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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, Europe ...
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 = Kingdom of Denmark , establish ...
,
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
,
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 to the east, with the Gulf of Bot ...
,
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 betwee ...
, Latvia, Lithuania,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
,
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
,
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 and Central
European Plain The European Plain or Great European Plain is a plain in Europe and is a major feature of one of four major topographical units of Europe - the ''Central and Interior Lowlands''.
. The sea stretches from 53°N to 66°N latitude and from 10°E to 30°E longitude. A marginal sea of the Atlantic, with limited water exchange between the two water bodies, the Baltic Sea drains through the Danish Straits into the Kattegat by way of the Øresund, Great Belt and Little Belt. It includes the Gulf of Bothnia, the Bay of Bothnia, the Gulf of Finland, the Gulf of Riga and the Bay of Gdańsk. The "
Baltic Proper Baltic Proper covers the part of the Baltic Sea, from Åland Sea to the Danish sounds. Åland Sea, the Gulf of Finland and Gulf of Riga is not included. The border in the west to the Danish water is according to SMHI (Swedish Meteorological and Hyd ...
" is bordered on its northern edge, at latitude 60°N, by Åland 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 via the White Sea–Baltic Canal and to the German Bight of the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
via the Kiel Canal.


Definitions


Administration

The
Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea Area Convention on the Protection of the Marine Environment of the Baltic Sea Area, 1992 (Helsinki Convention) is an international convention encompassing various measures for the prevention and elimination of pollution of the Baltic Sea. The conventi ...
includes the Baltic Sea and the Kattegat, 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 collected Sound Dues from ships at the border between the ocean and the land-locked Baltic Sea, in tandem: in the Øresund at Kronborg castle near Helsingør; in the Great Belt at Nyborg; and in the Little Belt at its narrowest part then Fredericia, 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 Dragør () is the main town of Dragør Municipality, (Denmark), which includes the village of Store Magleby. The city hall and seat of the municipal council lies on Kirkevej 7 (postal code 2791 Dragør) in Store Magleby, which has enough space ...
in the south of Copenhagen to Malmö; it is used by the Øresund Bridge, including the ''Drogden Tunnel''. By this definition, the Danish Straits 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 Falsterbo (, outdatedly ) is a town located at the south-western tip of Sweden in Vellinge Municipality in Skåne. Falsterbo is situated in the southern part of the Falsterbo peninsula. It is part of Skanör med Falsterbo, one of Sweden's historic ...
, Sweden, and Stevns Klint, 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 and Gotland. 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 called it ''Mare Suebicum'' after the Germanic people of the Suebi, and
Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...
'' Sarmatian Ocean'' after the Sarmatians, 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 ''Gest ...
. 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 Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying degrees. Latin functioned ...
in cartography. It might be connected to the Germanic word ''belt'', a name used for two of the Danish straits,
the Belts Belt may refer to: Apparel * Belt (clothing), a leather or fabric band worn around the waist * Championship belt, a type of trophy used primarily in combat sports * Colored belts, such as a black belt or red belt, worn by martial arts practiti ...
, 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''.
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 ''Gest ...
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. Pliny mentions an island named ''
Baltia Baltia, Basilia or Abalus is a mythic island in northern Europe mentioned in Greco-Roman geography in the connection of amber. It presumably corresponds to a territory near either the Baltic Sea or the North Sea, perhaps the coast of Prussia, th ...
'' (or ''Balcia'') with reference to accounts of Pytheas and Xenophon. 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 root ''*bʰel'' meaning "white, fair", which may echo the naming of seas after colours relating to the cardinal points (as per Black Sea and Red Sea). 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 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 period of global history. It began with the fall of the Western Roman Empire ...
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 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 language ...
French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...
(''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, traditiona ...
(''Marea Baltică'') and Spanish (''Mar Báltico''); in Greek ( ''Valtikí Thálassa''); in Albanian (''Deti Balltik''); in
Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peopl ...
