In the Bay of Bothnia there is fast ice in the archipelagos, up to 60 cm thick in the north and up to 50 cm thick in the south. At sea in the north, there is mostly 30–60 cm thick, very close, partly ridged and rafted ice that is difficult to force at places. At sea in the south there is 10–35 cm thick very close ice. In the Quark there is up to 50 cm thick fast ice at the coasts and at sea there is mostly 10–35 cm thick, close to very close ice. At the coasts of the Sea of Bothnia there is fast ice, up to 55 cm thick in the east and up to 30 cm thick in the west. At sea in the north there is mostly close, 5–35 cm thick ice. In the southern part there is very open to close drift ice off the coast in the west and a narrow band brash ice of varying con-centration in the east. Level ice or fast ice covers large parts of the Archipelago Sea and thin very open drift ice is present in the Åland Sea. There is up to 55 cm thick fast ice at the eastern and northern coast of the Gulf of Finland. In the northern part west of Gogland there is mostly very close, 5–25 cm thick drift ice and in the east is 10–35 cm thick, very close ice. In the Gulf of Riga there is up to 35 cm thick fast ice in the northeast and close to very close ice is present off the coast in the north. Else up to 30 cm thick fast ice or thin level ice is present in the Mälaren, Vänern, Norwegian fjords and along the Swedish coast north of Kalmar.
Bundesamt für Seeschifffahrt und Hydrographie (BSH)