestern Poland. Located near the Baltic Sea and the Po ...
(Poland) 413,600 (metropolitan area 778,000) *
Gdynia Gdynia ( ; ; german: Gdingen (currently), (1939–1945); csb, Gdiniô, , , ) is a city in northern Poland and a seaport on the Baltic Sea coast. With a population of 243,918, it is the List of cities in Poland, 12th-largest city in Poland and ...
(Poland) 255,600 (
metropolitan area A metropolitan area or metro is a region that consists of a densely populated urban area, urban agglomeration and its surrounding territories sharing Industry (economics), industries, commercial areas, Transport infrastructure, transport net ...
1,041,000) *
Espoo Espoo (, ; sv, Esbo) is a List of cities and towns in Finland, city and Municipalities of Finland, municipality in the region of Uusimaa in the Finland, Republic of Finland. It is located on the northern shore of the Gulf of Finland, bordering ...
(Finland) 257,195 (part of Helsinki metropolitan area) *
Kiel Kiel () is the capital and most populous city in the northern Germany, German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the J ...
(Germany) 247,000 *
Lübeck Lübeck (; Low German also ), officially the Hanseatic City of Lübeck (german: Hansestadt Lübeck), is a city in Northern Germany. With around 217,000 inhabitants, Lübeck is the second-largest city on the German Baltic Sea, Baltic coast and ...
(Germany) 216,100 *
Rostock Rostock (), officially the Hanseatic and University City of Rostock (german: link=no, Hanse- und Universitätsstadt Rostock), is the largest city in the German States of Germany, state of Mecklenburg-Vorpommern and lies in the Mecklenburgian p ...
(Germany) 212,700 * Klaipėda (Lithuania) 194,400 *
Oulu Oulu ( , ; sv, Uleåborg ) is a List of cities and towns in Finland, city, Municipalities of Finland, municipality and a seaside resort of about 210,000 inhabitants in the region of North Ostrobothnia, Finland. It is the most populous city in no ...
(Finland) 191,050 *
Turku Turku ( ; ; sv, Åbo, ) is a List of cities and towns in Finland, city and former Capital city, capital on the southwest coast of Finland at the mouth of the Aura (Archipelago Sea), Aura River, in the region of Southwest Finland, Finland Proper ...
(Finland) 180,350 Other important ports: * ''Estonia:'' **
Pärnu Pärnu () is the fourth largest city in Estonia. Situated in southwest Estonia, Pärnu is located south of the Estonian capital, Tallinn, and west of Estonia's second largest city, Tartu. The city sits off the coast of Pärnu Bay, an inlet of ...
44,568 **
Maardu Maardu (german: Maart) is a town A town is a human settlement In geography, statistics and archaeology, a settlement, locality or populated place is a community in which people live. The complexity of a settlement can range fr ...
16,570 ** Sillamäe 16,567 * ''Finland:'' **
Pori ) , website www.pori.fi Pori (; sv, Björneborg ) is a city A city is a human settlement of notable size.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Scie ...
83,272 **
Kotka Kotka (; ; la, Aquilopolis) is a city in the southern part of the Kymenlaakso Kymenlaakso ( sv, Kymmenedalen; "Kymi River, Kymi/Kymmene Valley") is a Regions of Finland, region in Finland. It borders the regions of Uusimaa, Päijät-Häme, S ...
54,887 **
Kokkola Kokkola (; sv, Karleby, ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. The town is located in the Central Ostrobothnia regions of Finland, region. The town has a population of () and covers an area of of ...
46,809 ** Port of Naantali 18,789 **
Mariehamn Mariehamn ( , ; fi, Maarianhamina ; la, Portus Mariae) is the capital Capital may refer to: Common uses * Capital city, a municipality of primary status ** List of national capitals, List of national capital cities * Capital letter, an upp ...
11,372 ** Hanko 9,270 * ''Germany:'' **
Flensburg Flensburg (; Danish language, Danish, Northern Low Saxon, Low Saxon: ''Flensborg''; North Frisian language, North Frisian: ''Flansborj''; South Jutlandic: ''Flensborre'') is an independent city, independent town (''kreisfreie Stadt'') in the nor ...
94,000 **
Stralsund Stralsund (; Swedish language, Swedish: ''Strålsund''), officially the Hanseatic City of Stralsund (German language, German: ''Hansestadt Stralsund''), is the fifth-largest city in the northeastern German federal state of Mecklenburg-Western Pome ...
58,000 **
Greifswald Greifswald (), officially the University and Hanseatic City of Greifswald (german: Universitäts- und Hansestadt Greifswald, Low German: ''Griepswoold'') is the fourth-largest city in the German state of Mecklenburg-Western Pomerania after Rostoc ...
55,000 **
Wismar Wismar (; Low German: ''Wismer''), officially the Hanseatic City of Wismar (''Hansestadt Wismar'') is, with around 43,000 inhabitants, the sixth-largest city of the northeastern German state of Mecklenburg-Vorpommern, and the fourth-largest city ...
44,000 ** Eckernförde 22,000 ** Neustadt in Holstein 16,000 **
Wolgast Wolgast (; csb, Wòłogòszcz) is a town in the district of Vorpommern-Greifswald, in Mecklenburg-Vorpommern, Germany. It is situated on the bank of the river (or strait) Peenestrom, vis-a-vis the island of Usedom on the Baltic Sea, Baltic coast ...
12,000 **
Sassnitz Sassnitz (, before 1993 in german: Saßnitz) is a town on the Jasmund peninsula, Rügen Island, in the States of Germany, state of Mecklenburg-Vorpommern, Germany. The population as of 2012 was 9,498. Sassnitz is a well-known seaside resort and ...
10,000 * ''Latvia:'' ** Liepāja 85,000 **
Ventspils Ventspils (; german: Windau, ; see #Other names, other names) is a state city in northwestern Latvia in the historical Courland region of Latvia, and is the sixth largest city in the country. At the beginning of 2020, Ventspils had a population ...
44,000 * ''Lithuania:'' **
Palanga Palanga (; bat-smg, Palonga; pl, Połąga; german: Polangen) is a seaside resort town in western Lithuania, on the shore of the Baltic Sea. Palanga is the busiest summer resort in Lithuania and has sandy beaches (18 km, 11 miles lo ...
17,000 * ''Poland:'' ** Kołobrzeg 44,800 ** Świnoujście 41,500 **
Police The police are a Law enforcement organization, constituted body of Law enforcement officer, persons empowered by a State (polity), state, with the aim to law enforcement, enforce the law, to ensure the safety, health and possessions of citize ...
34,284 ** Władysławowo 15,000 ** Darłowo 14,000 * ''Russia:'' **
Vyborg Vyborg (; rus, Вы́борг, links=1, r=Výborg, p=ˈvɨbərk; fi, Viipuri ; sv, Viborg ; german: Wiborg ) is a Classification of inhabited localities in Russia, town in, and the administrative center of, Vyborgsky District, Leningrad Obl ...
79,962 ** Baltiysk 34,000 * ''Sweden:'' **
Norrköping Norrköping (; ) is a city A city is a human settlement of notable size.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Science Encyclopedia''. 2nd edition. Lo ...
84,000 **
Gävle Gävle () is a Urban areas in Sweden, city in Sweden, the seat of Gävle Municipality and the capital of Gävleborg County. It had 77,586 inhabitants in 2020, which makes it the List of cities in Sweden, 13th most populated city in Sweden. It is t ...
75,451 **
Trelleborg Trelleborg () is a town in Skåne County, Sweden, with 43,359 inhabitants as of December 31, 2015. It is the southernmost town in Sweden located some west from the southernmost point of Sweden and the Scandinavian peninsula. It is one of the mo ...
26,000 ** Karlshamn 19,000 ** Oxelösund 11,000


