Berlin Köpenick Marathon Swim
From Openwaterpedia

Matthias Kaßner from Germany
The Berlin Köpenick Marathon Swim is a 30 km marathon swim around Berlin, Germany that starts and finishes on a small beach in a village called Schmöckwitz.
Open Water Swimming
Matthias Kaßner completed the first Berlin Köpenick Marathon Swim in 13 hours 7 minutes on 28 August 2020.