Lake Toplitz

Lake Toplitz is a lake situated in a dense mountain forest high up in the Austrian Alps, 98 km from Salzburg in western Austria. It is surrounded by cliffs and forests in the Salzkammergut lake district, within the Totes Gebirge. The Toplitzsee water contains no oxygen below a depth of 20 m. Fish can survive only in the top 18 m, as the water below 20 m is salty, although bacteria and worms that can live without oxygen have been found below 20 m.

In 1943 and 1944, the shore of Lake Toplitz served as a Nazi naval testing station. Using copper diaphragms, scientists experimented with different explosives, detonating up to 4,000 kg charges at various depths. Over £100 million of counterfeit pound sterling notes were claimed to have been dumped in the lake after Operation Bernhard, which was never fully put into action.