Geology

The Baltic Sea somewhat resembles a
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
bed, with two tributaries, the
Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
and
Gulf of Bothnia The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost Arm (geography), arm of the Baltic Sea, between Finland's west coast (Ostrobothnia (historical provinc ...
.
Geological Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
surveys show that before the
Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...
, instead of the Baltic Sea, there was a wide plain around a great river that paleontologists call the Eridanos. Several Pleistocene
glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...
episodes scooped out the river bed into the sea basin. By the time of the last, or
Eemian Stage The Eemian (also called the last interglacial, Sangamonian, Sangamonian Stage, Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Ri ...
( MIS 5e), the Eemian Sea was in place. Instead of a true sea, the Baltic can even today also be understood as the common
estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...
of all rivers flowing into it. From that time the waters underwent a geologic history summarized under the names listed below. Many of the stages are named after marine animals (e.g. the Littorina
mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil sp ...
) that are clear markers of changing water temperatures and salinity. The factors that determined the sea's characteristics were the submergence or emergence of the region due to the weight of ice and subsequent isostatic readjustment, and the connecting channels it found to the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
-
Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
, either through the straits of
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
or at what are now the large lakes of
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
, and the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian language, Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast o ...
-
Arctic Sea The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...
. * Eemian Sea, 130,000–115,000 ( years ago) * Baltic Ice Lake, 12,600–10,300 * Yoldia Sea, 10,300–9500 *
Ancylus Lake Ancylus Lake is a name given by geologists to a large freshwater lake that existed in northern Europe approximately from 9500 to 8000 years B.C being in effect one of various predecessors to the modern Baltic Sea. Origin, evolution and demise The ...
, 9,500–8,000 * Mastogloia Sea, 8,000–7,500 * Littorina Sea, 7,500–4,000 * Post-Littorina Sea, 4,000–present The land is still emerging isostatically from its depressed state, which was caused by the weight of ice during the last glaciation. The phenomenon is known as
post-glacial rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound an ...
. Consequently, the surface area and the depth of the sea are diminishing. The uplift is about eight millimeters per year on the Finnish coast of the northernmost Gulf of Bothnia. In the area, the former seabed is only gently sloping, leading to large areas of land being reclaimed in what are, geologically speaking, relatively short periods (decades and centuries).


