The Christlessee is a mountain lake in the heart of the Trettach valley, at an altitude of more than 900 meters. There are several karst springs at the bottom of the lake, which ensure that it never freezes – even with minus 30 degrees - over in winter, as this spring water has a temperature of four to six degrees in both summer and winter. Just to the south of the lake are powerful springs, which feed clear water into the lake, giving it good drinking water quality.