(''Môr Baltig''); in the Slavic languages Polish (''Morze Bałtyckie'' or ''Bałtyk''), Czech (''Baltské moře'' or ''Balt''),
Slovenian Slovene or Slovenian may refer to: * Something of, from, or related to Slovenia, a country in Central Europe * Slovene language, a South Slavic language mainly spoken in Slovenia * Slovenes, an ethno-linguistic group mainly living in Slovenia * Sl ...
(''Baltsko morje''), Bulgarian ( ''Baltijsko More''), Kashubian (''Bôłt''),
Macedonian Macedonian most often refers to someone or something from or related to Macedonia. Macedonian(s) may specifically refer to: People Modern * Macedonians (ethnic group), a nation and a South Slavic ethnic group primarily associated with North Ma ...
(Балтичко Море ''Baltičko More''),
Ukrainian Ukrainian may refer to: * Something of, from, or related to Ukraine * Something relating to Ukrainians, an East Slavic people from Eastern Europe * Something relating to demographics of Ukraine in terms of demography and population of Ukraine * So ...
( ''Baltijs′ke More''), Belarusian (Балтыйскае мора ''Baltyjskaje Mora''), Russian ( ''Baltiyskoye More'') and Serbo-Croatian (''Baltičko more'' / ); in Hungarian (Balti-tenger). * In
Germanic languages The Germanic languages are a branch of the 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 Germanic language, ...
, 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 enslaved people. Afrikaans gr ...
(''Oossee''), Danish (''Østersøen'' ), Dutch (''Oostzee''),
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
(''Ostsee''), Low German ''(Oostsee)'', Icelandic and Faroese (''Eystrasalt''), Norwegian ( Bokmål: ''Østersjøen'' ; Nynorsk: ''Austersjøen''), and Swedish (''Östersjön''). In
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th ...
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 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 mi ...
, 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 word-for-word or root-for-root translation. When used as a verb, "to calque" means to borrow a word or phrase from another language ...
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 Estonian may refer to: * Something of, from, or related to Estonia, a country in the Baltic region in northern Europe * Estonians, people from Estonia, or of Estonian descent * Estonian language * Estonian cuisine * Estonian culture See also * ...
, 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 in his AD 98 ''Agricola'' and ''Germania'' described the Mare Suebicum, named for the Suebi tribe, during the spring months, as a brackish 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.
Jordanes Jordanes (), also written as Jordanis or Jornandes, was a 6th-century Eastern Roman bureaucrat widely believed to be of Gothic descent who became a historian later in life. Late in life he wrote two works, one on Roman history ('' Romana'') an ...
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 by Jordanes in or shortly after 551 AD, claims to be a summary of a voluminous account by Cassiodorus of th ...
''.


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 period of global history. It began with the fall of the Western Roman Empire ...
, 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 transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
for trade routes, finding their way eventually to the Black Sea 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'' and ''Eystra salt'' appears in '' Sörla þáttr''. Saxo Grammaticus recorded in '' Gesta Danorum'' an older name, ''
Gandvik In Norse mythology, Gandvík is a dangerous sea, known as the "Bay of Serpents" because of its tortuous shape. The 12th-13th century Dane Saxo Grammaticus stated that Gandvik was an old name for the Baltic Sea (a name misspelt Grandvik in some tra ...
'', ''-vik'' being
Old Norse Old Norse, Old Nordic, or Old Scandinavian, is a stage of development of North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia and their overseas settlement ...
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, 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, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
,
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
and 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, flax, hemp and furs by ship across the Baltic. Sweden had from early medieval times exported
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
and
silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
mined there, while Poland had and still has extensive salt 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 monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion with roughly 2.38 billion followers representing one-third of the global popula ...
. This finally happened during the Northern Crusades:
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 to the east, with the Gulf of Bot ...
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. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
and Latvia in the early thirteenth century by Danes and Germans ( Livonian Brothers of the Sword). The Teutonic Order gained control over parts of the southern and eastern shore of the Baltic Sea, where they set up their monastic state. 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, and the Victual Brothers held Gotland. 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 betwee ...
, a movement called the '' Ostsiedlung'' ("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 Netherl ...
,
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 = Kingdom of Denmark , establish ...
, and
Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...