The "Baltic Sea anomaly"

The "Baltic Sea anomaly" is a feature on an indistinct
sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect o ...
image taken by Swedish salvage divers on the floor of the northern Baltic Sea in June 2011. The treasure hunters suggested the image showed an object with unusual features of seemingly extraordinary origin. Speculation published in tabloid newspapers claimed that the object was a sunken
UFO An unidentified flying object (UFO), more recently renamed by US officials as a UAP (unidentified aerial phenomenon), is any perceived aerial phenomenon that cannot be immediately identified or explained. On investigation, most UFOs are Ide ...
. A consensus of experts and scientists say that the image most likely shows a natural
geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...
.Interview of Finnish planetary geomorphologist Jarmo Korteniemi (at 1:10:45) on


Biology


Fauna and flora

The fauna of the Baltic Sea is a mixture of marine and freshwater species. Among marine fishes are
Atlantic cod The Atlantic cod (''Gadus morhua'') is a benthopelagic fish of the family Gadidae, widely seafood, consumed by humans. It is also Commercial fishing, commercially known as cod or codling.Atlantic herring Atlantic herring (''Clupea harengus'') is a herring in the family (biology), family Clupeidae. It is one of the most abundant fish species in the world. Atlantic herrings can be found on both sides of the Atlantic Ocean, congregating in large ...
, European hake, European plaice, European flounder,
shorthorn sculpin ''Myoxocephalus scorpius'', typically known as the shorthorn sculpin or bull-rout, is a species of fish in the family Cottidae. It is a demersal species of the Northern Atlantic and adjacent subarctic and Arctic Ocean, Arctic seas.
and
turbot The turbot (''Scophthalmus maximus'') is a relatively large species of flatfish in the family (biology), family Scophthalmidae. It is a demersal fish native to marine (ocean), marine or brackish waters of the Northeast Atlantic, Baltic Sea and t ...
, and examples of freshwater species include European perch,
northern pike The northern pike (''Esox lucius'') is a species of carnivorous fish of the genus ''Esox'' (the pikes). They are typical of brackish water, brackish and fresh waters of the Northern Hemisphere (''i.e.'' holarctic in distribution). They are kno ...
, whitefish and common roach. Freshwater species may occur at outflows of rivers or streams in all coastal sections of the Baltic Sea. Otherwise, marine species dominate in most sections of the Baltic, at least as far north as
Gävle Gävle () is a Urban areas in Sweden, city in Sweden, the seat of Gävle Municipality and the capital of Gävleborg County. It had 77,586 inhabitants in 2020, which makes it the List of cities in Sweden, 13th most populated city in Sweden. It is t ...
, where less than one-tenth are freshwater species. Further north the pattern is inverted. In the Bothnian Bay, roughly two-thirds of the species are freshwater. In the far north of this bay, saltwater species are almost entirely absent. For example, the common starfish and shore crab, two species that are very widespread along European coasts, are both unable to cope with the significantly lower salinity. Their range limit is west of Bornholm, meaning that they are absent from the vast majority of the Baltic Sea. Some marine species, like the Atlantic cod and European flounder, can survive at relatively low salinities but need higher salinities to breed, which therefore occurs in deeper parts of the Baltic Sea. There is a decrease in species richness from the Danish belts to the
Gulf of Bothnia The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost Arm (geography), arm of the Baltic Sea, between Finland's west coast (Ostrobothnia (historical provinc ...
. The decreasing salinity along this path causes restrictions in both physiology and habitats. At more than 600 species of invertebrates, fish, aquatic mammals, aquatic birds and macrophytes, the Arkona Basin (roughly between southeast Zealand and Bornholm) is far richer than other more eastern and northern basins in the Baltic Sea, which all have less than 400 species from these groups, with the exception of the Gulf of Finland with more than 750 species. However, even the most diverse sections of the Baltic Sea have far fewer species than the almost-full saltwater Kattegat, which is home to more than 1600 species from these groups. The lack of
tide Tides are the rise and fall of sea levels caused by the combined effects of the gravity, gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide t ...
s has affected the marine species as compared with the Atlantic. Since the Baltic Sea is so young there are only two or three known
endemic Endemism is the state of a species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of or ...
species: the brown alga ''
Fucus radicans ''Fucus radicans'' is a species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organis ...
'' and the flounder '' Platichthys solemdali''. Both appear to have evolved in the Baltic basin and were only recognized as species in 2005 and 2018 respectively, having formerly been confused with more widespread relatives. The tiny Copenhagen cockle (''Parvicardium hauniense''), a rare mussel, is sometimes considered endemic, but has now been recorded in the Mediterranean. However, some consider non-Baltic records to be misidentifications of juvenile lagoon cockles (''Cerastoderma glaucum''). Several widespread marine species have distinctive subpopulations in the Baltic Sea adapted to the low salinity, such as the Baltic Sea forms of the Atlantic herring and lumpsucker, which are smaller than the widespread forms in the North Atlantic. A peculiar feature of the fauna is that it contains a number of glacial relict species, isolated populations of arctic species which have remained in the Baltic Sea since the last
