Mälaren historically referred to as Lake Malar in English, is the third-largest freshwater lake in Sweden (after Vänern and Vättern). Its area is 1,140 km2 and its greatest depth is 64 m. Mälaren spans 120 kilometers from east to west. The lake drains, from south-west to north-east, into the Baltic Sea through its natural outlets Norrström and Söderström (as it flows around Stadsholmen island) and through the artificial Södertälje Canal and Hammarbyleden waterway. The easternmost bay of Mälaren, in central Stockholm, is called Riddarfjärden. The lake is located in Svealand and bounded by the provinces of Uppland, Södermanland and Västmanland. The two largest islands in Mälaren are Selaön (91 km2) and Svartsjölandet (79 km2). Mälaren is low-lying and mostly relatively shallow.
Being a quite narrow and shallow lake, Mälaren has bridge crossings between Eskilstuna and Västerås with two crossings on the western end at Kvicksund and three separate bridges between Strängnäs and Enköping in the central part of the lake.