. The Polabian Slavs 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 = Kingdom of Denmark , establish ...
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, 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 on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
. 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, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
,
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 = Kingdom of Denmark , establish ...
, 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 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 transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
and Prussia became the leading powers over the sea. Sweden's defeat in the Great Northern War brought Russia to the eastern coast. Russia became and remained a dominating power in the Baltic. Russia's Peter the Great 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 , ...
river at the east end of the Gulf of Finland. There was much trading not just within the Baltic region but also with the North Sea region, especially eastern
England England is a 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 separated from continental Europe ...
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 Netherl ...
: their fleets needed the Baltic timber, tar, flax, and hemp. During the Crimean War, 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; and Kronstadt, which guards Saint Petersburg; and they destroyed Bomarsund in Åland. 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 betwee ...
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, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
was granted access to the Baltic Sea at the expense of Germany by the Polish Corridor and enlarged the port of Gdynia in rivalry with the port of the Free City of Danzig. After the Nazis' rise to power, Germany reclaimed the Memelland and after the outbreak of the Eastern Front (World War II) 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 Wilhelm Gustloff (30 January 1895 – 4 February 1936) was the founder of the Swiss NSDAP/AO (the Nazi Party organisation for German citizens living outside Germany) at Davos. He remained its leader from 1932 until he was assassinated in 1936. ...
'' 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 transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
, the United Kingdom and the United States have disposed of chemical weapons 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 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 Making Room is an approach to housing policy that seeks to match a city's housing stock with the needs of its households. It was coined in 2009 by Citizens Housing and Planning Council (CHPC), a New York City-based research and education organizat ...
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 subject of Russia. It is a semi-exclave situated on the Baltic Sea. The largest city and admin ...
, that had been part of German-settled East Prussia. 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 military alliance between 30 member states – 28 European and two N ...
and the
Warsaw Pact The Warsaw Pact (WP) or Treaty of Warsaw, formally the Treaty of Friendship, Cooperation and Mutual Assistance, was a collective defense treaty signed in Warsaw, Poland, between the Soviet Union and seven other Eastern Bloc socialist republi ...
. Neutral Sweden developed
incident weapon An incident weapon is typically an anti-vehicle device intended to inflict disabling damage or prevent escape without killing the vehicle operators. Incident weapons were used by military personnel during the Cold War to discourage clandestine use ...
s to defend its territorial waters after the
Swedish submarine incidents The submarine hunts or submarine incidents were a series of several incidents involving foreign submarines that occurred in Swedish territorial waters during the Cold War, attributed in Swedish media to the Soviet Union. On October 27, 1981, the ...
. This border status restricted trade and travel. It ended only after the collapse of the Communist 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 subject of Russia. It is a semi-exclave situated on the Baltic Sea. The largest city and admin ...
exclave. Winter storms begin arriving in the region during October. These have caused numerous shipwrecks, and contributed to the extreme difficulties of rescuing passengers of the ferry '' M/S Estonia'' en route from Tallinn, Estonia, to
Stockholm Stockholm () is the capital and largest city of Sweden as well as the largest urban area in Scandinavia. Approximately 980,000 people live in the municipality, with 1.6 million in the urban area, and 2.4 million in the metropo ...
, 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 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 The All Saints Day flood (german: Allerheiligenflut) of 1304 was a storm surge that hit the southwestern Baltic Sea coast on 1 November (All Saints' Day) that year. The region of Western Pomerania was particularly badly affected by the flooding. 27 ...
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 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 = Kingdom of Denmark , establish ...
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 to the east, with the Gulf of Bot ...
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, Latvia, and Lithuania. All three countries are members of NATO, the European Union, the 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 inland seas by area, and occupies a basin (a '' Zungenbecken'') formed by glacial erosion during the last few ice ages.