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...
, such as the large isopod '' Saduria entomon'', the Baltic subspecies of
ringed seal The ringed seal (''Pusa hispida'') is an earless seal inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 m in length, with a distinctive patterning of dark spots surrounded by light g ...
, and the
fourhorn sculpin The fourhorn sculpin (''Myoxocephalus quadricornis'') is a species of fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the l ...
. Some of these relicts are derived from
glacial lake A glacial lake is a body of water with origins from glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ab ...
s, such as '' Monoporeia affinis'', which is a main element in the
benthic fauna Benthos (), also known as benthon, is the community (ecology), community of organisms that live on, in, or near the bottom of a seabed, sea, river, lake, or stream, also known as the benthic zone.
of the low-salinity
Bothnian Bay The Bothnian Bay or Bay of Bothnia (; ) is the northernmost part of the Gulf of Bothnia, which is in turn the northern part of the Baltic Sea. The land holding the bay is Post-glacial rebound, still rising after the weight of ice-age glaciers has ...
.
Cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel th ...
s in the Baltic Sea are monitored by the countries bordering the sea and data compiled by various intergovernmental bodies, such as
ASCOBANS Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas, often abbreviated to ASCOBANS, is a regional agreement on the protection of small cetaceans that was concluded as the Agreement on the Con ...
. A critically endangered population of
harbor porpoise The harbour porpoise (''Phocoena phocoena'') is one of eight extant species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is ...
inhabit the Baltic proper, whereas the species is abundant in the outer Baltiuc (Western Baltic and
Danish Straits The Danish straits are the straits A strait is an Ocean, oceanic landform connecting two Sea, seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either di ...
) and occasionally oceanic and out-of-range species such as minke whales,
bottlenose dolphin Bottlenose dolphins are Aquatic mammal, aquatic mammals in the genus ''Tursiops.'' They are common, cosmopolitan distribution, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. molecular biology, Molecular studies ...
s,
beluga whale The beluga whale () (''Delphinapterus leucas'') is an Arctic and sub-Arctic cetacean. It is one of two members of the family Monodontidae, along with the narwhal, and the only member of the genus ''Delphinapterus''. It is also known as the whi ...
s,
orca The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only Extant taxon, extant species in the genus ''Orcinus'' and is recognizable by its black ...
s, and
beaked whale Beaked whales (systematic name Ziphiidae) are a Family (biology), family of cetaceans noted as being one of the least known groups of mammals because of their deep-sea habitat and apparent low abundance. Only three or four of the 24 species are ...
s visit the waters. In recent years, very small, but with increasing rates,
fin whale The fin whale (''Balaenoptera physalus''), also known as finback whale or common rorqual and formerly known as herring whale or razorback whale, is a cetacean belonging to the Order (biology)#Zoology, parvorder of baleen whales. It is the secon ...
s and
humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the monotypic taxon, only species in the genus ''Megaptera''. Adults range in length from and weigh u ...
s migrate into Baltic sea including mother and calf pair. Now extinct Atlantic
grey whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bree ...
s (remains found from Gräsö along Bothnian Sea/southern Bothnian Gulf and
Ystad Ystad (; older da, Ysted) is a Urban areas in Sweden, town and the seat of Ystad Municipality, in Scania County, Sweden. Ystad had 18,350 inhabitants in 2010. The settlement dates from the 11th century and has become a busy ferryport, local adm ...
) and eastern population of
North Atlantic right whale The North Atlantic right whale (''Eubalaena glacialis'') is a baleen whale, one of three right whale species belonging to the genus ''Eubalaena'', all of which were formerly classified as a single species. Because of their docile nature, their sl ...
s that is facing
functional extinction Functional extinction is the extinction of a species or other taxon such that: #It disappears from the fossil record, or historic reports of its existence cease; #The reduced population no longer plays a significant role in ecosystem function; or ...
once migrated into Baltic Sea. Other notable
megafauna In terrestrial zoology, the megafauna (from Ancient Greek, Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most c ...
include the
basking shark The basking shark (''Cetorhinus maximus'') is the second-largest living shark and fish, after the whale shark, and one of three Planktivore, plankton-eating shark species, along with the whale shark and megamouth shark. Adults typically reach ...
s.


