Valdai Lake () is a lake in the middle of the Valdai Hills in Novgorod Oblast, Russia. The area of the lake (without islands) is 19.7 km². The average depth of the Valdai Lake is 12 (the deepest point is 60 m). The lake freezes up in early December and stays icebound until early May. The town of is located on the shores of the Valdai Lake. One of the lake's islands is the place of the .