The environment in the park is unique to Swedish waters. Over 6,000 marine species have been identified, about 200 of them can not to be found elsewhere in Sweden. The Kosterfjord () is deep with relatively low temperature – – and high
salinity (about 35%).
Brachiopod,
sponge and
coral larvae are brought in by currents from the Atlantic. Rare seabirds, such as
Arctic terns and
skuas, along with a large population of
harbor seals have their habitat here.
Plaice,
cod and
sea trout breed in the more shallow waters closer to the shore. Professional fishing is allowed although special regulations apply. The waters of the park is significant for the fishing of
northern prawn and
Norwegian lobster. Fishing is not subject to environmental protection, and are instead regulated by fishery laws and an agreement from 2000. == Gallery ==