Environmental status

Satellite images taken in July 2010 revealed a massive
algal bloom An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in Fresh water, freshwater or Ocean, marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ...
covering in the Baltic Sea. The area of the bloom extended from Germany and Poland to Finland. Researchers of the phenomenon have indicated that algal blooms have occurred every summer for decades. Fertilizer runoff from surrounding agricultural land has exacerbated the problem and led to increased
eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly Nitrogen cycle, nitrogen and Phosphorus cycle, phosphorus. It has also been defined as "nutri ...
. Approximately of the Baltic's seafloor (a quarter of its total area) is a variable dead zone. The more saline (and therefore denser) water remains on the bottom, isolating it from surface waters and the atmosphere. This leads to decreased oxygen concentrations within the zone. It is mainly bacteria that grow in it, digesting organic material and releasing hydrogen sulfide. Because of this large anaerobic zone, the seafloor ecology differs from that of the neighboring Atlantic. Plans to artificially oxygenate areas of the Baltic that have experienced eutrophication have been proposed by the
University of Gothenburg The University of Gothenburg ( sv, Göteborgs universitet) is a university A university () is an educational institution, institution of higher education, higher (or Tertiary education, tertiary) education and research which awards academic ...
and Inocean AB. The proposal intends to use wind-driven pumps to inject oxygen (air) into waters at, or around, 130m below sea level. After
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, Germany had to be disarmed and large quantities of ammunition stockpiles were disposed directly into the Baltic Sea and the North Sea. Environmental experts and marine biologists warn that these ammunition dumps pose a major environmental threat with potentially life-threatening consequences to the health and safety of humans on the coastlines of these seas.


Economy

Construction of the Great Belt Bridge in Denmark (completed 1997) and the Øresund Bridge-Tunnel (completed 1999), linking Denmark with Sweden, provided a highway and railroad connection between Sweden and the Danish mainland (the
Jutland Peninsula Jutland ( da, Jylland ; german: Jütland ; ang, Ēota land ), known anciently as the Cimbric or Cimbrian Peninsula ( la, Cimbricus Chersonesus; da, den Kimbriske Halvø, links=no or ; german: Kimbrische Halbinsel, links=no), is a peninsula of ...
, precisely the
Zealand Zealand ( da, Sjælland ) at 7,031 km2 is the largest and most populous islands of Denmark, island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size). Zealand had a population of 2,319,705 on 1 January ...
). The undersea tunnel of the Øresund Bridge-Tunnel provides for navigation of large ships into and out of the Baltic Sea. The Baltic Sea is the main trade route for the export of Russian petroleum. Many of the countries neighboring the Baltic Sea have been concerned about this since a major oil leak in a seagoing tanker would be disastrous for the Baltic—given the slow exchange of water. The tourism industry surrounding the Baltic Sea is naturally concerned about
oil pollution An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...
. Much shipbuilding is carried out in the shipyards around the Baltic Sea. The largest shipyards are at
Gdańsk Gdańsk ( , also ; ; csb, Gduńsk;Stefan Ramułt, ''Słownik języka pomorskiego, czyli kaszubskiego'', Kraków 1893, Gdańsk 2003, ISBN 83-87408-64-6. , Johann Georg Theodor Grässe, ''Orbis latinus oder Verzeichniss der lateinischen Benen ...
,
Gdynia Gdynia ( ; ; german: Gdingen (currently), (1939–1945); csb, Gdiniô, , , ) is a city in northern Poland and a seaport on the Baltic Sea coast. With a population of 243,918, it is the List of cities in Poland, 12th-largest city in Poland and ...
, and
Szczecin Szczecin (, , german: Stettin ; sv, Stettin ; Latin language, Latin: ''Sedinum'' or ''Stetinum'') is the capital city, capital and largest city of the West Pomeranian Voivodeship in northwestern Poland. Located near the Baltic Sea and the Po ...
, Poland;
Kiel Kiel () is the capital and most populous city in the northern Germany, German state of Schleswig-Holstein, with a population of 246,243 (2021). Kiel lies approximately north of Hamburg. Due to its geographic location in the southeast of the J ...
, Germany;
Karlskrona Karlskrona (, , ) is a urban areas of Sweden, locality and the seat of Karlskrona Municipality, Blekinge County, Sweden with a population of 66,675 in 2018. It is also the capital of Blekinge County. Karlskrona is known as Sweden's only baroque c ...
and
Malmö Malmö (, ; da, Malmø ) is the largest city in the Counties of Sweden, Swedish county (län) of Skåne County, Scania (Skåne). It is the List of urban areas in Sweden by population, third-largest city in Sweden, after Stockholm and Gothenbur ...
, Sweden; Rauma,
Turku Turku ( ; ; sv, Åbo, ) is a List of cities and towns in Finland, city and former Capital city, capital on the southwest coast of Finland at the mouth of the Aura (Archipelago Sea), Aura River, in the region of Southwest Finland, Finland Proper ...
, and
Helsinki Helsinki ( or ; ; sv, Helsingfors, ) is the Capital city, capital, primate city, primate, and List of cities and towns in Finland, most populous city of Finland. Located on the shore of the Gulf of Finland, it is the seat of the region of U ...
, Finland;
Riga Riga (; lv, Rīga , liv, Rīgõ) is the capital and largest city of Latvia and is home to 605,802 inhabitants which is a third of Latvia's population. The city lies on the Gulf of Riga at the mouth of the Daugava (river), Daugava river where ...
,
Ventspils Ventspils (; german: Windau, ; see #Other names, other names) is a state city in northwestern Latvia in the historical Courland region of Latvia, and is the sixth largest city in the country. At the beginning of 2020, Ventspils had a population ...
, and Liepāja, Latvia; Klaipėda, Lithuania; and
Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...
, Russia. There are several cargo and passenger ferries that operate on the Baltic Sea, such as
Scandlines Scandlines is a ferry company that operates the Rødby–Puttgarden and Gedser–Rostock ferry routes between Denmark and Germany. Scandlines owns 7 ferries, 6 of which are hybrid ferries, making Scandlines the owner of the world's largest fl ...
, Silja Line, Polferries, the
Viking Line Viking Line Abp is a Finland, Finnish shipping company that operates a fleet of ferry, ferries and cruiseferry, cruiseferries between Finland, the Åland, Åland Islands, Sweden and Estonia. Viking Line shares are quoted on the Helsinki Stock E ...
, Tallink, and Superfast Ferries. Construction of the
Fehmarn Belt Fixed Link The Fehmarn Belt fixed link ( da, Femern Bælt-forbindelsen, german: Fehmarnbelt-Querung) or Fehmarn Belt tunnel is an under-construction immersed tunnel, which will connect the Danish island of Lolland with the German island of Fehmarn, crossi ...
between Denmark and Germany is due to finish in 2029. It will be a three-bore tunnel carrying four motorway lanes and two rail tracks.


