Sea between the Finnish Åland islands and the Swedish mainland, part of the Baltic Sea
The Åland Sea (or the Sea of Åland; Swedish: Ålands hav, Finnish: Ahvenanmeri) is a waterway in the southern Gulf of Bothnia, between Åland and Sweden. It connects the Bothnian Sea with the Baltic Sea proper. The western part of the basin is in Swedish territorial waters while the eastern part is in Finnish territorial waters. The Åland Sea has two sub-basins. The main basin is the Åland Sea proper, also called the northern Åland Sea basin. In the south, there is the smaller Lågskär Deep, also called the Lågskär Basin or the southern Åland Sea basin.
https://en.wikipedia.org/wiki/Sea_of_%C3%85land