Baltic Sea

Baltic Sea, enclosed sea, northern Europe, bounded by Sweden, Finland, Estonia, Latvia, Lithuania, Russia, Poland, and Germany. It is connected with the North Sea by a series of winding channels: the Öresund (Øresund), Storebælt (Great Belt), Lillebælt, Kattegat, and Skagerrak. From the peninsula of Denmark, considered the Baltic’s limit, the sea extends east to longitude 30° east and north to about latitude 66° north. The greatest length of the Baltic, from Lübeck, Germany, to Haparanda, Sweden, is 1,500 km (930 mi); the breadth varies from 690 km (430 mi), between Stockholm and Saint Petersburg, to less than 80 km (50 mi) at the southern extremity. The Baltic covers an area of 422,000 sq km (163,000 sq mi).

The northern extension consists of two large gulfs: the Gulf of Bothnia, between Finland and Sweden, and the Gulf of Finland, between Finland and Estonia. The Gulf of Rīga is a prominent feature of the Baltic’s Estonian and Latvian coasts. On the coasts of Poland and Germany are smaller indentations, including the Gulf of Gdańsk (formerly Danzig) and the Bay of Szczecin (Stettin), both in Poland, and the German bays of Lübeck and Kiel. The principal islands are Rügen Island (Germany), Bornholm Island and the Danish groups (Denmark), Gotland and Öland islands (Sweden), Saaremaa (Ösel) and Hiiumaa (Dagö) islands (Estonia), and the Åland Islands (Finland).

The Baltic receives the drainage from a large part of northern Europe, including Estonia, Latvia, Lithuania, northern Germany, and nearly all of Sweden. As a result of this drainage and of the restricted channel to the North Sea, the surface water of the Baltic contains relatively little salt—only a third as much salt as the Atlantic Ocean—and the salinity shows a tendency to decrease toward the west and north. Surface currents of low salinity flow constantly from the Baltic to the North Sea, while deeper currents, with a larger salt content, flow in the opposite direction. Tidal action is apparent only in the southern part of the Baltic.

Storms are frequent in the Baltic Sea and often cause severe damage to ships. Easterly winds are particularly dangerous because they create huge waves. Navigation in the northern part of the Baltic is suspended during the winter and early spring because of ice.

The Baltic is of great commercial importance to northern Europe. The most important ports are Copenhagen in Denmark; Kiel and Lübeck in Germany; Szczecin, Gdańsk, and Gdynia in Poland; Kaliningrad, Saint Petersburg, and Kronshtadt in Russia; Rīga in Latvia; Tallinn in Estonia; Helsinki and Åbo (Turku) in Finland; and Stockholm, Karlskrona, and Malmö in Sweden. The Baltic is connected with the North Sea by the channels mentioned above and by the Nord-Ostsee-Kanal (the Kiel or Kaiser Wilhelm Canal), with the White Sea by the White Sea-Baltic Canal, and with the Volga River by the Volga-Baltic Waterway. The Baltic is connected with the Caspian and Black seas by the Volga-Baltic Waterway and the Volga-Don Canal.