Tourism

Piers *
Ahlbeck (Usedom) Ahlbeck is a village (''Ortsteil'') of the Heringsdorf, Mecklenburg-Vorpommern, Heringsdorf municipality on the island of Usedom on the Baltic Sea, Baltic coast. It is the easternmost of the so-called ''Kaiserbäder'' ("Imperial Spas") seaside re ...
, Germany * Bansin, Germany *
Binz Binz is the largest seaside resort A seaside resort is a resort town, town, village, or hotel that serves as a Resort, vacation resort and is located on a coast. Sometimes the concept includes an aspect of official accreditation based on the sati ...
, Germany * Heiligendamm, Germany * Kühlungsborn, Germany * Sellin, Germany * Liepāja, Latvia * Šventoji, Lithuania * Klaipėda, Lithuania *
Gdańsk Gdańsk ( , also ; ; csb, Gduńsk;Stefan Ramułt, ''Słownik języka pomorskiego, czyli kaszubskiego'', Kraków 1893, Gdańsk 2003, ISBN 83-87408-64-6. , Johann Georg Theodor Grässe, ''Orbis latinus oder Verzeichniss der lateinischen Benen ...
, Poland *
Gdynia Gdynia ( ; ; german: Gdingen (currently), (1939–1945); csb, Gdiniô, , , ) is a city in northern Poland and a seaport on the Baltic Sea coast. With a population of 243,918, it is the List of cities in Poland, 12th-largest city in Poland and ...
, Poland * Kołobrzeg, Poland * Misdroy, Poland *
Sopot Sopot is a seaside resort city in Pomerelia on the southern coast of the Baltic Sea in northern Poland, with a population of approximately 40,000. It is located in Pomeranian Voivodeship, and has the City with powiat rights, status of the powiat, ...
, Poland Resort towns *
Haapsalu Haapsalu () is a seaside resort town A resort town, often called a resort city or resort destination, is an urban area where tourism or vacationing is the primary component of the local culture and economy. A typical resort town has one ...
, Estonia *
Kuressaare Kuressaare () is a populated places in Estonia, town on Saaremaa island in Estonia. It is the administrative centre of Saaremaa Parish and the capital of Saare County. Kuressaare is the westernmost town in Estonia. The recorded population on 1 ...
, Estonia * Narva-Jõesuu, Estonia *
Pärnu Pärnu () is the fourth largest city in Estonia. Situated in southwest Estonia, Pärnu is located south of the Estonian capital, Tallinn, and west of Estonia's second largest city, Tartu. The city sits off the coast of Pärnu Bay, an inlet of ...
, Estonia * Hanko, Finland *
Mariehamn Mariehamn ( , ; fi, Maarianhamina ; la, Portus Mariae) is the capital Capital may refer to: Common uses * Capital city, a municipality of primary status ** List of national capitals, List of national capital cities * Capital letter, an upp ...
, Finland *
Binz Binz is the largest seaside resort A seaside resort is a resort town, town, village, or hotel that serves as a Resort, vacation resort and is located on a coast. Sometimes the concept includes an aspect of official accreditation based on the sati ...
, Germany * Heiligendamm, Germany * Heringsdorf, Germany * Travemünde, Germany * Sellin, Germany * Ueckermünde, Germany * Jūrmala, Latvia * Nida, Lithuania *
Palanga Palanga (; bat-smg, Palonga; pl, Połąga; german: Polangen) is a seaside resort town in western Lithuania, on the shore of the Baltic Sea. Palanga is the busiest summer resort in Lithuania and has sandy beaches (18 km, 11 miles lo ...
, Lithuania * Šventoji, Lithuania * Juodkrantė, Lithuania * Pervalka, Lithuania * Karklė, Lithuania * Kamień Pomorski, Poland * Kołobrzeg, Poland *
Sopot Sopot is a seaside resort city in Pomerelia on the southern coast of the Baltic Sea in northern Poland, with a population of approximately 40,000. It is located in Pomeranian Voivodeship, and has the City with powiat rights, status of the powiat, ...
, Poland * Świnoujście, Poland *
Ustka Ustka (pronounced ; csb, Ùskô; german: Stolpmünde) is a spa town in the Middle Pomerania region of northern Poland with 17,100 inhabitants (2001). It is part of Słupsk County in Pomeranian Voivodeship. It is located on the Slovincian Coast on ...
, Poland * Svetlogorsk, Russia


