The Skagerrak is a habitat for approximately 2,000 marine species, including a unique variety of Atlantic cod.

Environmental institutions have expressed concern about increasing pressure on the ecosystem due to human activities and climate change.

There is no evidence to suggest a connection with the modern Danish word rak (meaning rabble or riff-raff).

Some ports along the Skagerrak are Oslo, Larvik and Kristiansand in Norway, Skagen, Hirtshals and Hanstholm in Denmark and Uddevalla, Lysekil and Strömstad in Sweden.

The area available to biomass is about 3,600 km2 (1,400 sq mi) and includes a wide variety of habitats, from shallow sandy and stony reefs in Sweden and Denmark to the depths of the Norwegian trench.

The Northern limit of the Kattegat [A line joining Skagen (The Skaw, North Point of Denmark) and Paternosterskären (57°54′N 11°27′E / 57.900°N 11.450°E / 57.900; 11.450) and thence Northeastward through the shoals to Tjörn Island].Older names for the combined Skagerrak and Kattegat were the Norwegian Sea or Jutland Sea; the latter appears in the Knýtlinga saga.

In 1862, a short cut, the Thyborøn Channel at the Limfjord was constructed in Denmark through Skagerrak from the North Sea by going directly to the Kattegat.

In the Second World War, the importance of controlling this waterway, the only sea access to the Baltic, was the motive for the German invasions of Denmark and Norway as well as the construction of the northern parts of the Atlantic Wall.

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.

The benthic species include Coryphaenoides rupestris, Argentina silus, Etmopterus spinax, Chimaera monstrosa and Glyptocephalus cynoglossus.

These rare habitats are mostly known from the Danish waters of Skagerrak west of Hirtshals, but more might be discovered in future surveys.

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 and ocean acidification are expected to have increasing impacts on the Skagerrak ecosystem in the future.

[1] Skagerrak and the North Sea receives considerable inputs of hazardous material and radioactive substances.

[13] There are several marine protections in Skagerrak, including: Skaagerak is the setting of the popular television show Badehotellet from Denmark.