Läänemeri

Läänemeri is the Estonian name for the Baltic Sea, a large brackish marginal sea of the Atlantic Ocean located in Northern Europe. It is bordered by Sweden and Denmark to the west, Finland to the north, and Estonia, Latvia, Lithuania, Poland and Germany along its eastern and southern shores, with Russia’s Kaliningrad Oblast on the southeastern edge. The Baltic Sea is connected to the North Sea through the Danish straits—the Sound, the Great and the Little Belts—and includes major sub-basins such as the Gulf of Bothnia and the Gulf of Finland.

Geographically, the Baltic Sea covers about 377,000 square kilometers. It is relatively shallow, with an average depth around 55 meters and a maximum depth near Landsort Deep of about 459 meters. Water exchange with the open ocean is limited, giving the sea its characteristic brackish water and low salinity compared with open seas. The surface sea ice can form in winter in the northern parts.

Geologically, the sea was largely formed after the last glaciation, as glaciers retreated and the land rebounded (isostatic rebound). The modern basin comprises the Baltic proper, the Gulf of Bothnia, the Gulf of Finland and connected basins separated by straits and shallow channels.

Ecologically, the brackish conditions support a relatively unique flora and fauna, including species such as herring, sprat and cod adapted to low salinity. The basin faces eutrophication and episodic hypoxic zones in deeper areas due to nutrient runoff, prompting ongoing protection and restoration efforts.

Humans rely on the Baltic Sea for shipping, ports and fisheries. It is governed by international cooperation, notably through HELCOM and regional protection plans aimed at reducing pollution and restoring ecosystem health.