Cerkniško jezero (Cerknica Lake) is an intermittent lake and covers 26 km2  - when fully watered even up to 38 km2. It is 10 km long and 5 km wide, which makes it the largest lake in Slovenia.

Cerknica Lake - a Karst intermittent (disappearing) lake is also very famous and actually a unique site. It is a lake in which for a half of the year one can fish and, in winter, skate on the frozen surface. It starts to disappear in spring and leaves behind a polje (field), where farmers cut hay through the summer. The causes of the drying out of this natural curiosity, already famous in classical times, were studied more than three hundred years ago by the natural and social historian, Janez Vajkard Valvasor. His report encouraged great interest; and he was elected a member of the Royal Society in London for his interpretations.

More information: Virtual reality panoramas of the lake through seasons