The Grunewaldsee is a lake located in western Bezirk Charlottenburg-Wilmersdorf in Berlin within the Grunewald forest. It has a surface of c. 175,000 m2. The Jagdschloss Grunewald hunting lodge is located on the south bank of the lake.
Bathing has been officially prohibited for humans since 2004.
Wikipedia https://en.wikipedia.org/wiki/Grunewaldsee
Coordinates 52°28'12.128" N 13°15'44.632" E