Ostufer Kalksee Alt-Rudersdorf

A beautiful clear lake with some bays (but at your own risk). A very nice hiking trail leads along Kalkseeufer.

It stretches 2km in length and is up to 10m deep. There are many swimming areas and there is a lot of boat traffic on the water.

The Kalksee is a body of water in the south of Rüdersdorf in the Märkisch-Oderland district, east of Berlin. The name is derived from the proximity of the Rüdersdorf limestone deposit, which is unique in the state of Brandenburg.
The Kalksee is used for swimming, water sports and as a transport route. The lake borders Woltersdorf to the south and west and Rüdersdorf to the north and east.
Despite its name, the Kalksee is a clean swimming lake and has been awarded the blue EU flag for clear waters since around 2002.
The Kalksee is connected to the south with the adjacent Flakensee through the Woltersdorf lock at the southern end of the Kalkfließ. To the north a connection leads through the Stolpgraben and the Hohlen See into the Strausberger Mühlenfließ, which leads to the Langerhanskanal and the Stienitzsee.

Source: de.wikipedia.org/wiki/Kalksee_(Rüdersdorf)