The Skagerrak (, , ) is a

strait A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean chan ...

running between the Jutland peninsula 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 ...

, the southeast coast of

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...

and the west coast 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 ...

, connecting 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 ...

and the Kattegat sea area through the Danish Straits to the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...

. The Skagerrak contains some of the busiest shipping routes in the world, with vessels from every corner of the globe. It also supports an intensive fishing industry. The ecosystem is strained and negatively affected by direct human activities.

Oslo Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of ...

and

Gothenburg Gothenburg (; abbreviated Gbg; sv, Göteborg ) is the second-largest city in Sweden, fifth-largest in the Nordic countries, and capital of the Västra Götaland County. It is situated by the Kattegat, on the west coast of Sweden, and has ...

are the only large cities in the Skagerrak region.

Name

The meaning of ''Skagerrak'' is most likely the Skagen Channel/Strait. Skagen is a town near the northern cape of Denmark (The Skaw). ''Rak'' means 'straight

waterway A waterway is any navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other languages. A first distinction is necessary ...

' (compare the Damrak in Amsterdam); it is cognate with ''

reach Reach or REACH may refer to: Companies and organizations * Reach plc, formerly Trinity Mirror, large British newspaper, magazine, and digital publisher * Reach Canada, an NGO in Canada * Reach Limited, an Asia Pacific cable network company ...

''.Nudansk Ordbog (1993), 15th edition, 2nd reprint, Copenhagen: Politikens Forlag, entry ''Skagerrak''. The ultimate source of this syllable is the

Proto-Indo-European Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. Its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. No direct record of Proto-Indo ...

root *reg-, 'straight'. ''Rak'' means 'straight' as in 'straight ahead' in modern Norwegian and Swedish. ''Råk'' in both modern Norwegian and Swedish refers to a channel or opening of water in an otherwise ice-covered body of water. There is no evidence to suggest a connection with the modern Danish word ''rak'' (meaning rabble or riff-raff). Another possibility is that the Skagerrak was named by Dutch seafarers, in the same way the adjacent Kattegat got its name. It was quite common for the Dutch to call similar stretches of waterways a ''rak'', such as: Langerak, Damrak, Gouderak, and Tuikwerderrak. (See Kattegat for its etymology, in which ''gat'' means "gate" or "hole".)

Geography

The Skagerrak is long and between wide. It deepens toward the Norwegian coast, reaching over 700 m at the Norwegian Trench. Some ports along the Skagerrak are

, Larvik and

Kristiansand Kristiansand is a seaside resort city and municipality in Agder county, Norway. The city is the fifth-largest and the municipality the sixth-largest in Norway, with a population of around 112,000 as of January 2020, following the incorporati ...

, Skagen, Hirtshals and Hanstholm in

and Uddevalla, Lysekil and Strömstad in

. The Skagerrak has an average salinity of 80

practical salinity unit Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

s, which is very low, close to that of brackish water, but comparable to most other coastal waters. The area available to biomass is about and includes a wide variety of habitats, from shallow sandy and stony

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes—deposition of sand, wave erosion planing down rock ...

s in Sweden and Denmark to the depths of the Norwegian trench.

Extent

The

International Hydrographic Organization The International Hydrographic Organization (IHO) is an intergovernmental organisation representing hydrography. , the IHO comprised 98 Member States. A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters ...

defines the limits of the Skagerrak as follows:

''On the West.'' A line joining Hanstholm () and the Naze ( Lindesnes, ). ''On the Southeast.'' The Northern limit of the Kattegat Skagen_(The_Skaw,_North_Point_of_Denmark)_and_Paternosterskären_()_and_thence_Northeastward_through_the_shoals_to_Tjörn_Municipality.html" ;"title=" line joining Skagen (The Skaw, North Point of Denmark) and Paternosterskären () and thence Northeastward through the shoals to Tjörn Municipality">Tjörn Island].

History

Older names for the combined Skagerrak and Kattegat were the ''Norwegian Sea'' or ''Jutland Sea''; the latter appears in the Knýtlinga saga. Until the construction of the Eider Canal in 1784 (a predecessor to the Kiel Canal), Skagerrak was the only way in and out of the

. For this reason the strait has had a busy international traffic for centuries. After the

Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

, the traffic increased and today Skagerrak is among the busiest straits in the world. In 1862, a short cut, the

Thyborøn Channel Thyborøn is a fishing village in Jutland, Denmark with a population of 1,890 (1 January 2022),Limfjord was constructed in Denmark through Skagerrak from the North Sea by going directly to the Kattegat. The Limfjord supports only minor transports though. In both world wars, the Skagerrak was strategically very important for

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 ...

. The biggest sea battle of the

First World War 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, ...

, the Battle of Jutland, also known as the Battle of the Skagerrak, took place here May 31 to June 1, 1916. In the

Second World War 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 vast majority of the world's countries—including all of the great powers—forming two opposi ...

, the importance of controlling this waterway, the only sea access to the Baltic, was the motive for the German invasions of

and the construction of the northern parts of the

Atlantic Wall The Atlantic Wall (german: link=no, Atlantikwall) was an extensive system of coastal defences and fortifications built by Nazi Germany between 1942 and 1944 along the coast of continental Europe and Scandinavia as a defence against an anticip ...

. Both of these naval engagements have contributed to the large number of shipwrecks in the Skagerrak.

Traffic and industry

Skagerrak is a heavily trafficated strait, with c. 7,500 individual vessels (excluding fishing vessels) from all over the world visiting in 2013 alone. Cargo ships are by far the most common vessel in Skagerrak at c. 4,000 individual ships in 2013, followed by tankers, which are nearly half as frequent. When viewed in combination with the Baltic Sea area, ships from 122 different nationalities visited in 2013, with most of these carrying cargo or passengers within Europe, regardless of their flag state. Nearly all commercial vessels in Skagerrak are tracked by the Automatic Identification System (AIS).

