The Baltic Sea was formed 15 000 years ago as the glaciers of the last Ice Age receded. Compared with the world's oceans, it contains very little salt and can freeze over in winter. The ice melts quickly in the spring.
Its eastern spur is the Gulf of Finland, which reaches to St. Petersburg. The northern part is the Gulf of Bothnia, which stretches to within 80 kilometres of the Arctic Circle. Because of its northern latitude, the sun hardly drops below the horizon in summer.
Half of the coastland is forest. The islands are countless, some covered by coniferous trees, some just barren rocks polished by the waves.
The sea separates but unites the nine countries with Baltic coastline. Once it was crossed by Viking longships and then the merchants of the Hanseatic League.
Today its cities are connected by numerous shipping lines and visited in summer by the world's leading cruise lines.
