群岛海
The Gulf of Bothnia (; ; , also divided as "Bothnian Bay" + "Bothnian Sea") is the northernmost arm of the Baltic Sea. It is situated between Finland's west coast (Ostrobothnia) and Sweden's east coast (Westrobothnia and North Bothnia). In the south of the gulf lie the Åland Islands, between the Sea of Åland and the Archipelago Sea.