Kosterhavet National Park

- the most species rich sea in Sweden

Kosterhavet National Park was established in 2009. It is the first national park in Sweden which protects marine wildlife. The majority of the almost 39 000 ha of the park is water, less than 900 ha is land. It is one of the largest national parks in Sweden, and stretches from the Norwegian border in the north and south to the waters outside of Grebbestad. The aim of the national park is to conserve the distinctive and species rich marine and archipelago area as well as adjacent land in an essentially unchanged condition.


Species richness
Kosterhavet is the most species-rich marine environment in Sweden with over 6 000 different marine animals and seaweeds. All of the underwater species from the west coast are found here, as well as a large number of species which have their main or only known distribution just here. Many of the rare and unique species are associated with the deep trench in the Koster Fjord. It runs through the national park from north to south and has a maximum depth of 247 metres. The trench continues all the way out to the North Atlantic continental shelf, from where oceanic water with a high salt content and low temperature comes into the Koster Fjord. This makes it possible for many deep water animals to live here, very close to the coast.

Protection beyond borders
The unique underwater wildlife of Kosterhavet continues north across the border into the Norwegian national park Ytre Hvaler. Here, there are several large coral reefs, including Tisler Reef which is the largest coldwater reef in the Atlantic this close to the shore. Together, the both parks create a protected marine environment of almost 800 square kilometres.

Geology of the archipelago
The islands of the national park rise out of the sea like barren rolls and elongated loaves of bread. West of the Koster Fjord they are made of ancient forms of gneiss, in contrast to the coast and inner archipelago where the much younger bohus granite dominates. On the exposed bedrock it is obvious to see how the rocks from different epochs have been kneaded together during the long geological history of the area. Giant hollows and impressive shingle beaches are seen in several places.

On land – national park and nature reserve
As well as the large marine environment which makes up the national park, parts of the island of Rossö and a large number of islands and islets, especially in the archipelago southwest of Koster are also included. Syd- and Nordkoster are not included in the national park, apart from a couple of small areas on Sydkoster. The rich wildlife of the Koster islands has long been protected as a Nature Reserve and will continue to be so. The island of Ramsö is not included in the park.

Places to visit
There is always something to do at Kosterhavet; swimming in the summer, the stillness of the spring and autumn and the roaring storms of the winter. Here are a few gems:

Resö harbour – living fishing village

Rossö harbour – historical shellfish centre

Kockholmen – hiking and bird watching

Tjärnö – marine research station and aquarium

Saltö – coastal pine woodland and rocky beaches

Långevik on Sydkoster – excellent snorkling waters

Brevik on Sydkoster – coastal meadows and heathlands

Ursholmen – seals, geology and wide horizons

How to get to Kosterhavet
Kosterhavet National Park is located in northern Bohuslän and can be reached from several of the landscape's coastal towns. Take the train along the Bohusbana or follow the E6 motorway north from Göteborg towards the Norwegian border. Koster ferries leave from Strömstad throughout the year. On their way to the Koster Islands pass through the national park. From the islands of Resö, Rossö and Tjärnö there are lovely views over Kosterhavet and you can also find information there.

Read more on the Kosterhavet National Park website.

Title by Photographer