The Skagerrak strait runs between Norway and the southwest coast of Sweden and the Jutland peninsula of Denmark, connecting the North Sea and the Kattegat strait, which leads to the Baltic Sea.

It is roughly triangular in shape, measuring 240 km in length, and between 80 and 140 km in width. It deepens toward the Norwegian coast, reaching over 700 metres at the Norwegian Trench .

The Skagerrak has a salinity of 30 psu and provides a habitat for approximately 2000 marine species.

In both world wars, the Skagerrak was strategically very important for Germany. One of the biggest sea battles of World War I, the Battle of Jutland, also known as the Battle of the Skagerrak, took place there May 31 to June 1, 1916. The importance of controlling this waterway, the only access to the Baltic, provided the motivation for the German invasion of Denmark and Norway during World War II.