Froschloch

In the location's words:

The Froschloch outdoor pool in Dortmund is a real summer paradise. With its green, idyllic ambience, it invites you to relax and cool off. The natural pool provides refreshing swimming fun. The spacious lawn offers enough space for sunbathing, relaxing and beach volleyball.

https://www.sportwelt-dortmund.de/oeffnungszeiten/