The Seddinsee is a lake situated in the south-eastern outskirts of Berlin, the capital city of Germany. The lake is aligned south-west to north-east, with its south-western end adjacent to the Berlin suburb of Schmöckwitz. Here the Seddinsee meets the Zeuthener See and Langer See, two lakes which form part of the course of the River Dahme. The Seddinsee is navigable. Besides its natural connection to the River Dahme, the Oder-Spree Canal enters the lake on its eastern shore, whilst the Gosen Canal links the lake's northern end to the Dämeritzsee.