Mälaren is the largest lake in Sweden, after lakes Vänern and Vättern. It drains, from west to east, into the Baltic Sea at Stockholm. The easternmost bay of Mälaren, in central Stockholm, is called Riddarfjärden. The lake is located in Svealand and bounded by the Provinces of Uplandia, Sudermannia, Nericia, and Westmannia.
See also: Lakes in Sweden, Geography of Stockholm