No bathroom

Caspar and I walked through the forest east of Darmstadt and visited the "Grube Prinz of Hessen". This is a small lake of 6 ha (15 acres), that developed after the surface mining at this spot had ended (1924).
During the warmer days the Grube is heavily used as swimming lake. Obviously a container was put close to the lake with room for some privacy. And also obviously some person(s) had another idea about the purpose.
PS: I am not sure who owned the container; it might have been the German Life Saving Association, a water rescue organisation.