Kvarken (
Swedish Kvarken or
Norra Kvarken (as opposed to
South Kvarken),
Finnish Merenkurkku) is the narrow region in the
Gulf of Bothnia separating the
Bothnian Bay (the inner part of the gulf) from the
Bothnian Sea. The distance from Swedish mainland to Finnish mainland is around 80 km while the distance between the outmost islands is only 25 km. The water depth in the Kvarken region is only around 25 meters. The region also has an unusual rate of
land rising at about 1 cm a year.