Extent

The International Hydrographic Organization 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.'' A line joining Falshöft () and Vejsnæs Nakke ( Ærø: ). :*''In the Great Belt.'' A line joining Gulstav (South extreme of Langeland Island) and Kappel Kirke () on Island of Lolland. :*''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, of which the northernmost part is the Bay of Bothnia or Bothnian Bay. The more rounded southern basin of the gulf is called
Bothnian Sea The Bothnian Sea ( sv, Bottenhavet; fi, Selkämeri) links the Bothnian Bay (also called the Bay of Bothnia) with the Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, th ...
and immediately to the south of it lies the Sea of Åland. The Gulf of Finland 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 lies between the Latvian capital city of Riga and the
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
n island of Saaremaa. The Northern Baltic Sea lies between the
Stockholm Stockholm () is the capital and largest city of Sweden as well as the largest urban area in Scandinavia. Approximately 980,000 people live in the municipality, with 1.6 million in the urban area, and 2.4 million in the metropo ...
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 Basin is the area east of Bornholm, and the shallower Arkona Basin extends from Bornholm to the Danish isles of Falster and Zealand. In the south, the Bay of Gdańsk lies east of the
Hel Peninsula Hel Peninsula (; pl, Mierzeja Helska, Półwysep Helski; csb, Hélskô Sztremlëzna; german: Halbinsel Hela or ''Putziger Nehrung'') is a sand bar peninsula in northern Poland separating the Bay of Puck from the open Baltic Sea. It is l ...
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 subject of Russia. It is a semi-exclave situated on the Baltic Sea. The largest city and admin ...
. The Bay of Pomerania lies north of the islands of Usedom/Uznam and Wolin, east of Rügen. 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 Great Belt, the Little Belt and The Sound (''Öresund''/''Øresund''), connect the Baltic Sea with the Kattegat and Skagerrak strait in the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
.


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 climates, but adjacent to the water continental climates are common, especially on the Gulf of Finland. In the northern tributaries the climates transition from moderate continental to subarctic 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 Finland, the Gulf of Riga, 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 ice reaches its maximum extent in February or March; typical ice thickness in the northernmost areas in the Bothnian Bay, 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 Bothnian Sea ( sv, Bottenhavet; fi, Selkämeri) links the Bothnian Bay (also called the Bay of Bothnia) with the Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, th ...
, the basin south of Kvarken, 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. According to the 18th-century natural historian William Derham, 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, 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. This was brought about by a stagnant high-pressure area 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 Świnoujście (; german: Swinemünde ; nds, Swienemünn; all three meaning "Świna ivermouth"; csb, Swina) is a city and seaport on the Baltic Sea and Szczecin Lagoon, located in the extreme north-west of Poland. Situated mainly on the islands ...
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, which is attached to the shoreline, develops first, rendering ports unusable without the services of icebreakers.
Level ice Level or levels may refer to: Engineering *Level (instrument), a device used to measure true horizontal or relative heights *Spirit level, an instrument designed to indicate whether a surface is horizontal or vertical *Canal pound or level *Regr ...
,
ice sludge Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...
, pancake ice, and
rafter ice A rafter is one of a series of sloped structural members such as wooden beams that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof shingles, roof deck and its associate ...
form in the more open regions. The gleaming expanse of ice is similar to the Arctic, 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, 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 remnants of ice were observed as late as 17 July near Uddskär. Even as far south as Øresund, 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 (''Halichoerus grypus'') and the Baltic ringed seal (''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; 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 on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
. Due to the difference in salinity, 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, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
. 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 Vistula, 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 , ...
. 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, sleet, snow, ice pellets, graupel and hail. ...
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 on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
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 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 on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
. 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 sea. Only two other brackish waters are larger according to some measurements: The Black Sea is larger in both surface area and water volume, but most of it is located outside the continental shelf (only a small fraction is inland). The Caspian Sea is larger in water volume, but—despite its name—it is a lake rather than a sea. The Baltic Sea's salinity 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. 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 and Bornholm, and the latter directly east of Bornholm). It gradually falls further east and north, reaching the lowest in the Bothnian Bay 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 In oceanography, a halocline (from Greek ''hals'', ''halos'' 'salt' and ''klinein'' 'to slope') is a cline, a subtype of chemocline caused by a strong, vertical salinity gradient within a body of water. Because salinity (in concert with te ...
, that represents a barrier to the exchange of
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
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, 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 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, 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 (
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 to the east, with the Gulf of Bot ...
