Baden-Württemberg The Mathisleweiher is a large bog lake, under 2 hectares in area, in the Black Forest in southern Germany.

It lies in the High Black Forest between Feldberg in the west and the Titisee in the east on the territory of Hinterzarten at about 999 m above NN southwest of the village in the Eschengrundmoos Nature Reserve.

The stream rises on the eastern slopes of the Ramselehöhe (1,112 m above NN[LUBW 3]) at about 1,055 m above NN,[LUBW 4] picks up the Eschengrundmoosbach from the right from the protected bog and runs for less than a kilometre before entering the lake.

A path runs from the village passing close to the lake and a spur branches off to the east shore.

Together with the Mathislehof, Mathislemühle and Mathislewald the pond belongs to the Müller-Fahnenberg Foundation of the University of Freiburg.