Zwenkauer See, Recreational reservoir in Leipzig, Germany

Zwenkauer See is a reservoir near Leipzig that covers roughly 970 hectares with about 22 kilometers of shoreline. The water reaches depths of around 49 meters in some areas, with multiple sections designed for swimming, sailing, and other water activities.

The lake formed from an old lignite mining pit that operated until 1999, transforming the landscape once extraction ended. After mining stopped, the pit was filled with water and converted into a recreation area for the region.

The lake's name comes from the town of Zwenkau, whose former open-cast pit it fills; the villages of Bösdorf and Eythra were cleared and dug away for the mine between 1980 and 1987, and an information board on the southern shore recalls Eythra's history. Since 2011 a new borough has grown at Kap Zwenkau around a sailing and water-sports harbour, with terraced residential and mixed-use rows.

The lake can be accessed from multiple points along the shore, with parking available near the harbor area and regular bus connections to the KAP Zwenkau station. The summer months offer the best visiting conditions when water temperatures are comfortable and facilities are fully open.

The lake's water arrives through a 63-kilometre ring pipeline linking the Neuseenland lakes with the still-active Vereinigtes Schleenhain and Profen open-cast mines, where it accumulates as drainage water. About 45 cubic metres per minute were fed in, raising the level roughly two centimetres a day at the start of flooding.