About Kosterhavets national park
Many of the rare and unique species live in the depths of Koster’s underwater fjord, the Koster trench. It runs through the national park from north to south and attains a depth of 247 metres. The Koster trench is connected with deep submarine areas in Skagerrak that continue all the way out to the North Atlantic’s continental slopes. From there ocean water with high salinity and low temperatures is conveyed into the Koster fjord. That enables many deep-water fauna to live here in very close proximity to the coast. In all, about 12,000 species can be found in the national park area, which covers about 390 square kilometres.
The first marine national park
Kosterhavet National Park is comprised primarily of water and underwater environments. It is Sweden’s first marine national park and is located in the municipalities of Strömstad and Tanum.
In addition to a large expanse of water, the national park also encompasses parts of Rossö island and a large number of islets and skerries, especially in the archipelago south-west of Koster. South Koster and North Koster are not included in the national park, except for a couple of areas on South Koster. The profuse nature of the Koster islands has long been protected as a nature reserve. The same is true of the adjoining nature reserves on the islands of Saltö and Nord Långö .
Next door to Kosterhavet National Park is the Norwegian sister park, Ytre Hvaler. Together these two national parks form a large and valuable marine area with strong environmental protection.