Greifensee is a lake in the canton of Zürich in Switzerland.
Greifensee is located 11 km to the east of the city of Zürich, separated by the Pfannenstiel from Lake Zurich. As the second largest lake in the canton of Zürich (Lake Zurich being the largest), it is about 6 km long and 1.6 km at the widest point, with a maximum depth of 32 m. The Aabach (Greifensee) (or just Aa) is the main supplying river, while its outlet is the Glatt. On its southeastern end the Mönchaltorfer Aa (or just Aa) enters the Greifensee.