, autonomous) *
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 to the east, with the Gulf of Bot ...
) ** Pargas ** Nagu ** Korpo ** Houtskär ** Kustavi **
Kimito Kimito (; fi, Kemiö ) is a 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, it was one of the four municipalities ...
* 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, including
Christiansø Ertholmene (formerly spelled ''Ærtholmene)'' is a small archipelago in Denmark. The largest island is Christiansø, and its name often refers to the entire archipelago. Ertholmene is situated northeast of Gudhjem, Bornholm, and contains De ...
(
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 = Kingdom of Denmark , establish ...
) * Falster (
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 = Kingdom of Denmark , establish ...
) * Gotland (
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 (
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 to the east, with the Gulf of Bot ...
) * Kotlin (
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
) * Lolland (
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 = Kingdom of Denmark , establish ...
) * Kvarken 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 to the east, with the Gulf of Bot ...
) * 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 = Kingdom of Denmark , establish ...
) * Öland (
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 (
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 betwee ...
) * 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 Szczeci ...
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 betwee ...
and
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
) * West Estonian archipelago (
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
): ** Hiiumaa ** Muhu ** Saaremaa ** Vormsi * Wolin (
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
) * Zealand (
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 = Kingdom of Denmark , establish ...
)


Coastal countries

Countries that border the sea: Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden. Countries lands in the outer drainage basin: 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 and largest city of Sweden as well as the largest urban area in Scandinavia. Approximately 980,000 people live in the municipality, with 1.6 million in the urban area, and 2.4 million in the metropo ...
(Sweden) 962,154 (metropolitan area 2,315,612) * Helsinki (Finland) 658,864 (metropolitan area 1,536,810) * Riga (Latvia) 614,618 (metropolitan area 1,070,00) * Gdańsk (Poland) 462,700 (
metropolitan area A metropolitan area or metro is a region that consists of a densely populated urban agglomeration and its surrounding territories sharing industries, commercial areas, transport network, infrastructures and housing. A metro area usually ...
1,041,000) * Tallinn (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 (Poland) 413,600 (metropolitan area 778,000) * Gdynia (Poland) 255,600 (
metropolitan area A metropolitan area or metro is a region that consists of a densely populated urban agglomeration and its surrounding territories sharing industries, commercial areas, transport network, infrastructures and housing. A metro area usually ...
1,041,000) *
Espoo Espoo (, ; sv, Esbo) is a city and municipality in the region of Uusimaa in the Republic of Finland. It is located on the northern shore of the Gulf of Finland, bordering the cities of Helsinki, Vantaa, Kirkkonummi, Vihti and Nurmijärv ...
(Finland) 257,195 (part of Helsinki metropolitan area) * Kiel (Germany) 247,000 * Lübeck (Germany) 216,100 * Rostock (Germany) 212,700 * Klaipėda (Lithuania) 194,400 * Oulu (Finland) 191,050 * Turku (Finland) 180,350 Other important ports: * ''Estonia:'' ** Pärnu 44,568 ** Maardu 16,570 ** Sillamäe 16,567 * ''Finland:'' ** Pori 83,272 ** Kotka 54,887 ** Kokkola 46,809 **
Port of Naantali The Port of Naantali ( fi, Naantalin satama, sv, Nådendal hamn) is a port located in the south-west of Finland, city of Naantali, where the mainland meets the beginning of the Turku archipelago. The port is among the largest in Finland in term ...
18,789 ** Mariehamn 11,372 ** Hanko 9,270 * ''Germany:'' ** Flensburg 94,000 ** Stralsund 58,000 ** Greifswald 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 cit ...
44,000 ** Eckernförde 22,000 ** Neustadt in Holstein 16,000 ** Wolgast 12,000 ** Sassnitz 10,000 * ''Latvia:'' ** Liepāja 85,000 ** Ventspils 44,000 * ''Lithuania:'' ** Palanga 17,000 * ''Poland:'' ** Kołobrzeg 44,800 **
Świnoujście Świnoujście (; german: Swinemünde ; nds, Swienemünn; all three meaning "Świna ivermouth"; csb, Swina) is a city and seaport on the Baltic Sea and Szczecin Lagoon, located in the extreme north-west of Poland. Situated mainly on the islands ...
