Lake Plansee - nearby Reutte - is the second-largest natural lake in Tyrol. The lake is fed by the Spiessbach and Torsäulenbach, as well as by Lake Heiterwang and its runoff is the Archbach river. Lake Plansee is characterised by outstanding water quality of grade A. The water is used for generating electricity.

Lake Plansee is situated at an altitude of 976 m, has a surface of 280 ha and a maximum depth of 78 m.