You will not stay alone. The Berlin Müggelsee Open Water community is already waiting.

Open-water swimmers based around Müggelsee in the east of the city. Long-distance swim training, boat-safety coordination, and a strong Köpenick/Lichtenberg local base.
Group vibe
Low-key, endurance-focused, tight local group.
Example members. Real archetypes drawn from the people who already meet up here.
From Dresden
Long-distance swimmer, trains here weekly
From Istanbul
New to the east side, found this lake by accident
From Rostock
Local, knows every safe entry point
From Buenos Aires
Weekend swimmer, brings his dog
One number to sign up. Your group is already waiting on the other side.
Join Müggelsee Open Water