The Helsinki Convention


1974 Convention

For the first time ever, all the sources of pollution around an entire sea were made subject to a single convention, signed in 1974 by the then seven Baltic coastal states. The 1974 Convention entered into force on 3 May 1980.


1992 Convention

In the light of political changes and developments in international environmental and maritime law, a new convention was signed in 1992 by all the states bordering on the Baltic Sea, and the European Community. After ratification, the Convention entered into force on 17 January 2000. The Convention covers the whole of the Baltic Sea area, including inland waters and the water of the sea itself, as well as the seabed. Measures are also taken in the whole catchment area of the Baltic Sea to reduce land-based pollution. The convention on the Protection of the Marine Environment of the Baltic Sea Area, 1992, entered into force on 17 January 2000. The governing body of the convention is the Helsinki Commission,Helcom : Welcome
. Helcom.fi. Retrieved on 23 June 2011.
also known as HELCOM, or Baltic Marine Environment Protection Commission. The present contracting parties are Denmark, Estonia, the European Community, Finland, Germany, Latvia, Lithuania, Poland, Russia, and Sweden. The ratification instruments were deposited by the European Community, Germany, Latvia and Sweden in 1994, by Estonia and Finland in 1995, by Denmark in 1996, by Lithuania in 1997, and by Poland and Russia in November 1999.


See also

* Baltic (disambiguation) *
Baltic region The terms Baltic Sea Region, Baltic Rim countries (or simply the Baltic Rim), and the Baltic Sea countries/states refer to slightly different combinations of countries in the general area surrounding the Baltic Sea, mainly in Northern Europe. T ...
* Baltic Sea Action Group (BSAG) *
Council of the Baltic Sea States The Council of the Baltic Sea States (CBSS) is a regional intergovernmental organisation working on three priority areas: Regional Identity, Safe & Secure Region and Sustainable & Prosperous Region. These three priority areas aim to address ...
*
List of cities and towns around the Baltic Sea List of rivers of the Baltic Sea * Nord Stream 1 * Nord Stream 2 *
Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...
*
Ports of the Baltic Sea There are over 200 ports in the Baltic Sea (or 190, when only those ports that handle a minimum of 50,000 tonnes of cargo annually and where at least part of this cargo is international are taken into account). In 2008, the total amount of cargo ...
*
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion#Europe, subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, ...