41,500 ** Police 34,284 **
Władysławowo Władysławowo ( Kashubian/ Pomeranian: ''Wiôlgô Wies'', german: Großendorf) is a city on the south coast of the Baltic Sea in Kashubia in the Pomerelia region, northern Poland, with 15,015 (2009) inhabitants. History In 1634 engineer Fr ...
15,000 ** Darłowo 14,000 * ''Russia:'' ** Vyborg 79,962 ** Baltiysk 34,000 * ''Sweden:'' ** Norrköping 84,000 ** Gävle 75,451 ** Trelleborg 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 ...
bed, with two tributaries, the Gulf of Finland and Gulf of Bothnia. Geological surveys show that before the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), 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 fina ...
, instead of the Baltic Sea, there was a wide plain around a great river that paleontologists call the Eridanos. Several Pleistocene glacial episodes scooped out the river bed into the sea basin. By the time of the last, or Eemian Stage (
MIS MIS or mis may refer to: Science and technology * Management information system * Marine isotope stage, stages of the Earth's climate * Maximal independent set, in graph theory * Metal-insulator-semiconductor, e.g., in MIS capacitor * Minimally i ...
 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 environm ...
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 ''Littorina'' is a genus of small sea snails, marine gastropod molluscs in the family Littorinidae, the winkles or periwinkles.WoRMS (2011). Littorina Férussac, 1822. Accessed through: World Register of Marine Species at http://www.marines ...
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 species of molluscs are recognized. The number of fossil species is e ...
) 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 on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...
- Atlantic, 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 = Kingdom of Denmark , establish ...
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-
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 The Eemian Sea was a body of water located approximately where the Baltic Sea is now during the last interglacial, or Eemian Stage, Marine isotopic stage (MIS) 5e, roughly 130,000 to 115,000 years BP. Sea level was 5 to 7 metres higher globall ...
, 130,000–115,000 ( years ago) *
Baltic Ice Lake The Baltic Ice Lake is a name given by geologists to a freshwater lake that evolved in the Baltic Sea basin as glaciers retreated from that region at the end of the last ice age. The lake existed between 12,600 and 10,300 years Before Present ...
, 12,600–10,300 *
Yoldia Sea Yoldia Sea is a name given by geologists to a variable brackish water stage in the Baltic Sea basin that prevailed after the Baltic Ice Lake was drained to sea level during the Weichselian glaciation. Dates for the Yoldia sea are obtained mainly ...
, 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 The Mastogloia Sea is one of the prehistoric stages of the Baltic Sea in its development after the last ice age. This took place 8000 years ago following the Ancylus Lake stage and preceding the Littorina Sea stage. Overview Towards its demise, ...
, 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. 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 navigate, measure distances (ranging), communicate with or detect objects on 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.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,
Atlantic herring Atlantic herring (''Clupea harengus'') is a herring in the 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 schools. They can ...
, 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 seas.
and turbot, and examples of freshwater species include European perch, northern pike, 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, 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 The common starfish, common sea star or sugar starfish (''Asterias rubens'') is the most common and familiar starfish in the north-east Atlantic. Belonging to the family Asteriidae, it has five arms and usually grows to between 10–30  ...
and
shore crab ''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name europ ...
, 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 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 tides 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 being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
species: the brown alga '' Fucus radicans'' and the flounder ''
Platichthys solemdali The Baltic flounder (''Platichthys solemdali'') is a species of flatfish endemic to the Baltic Sea, where it is the only known endemic fish species. It is sympatric with the closely related European flounder (''P. flesus''), which it looks ident ...
''. 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'' is a species of mollusc, known as Copenhagen cockle. It is an endemic species to the Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuan ...
(''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 cockle ''Cerastoderma glaucum'', the lagoon cockle, is a species of saltwater clam, a marine bivalve mollusc in the family Cardiidae, the cockles. This species is found along the coasts of Europe and North Africa, including the Mediterranean and Blac ...
s (''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 bet ...
