In summer months the swimming baths close but the civic baths administration (BBB) website gives details of the 20 more more natural lakes for swimming. These vary from more organised with lidos, cafes and changing rooms to hidden away natural wooded enclaves. Most welcomes naturism (FKK in german) and many gay as well as str8 sunbathers and swimmers. This is the way meet Berliners. The BBB website gives details of the water quality, updated daily.