Notes


References


Bibliography

* *


Further reading


Norbert Götz. “Spatial Politics and Fuzzy Regionalism: The Case of the Baltic Sea Area.” ''Baltic Worlds'' 9 (2016) 3: 54–67.
* Aarno Voipio (ed., 1981): "The Baltic Sea." Elsevier Oceanography Series, vol. 30, Elsevier Scientific Publishing, 418 p, * * *


Historical

* Bogucka, Maria. "The Role of Baltic Trade in European Development from the XVIth to the XVIIIth Centuries". ''Journal of European Economic History'' 9 (1980): 5–20. * Davey, James. ''The Transformation of British Naval Strategy: Seapower and Supply in Northern Europe, 1808–1812'' (Boydell, 2012). * Fedorowicz, Jan K. ''England's Baltic Trade in the Early Seventeenth Century: A Study in Anglo-Polish Commercial Diplomacy'' (Cambridge UP, 2008). * Frost, Robert I. ''The Northern Wars: War, State, and Society in Northeastern Europe, 1558–1721'' (Longman, 2000). * Grainger, John D. ''The British Navy in the Baltic'' (Boydell, 2014). * Kent, Heinz S. K. ''War and Trade in Northern Seas: Anglo-Scandinavian Economic Relations in the Mid Eighteenth Century'' (Cambridge UP, 1973). * Koningsbrugge, Hans van. "In War and Peace: The Dutch and the Baltic in Early Modern Times". ''Tijdschrift voor Skandinavistiek'' 16 (1995): 189–200. * Lindblad, Jan Thomas. "Structural Change in the Dutch Trade in the Baltic in the Eighteenth Century". ''Scandinavian Economic History Review'' 33 (1985): 193–207. * Lisk, Jill. ''The Struggle for Supremacy in the Baltic, 1600–1725'' (U of London Press, 1967). * Roberts, Michael. ''The Early Vasas: A History of Sweden, 1523–1611'' (Cambridge UP, 1968). * Rystad, Göran, Klaus-R. Böhme, and Wilhelm M. Carlgren, eds. ''In Quest of Trade and Security: The Baltic in Power Politics, 1500–1990.'' Vol. 1, 1500–1890. Stockholm: Probus, 1994. * Salmon, Patrick, and Tony Barrow, eds. ''Britain and the Baltic: Studies in Commercial, Political and Cultural Relations'' (Sunderland University Press, 2003). * Stiles, Andrina. ''Sweden and the Baltic 1523–1721'' (1992). * Thomson, Erik. "Beyond the Military State: Sweden's Great Power Period in Recent Historiography". ''History Compass'' 9 (2011): 269–283. * Tielhof, Milja van. The "Mother of All Trades": The Baltic Grain Trade in Amsterdam from the Late 16th to Early 19th Century. Leiden, The Netherlands: Brill, 2002. * Warner, Richard. "British Merchants and Russian Men-of-War: The Rise of the Russian Baltic Fleet". In Peter the Great and the West: New Perspectives. Edited by Lindsey Hughes, 105–117. Basingstoke, UK: Palgrave Macmillan, 2001.


External links


The Baltic Sea, Kattegat and Skagerrak – sea areas and draining basins, poster with integral information by the Swedish Meteorological and Hydrological Institute



Protect the Baltic Sea while it's still not too late.

The Baltic Sea Portal
– a site maintained by the (FIMR) (in English, Finnish, Swedish and Estonian)
www.balticnest.org




in the Baltic
How the Baltic Sea was changing
– Prehistory of the Baltic from th
Polish Geological Institute


– more prehistory of the Baltic from th
Department of Geography
of the
University of Helsinki The University of Helsinki ( fi, Helsingin yliopisto, sv, Helsingfors universitet, abbreviated UH) is a public university, public Research university, research university located in Helsinki, Finland since 1829, but founded in the city of Turk ...

Baltic Environmental Atlas: Interactive map of the Baltic Sea region



List of all ferry lines in the Baltic Sea

The Helsinki Commission (HELCOM)
HELCOM is the governing body of the "Convention on the Protection of the Marine Environment of the Baltic Sea Area"
Baltice.org
– information related to winter navigation in the Baltic Sea.
Baltic Sea Wind
– Marine weather forecasts
Ostseeflug
– A short film (55'), showing the coastline and the major German cities at the Baltic sea. {{Authority control Baltic region Seas of the Atlantic Ocean European seas Geography of Central Europe Geography of Eastern Europe Geography of Northern Europe Geography of Scandinavia Seas of Germany Federal waterways in Germany Seas of Russia Seas of Denmark Bodies of water of Estonia Bodies of water of Finland Bodies of water of Lithuania Bodies of water of Poland Bodies of water of Sweden Bodies of water of Kaliningrad Oblast Bodies of water of Leningrad Oblast Bodies of water of Saint Petersburg Ecoregions of Denmark Ecoregions of Estonia Ecoregions of Finland Ecoregions of Germany Ecoregions of Latvia Ecoregions of Lithuania Ecoregions of Poland Ecoregions of Russia Ecoregions of Sweden Articles containing video clips