, such as the large isopod ''
Saduria entomon ''Saduria entomon'' is a benthic isopod crustacean of the family Chaetiliidae. It is distributed along the coasts of the Arctic Ocean and of the northern Pacific Ocean. It is also found in the brackish Baltic Sea, where it is considered a glaci ...
'', the Baltic subspecies of ringed seal, and the fourhorn sculpin. Some of these relicts are derived from glacial lakes, such as ''
Monoporeia affinis ''Monoporeia affinis'', formerly referred to as ''Pontoporeia affinis'' ( el, Πόντος, ' = Pontus / Black Sea; , ' = to travel), is a small, yellowish benthic amphipod living in the Baltic Sea, the Arctic Sea and the lakes of the Nordic co ...
'', which is a main element in the
benthic fauna Benthos (), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone.Bothnian Bay. Cetaceans in the Baltic Sea are monitored by the countries bordering the sea and data compiled by various intergovernmental bodies, such as ASCOBANS. A critically endangered population of harbor porpoise inhabit the Baltic proper, whereas the species is abundant in the outer Baltiuc (Western Baltic and Danish Straits) and occasionally oceanic and out-of-range species such as minke whales, bottlenose dolphins, beluga whales, orcas, and
beaked whale Beaked whales ( systematic name Ziphiidae) are a 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 reasonably well- ...
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 parvorder of baleen whales. It is the second-longest species of ceta ...
s and humpback whales migrate into Baltic sea including mother and calf pair. Now extinct Atlantic grey whales (remains found from Gräsö along
Bothnian Sea The Bothnian Sea ( sv, Bottenhavet; fi, Selkämeri) links the Bothnian Bay (also called the Bay of Bothnia) with the Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, th ...
/southern
Bothnian Gulf The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost arm of the Baltic Sea, between Finland's west coast ( East Bothnia) and the Sweden's east coast ( Wes ...
and Ystad) and eastern population of North Atlantic right whales that is facing functional extinction once migrated into Baltic Sea. Other notable megafauna include the basking sharks.


Environmental status

Satellite images taken in July 2010 revealed a massive algal bloom 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 and phosphorus. It has also been defined as "nutrient-induced increase in phyt ...
. 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 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, precisely the Zealand). 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 t ...
. Much shipbuilding is carried out in the shipyards around the Baltic Sea. The largest shipyards are at Gdańsk, Gdynia, and Szczecin, Poland; Kiel, Germany; Karlskrona and Malmö, Sweden; Rauma, Turku, and Helsinki, Finland; Riga, Ventspils, 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,
Silja Line Silja Line is a Swedish-Finnish cruiseferry brand operated by the Estonian ferry company Tallink, AS Tallink Grupp, for car, cargo and passenger traffic between Finland and Sweden. The former company Silja Oy—today Tallink Silja osakeyhtiö, O ...
, Polferries, the Viking Line,
Tallink Tallink () is an Estonian shipping company operating Baltic Sea cruiseferries and ropax ships from Estonia to Finland, Estonia to Sweden to Sweden and Finland to Sweden. It is the largest passenger and cargo shipping company in the Baltic Se ...
, 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, cross ...
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 municipality on the island of Usedom on the Baltic coast. It is the easternmost of the so-called ''Kaiserbäder'' ("Imperial Spas") seaside resorts on the German part of the island, situated ...
, Germany *
Bansin Bansin forms the westernmost part of the seaside resort town of Heringsdorf in Mecklenburg-Western Pomerania, Germany, on the east coast of Usedom island, about five miles by rail northwest of Świnoujście. Bansin is one of the most popular resor ...
, Germany * Binz, Germany * Heiligendamm, Germany * Kühlungsborn, Germany *
Sellin Sellin is a municipality on the Island of Rügen, in Mecklenburg-Vorpommern, Germany. History First mentions of Sellin date to 1295. From 1880 on, the town gained importance as a Baltic Sea spa town. After the '' Wende'' in 1989, the buildin ...
