Plön is the district seat of the Plön district in Schleswig-Holstein, Germany, and has about 8,700 inhabitants. It lies right on the shores of Schleswig-Holstein's biggest lake, the Great Plön Lake, as well as on several smaller lakes, touching the town on virtually all sides. The town's landmark is Plön Castle, a chateau built in the 17th century on a hill overlooking the town.

The Großer Plöner See or Lake Plön is the largest lake (30 km2) in Schleswig-Holstein, Germany. It is located near the town of Plön. Its main tributary, as well as its main outflow, is the River Schwentine.