The Selenter See is the second-largest lake in the North German state of Schleswig-Holstein, after the Großer Plöner See. It lies at an elevation of 37 m above sea level and has an area of 22.4 km². The Selenter See, which lies near the village of Selent in the district of Plön, is 34 m deep. The lake drains into the Baltic Sea through the Hohenfelder Mühlenau, only 10 km long, to the north and by the Salzau to the northwest.