The Leopoldsteinersee is a mountain lake in Styria, in the east of Austria, about 4 kilometres (2.5 mi) northwest of the city of Eisenerz.

The Leopoldsteinersee is situated at 628 metres (2,060 ft) above sea level at the foot of the Seemauer in the western Hochschwab range.

The river Seebach feeds the lake, but it is mainly fed by underground springs.

[1] The lake is surrounded by rugged mountains with mixed or coniferous forests.

To buy his freedom he showed his captors the iron deposits at Erzberg.