Mälaren

Mälaren is a great lake in central Sweden, its many islands and branching waters reaching westward from Stockholm. It was once connected directly to the Baltic, but the gradual rise of the land turned the basin into a freshwater lake during the Middle Ages. Older trading centres such as Birka and Sigtuna stood beside its waters. Stockholm grew at its outlet, where goods moving between lake and sea had to pass, giving the city a commanding place in the region's trade.