Gulf of Bothnia (Perämeri)

Bothnian Bay National Park, Perämeren kansallispuisto, was established in 1991 at the northern end of the Baltic Sea, off the coasts of Lapland and North Ostrobothnia. It protects 157 km² of sea and some thirty islands and islets, most of them uninhabited, across the municipalities of Kemi, Tornio and Simo.

The feature that defines this sea is twofold. First, salinity: the Bothnian Bay receives the inflow of great rivers and is very far from the connection with the Atlantic, so that its waters are barely brackish, almost fresh, and hold an unusual mixture of marine and freshwater species. Second, isostatic uplift: the ground is still rebounding after the disappearance of the weight of the ice sheet, and it rises at a rate of almost a centimetre a year, one of the fastest on the planet. The result is an archipelago in permanent formation, where shoals become islets and islets become islands, and where vegetation continuously colonises new ground.

That dynamic has generated a specialised coastal flora, with several species endemic to the Bothnian Bay adapted to the emerging shingle beaches. The islands are a breeding area for seabirds and waterbirds, and the sea is home to the Baltic ringed seal, a threatened subspecies isolated since the last glaciation. The traditional activity of the area has been coastal fishing, and some islands preserve fishermen's huts and stores.