Recreation

Skagerrak is popular for recreational activities in all three countries. There are many summer house residences and several marinas along the coasts.

Biology

The Skagerrak is habitat for approximately 2,000 marine species, many of them adapted to its waters. For example, a variety of Atlantic cod called the Skagerrak cod spawns off the Norwegian coast. The eggs are buoyant and the hatchlings feed on zooplankton. Juveniles sink to the bottom where they have a shorter maturity cycle (2 years). They do not migrate but remain local to Norwegian

fjord In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Icel ...

s. The variety of habitats and the large volume of

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

on the surface support prolific marine life. Energy moves from the top to the bottom according to Vinogradov's ladder of migrations; that is, some species are benthic and others

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

, but there are graded marine layers within which species move vertically for short distances. In addition, some species are benthopelagic, moving between surface and bottom. The benthic species include '' Coryphaenoides rupestris'', '' Argentina silus'', '' Etmopterus spinax'', ''

Chimaera monstrosa ''Chimaera monstrosa'', also known as the rabbit fish or rat fish, is a northeast Atlantic and Mediterranean species of cartilaginous fish in the family Chimaeridae. The rabbit fish is known for its characteristically large head and small, tap ...

'' and '' Glyptocephalus cynoglossus''. On the top are ''

Clupea harengus 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 ...

'', '' Scomber scombrus'', ''

Sprattus sprattus The European sprat (''Sprattus sprattus''), also known as bristling, brisling, garvie, garvock, Russian sardine, russlet, skipper or whitebait, is a species of small marine fish in the herring family Clupeidae. Found in European waters, it has si ...

''. Some species that move between are '' Pandalus borealis'', '' Sabinea sarsi'', '' Etmopterus spinax''.

Reefs

Apart from sandy and stony reefs, extensive cold water

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...

s, mostly of '' Lophelia'', are growing in Skagerrak. The Säcken Reef in the Swedish marine protection of Koster Fjord is an ancient cold water coral reef and the only known coral reef in the country. The Tisler Reef in the Norwegian marine protection of

Ytre Hvaler National Park Ytre Hvaler National Park ( no, Ytre Hvaler nasjonalpark, literally ''Outer Hvaler National Park'') is a national park located within the municipalities of Hvaler and Fredrikstad in Østfold, Norway. The park was established on 26 June 2009 and ...

is the largest known coral reef in Europe. Lophelia reefs are also present in the Norwegian trench and they are known from the shallow waters of many Norwegian fjords. Skagerrak also holds a number of rare bubble reefs; biological reefs formed around cold seeps of geological carbohydrate outgassings, usually

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane ...

. These rare habitats are mostly known from the Danish waters of Skagerrak west of Hirtshals, but more might be discovered in future surveys. Bubbly reefs are very rare in Europe and supports a very varied ecosystem. With the centuries long heavy international seatraffic of Skagerrak, the seabed also holds an abundance of shipwrecks. Wrecks on shallow waters, provides a firm anchoring for several corals and polyps and explored wrecks have been revealed to support Dead Man's Fingers corals, Brittle stars and large

wolffish Anarhichadidae, the wolffishes, sea wolves or wolf eels, is a family of marine ray finned fishes belonging to the order Scorpaeniformes. These are predatory, eel shaped fishes which are native to the cold waters of the Arctic, North Pacific and ...

. A 2020 seafloor mapping project around Jammerbugten in Skaggerak, ran by danish explorer Klaus Thymann, found evidence of much greater biodiversity in a range seafloor habitats previously thought to be sandy with a low density of wildlife. Dead Man’s Fingers corals were again among the species documented for the first time in these coastal habitats.

Environmental concerns

Scientists and environmental institutions have expressed concern about the increasing pressure on the

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

in Skagerrak. The pressure has already had negative impacts and is caused by cumulative environmental effects, of which direct human activities are only one piece of the puzzle.

Climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

and

ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...

are expected to have increasing impacts on the Skagerrak ecosystem in the future. Skagerrak and the North Sea receives considerable inputs of hazardous material and radioactive substances. Most is ascribed to long-range transport from other countries, but not all. Marine litter is also a growing problem. Until recently, waste water and sewage pouring into Skagerrak from settlements and industries was not treated at all. In combination with wash out of excessive nutrients from conventional farming, this has often led to large algae blooms.

Protections

There are several marine protections in Skagerrak, including: ;Norway *

, established on 26 June 2009 * Raet National Park, established on 16 December 2016 ;Sweden * Kosterhavet National Park * Bratten, a newly designated Natura 2000 sea area beyond Kosterhavet. Pockmarks and biogenic reefs at depths of . *

Gullmarsfjorden Gullmarn, also known as Gullmarsfjorden or Gullmaren, is a threshold fjord in the middle of Bohuslän Archipelago on the west coast of Sweden. It is the largest of the Bohuslän fjords with a length of and a width ranging from . At its mouth, t ...

, Sweden's first marine conservation area from 1983. ;Denmark *

Grenen Grenen is a long sandbar spit at Skagen Odde (the headland of Jutland), north of the town of Skagen. Overview ''Grenen'' (The Branch) was named for its shape like a tree-branch, reaching out from the mainland. The beach of Grenen appears in ma ...

and a sea area immediately north.

Notes and references

External links

The Baltic Sea, Kattegat and Skagerrak
Swedish Meteorological and Hydrological Institute (SMHI).
Skagerrak Deep-water Fish Assemblage

Marine vessel Traffic {{Authority control Denmark–Sweden border International straits Landforms of Västra Götaland County Norway–Sweden border Straits of Denmark Straits of Norway Straits of Sweden