A maximum level is reached by mid July but may be topped in August even after previous falling due to summer rain.

The lake is in a huge forest that was allowed to remain on the agriculturally useless debris area of the biggest prehistoric rockslide in the Alps and can only be reached by a footpath (wheelchair accessible), possibly using Caumasee-Lift, a funicular built in 1939, refurbished in 1988 on its original tracks (running May to October only).

This lake dries out completely in autumn and remains empty until being filled by a small river of just about 800m in length, covering some 100 meters difference in altitude.

Its origin is another lake, Lag Prau Pulté, which is fed by underground water only in spring, disappearing in autumn and staying dry all winter.

A fourth lake, Crestasee, is also fed by underground water but retains a constant level all year.