Lake Mälar / Mälaren

Lake Mälar, Sweden's third largest lake (after Lakes Vänern and Vättern), lies immediately west of Stockholm. 117km/73mi long, it extends through the provinces of Västmanland, Södermanland, Uppsala and Stockholm to the Baltic, with a total area of 1,140sq.km/440sq.mi.

It is irregularly shaped, its shores indented by numerous arms and inlets. Its principal tributary rivers are the Eskilstunaå, Arbogaå, Hedström, Kolbäckså, Svartå, Örsundaå and Fyriså. At one time Lake Mälar was an arm of the Baltic, but since the 12th century, because of a fall in the water level, it has been an inland lake. Since 1943 the lake has been regulated to prevent flooding and to avoid unduly low water levels which would hinder the movement of shipping