, Germany * Liepāja, Latvia *
Šventoji, Lithuania Šventoji is a small resort town on the coast of the Baltic Sea in Lithuania. Administratively it is part of Palanga City Municipality. The total population of Šventoji as of 2012 was 2631. The town is located about 12 km north of Palanga c ...
* Klaipėda, Lithuania * Gdańsk, Poland * Gdynia, Poland * Kołobrzeg, Poland * Misdroy, Poland * Sopot, Poland Resort towns * Haapsalu, Estonia *
Kuressaare Kuressaare () is a 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 January 2018 was 13,276. ...
, Estonia *
Narva-Jõesuu Narva-Jõesuu (; russian: Усть-Нарва, ''Ust'-Narva'', Нарва-Йыэсуу, Усть-Нарова) is a town in Ida-Viru County, in northeastern Estonia. Geography It is located on the country's northern Baltic coast of the Gulf ...
, Estonia * Pärnu, Estonia * Hanko, Finland * Mariehamn, Finland * Binz, Germany * Heiligendamm, Germany *
Heringsdorf Heringsdorf is a semi-urban municipality and a popular seaside resort on Usedom Island in Western Pomerania, Germany. It is also known by the name Kaiserbad ('' en, Imperial Spa''). The municipality was formed in January 2005 out of the former ...
, Germany * Travemünde, Germany *
Sellin Sellin is a municipality on the Island of Rügen, in Mecklenburg-Vorpommern, Germany. History First mentions of Sellin date to 1295. From 1880 on, the town gained importance as a Baltic Sea spa town. After the '' Wende'' in 1989, the buildin ...
, Germany *
Ueckermünde Ueckermünde () is a seaport town in northeast Germany, located in the district of Vorpommern-Greifswald, Western Pomerania, near Germany's border with Poland's Police County. Ueckermünde has a long and varied history, going back to its fo ...
, Germany * Jūrmala, Latvia * Nida, Lithuania * Palanga, Lithuania *
Šventoji, Lithuania Šventoji is a small resort town on the coast of the Baltic Sea in Lithuania. Administratively it is part of Palanga City Municipality. The total population of Šventoji as of 2012 was 2631. The town is located about 12 km north of Palanga c ...
* Juodkrantė, Lithuania *
Pervalka Pervalka (Kursenieki: ''Pērvelka'', german: Perwelk) is a small settlement located on the Curonian Spit in Klaipėda County, Lithuania. Administratively, it is part of the city of Neringa. It is located north from Preila and south of Juodkran ...
, Lithuania * Karklė, Lithuania * Kamień Pomorski, Poland * Kołobrzeg, Poland * Sopot, Poland *
Świnoujście Świnoujście (; german: Swinemünde ; nds, Swienemünn; all three meaning "Świna ivermouth"; csb, Swina) is a city and seaport on the Baltic Sea and Szczecin Lagoon, located in the extreme north-west of Poland. Situated mainly on the islands ...
, Poland * Ustka, Poland *
Svetlogorsk Svetlogorsk may refer to: * Svetlogorsk Urban Settlement, several municipal urban settlements in Russia *Svetlogorsk, Russia, several inhabited localities in Russia *Svietlahorsk , nickname = Svietly (The Bright), , image_skyline ...
, 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 *
Baltic Sea Action Group The Baltic Sea Action Group (BSAG) is an independent foundation that does concrete work on behalf of the Baltic Sea, one of the most polluted seas in the world. BSAG is based in Helsinki, Finland but it operates throughout the entire Baltic Sea a ...
(BSAG) * Council of the Baltic Sea States * List of cities and towns around the Baltic Sea *
List of rivers of the Baltic Sea This is a list of rivers that drain into the Baltic Sea (clockwise from Öresund): Sweden * Svartån (at Svarte near Ystad) * Tommarpaån (at Simrishamn) * Helgeå (at Nyehusen near Kristianstad) * Hemån (at Karlskrona) * Ljungbyån (at Ljun ...
* Nord Stream 1 * Nord Stream 2 * Northern Europe * Ports of the Baltic Sea *
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and S ...


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 research university located in Helsinki, Finland since 1829, but founded in the city of Turku (in Swedish ''Åbo'') in 1640 as the R ...

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