Lake Bohinj is located in a glacially formed lake basin and holds almost 100 million cubic metres of water. According to an old Bohinj joke, only one bucket if the bucket is big enough. The lake basin, which descends steeply, is not indented and is almost without shallows. The lake warms up to 24°C at the surface in summer and often freezes in winter. Water levels rise by more than 3 m during heavy rainfall.