Sterzh - a lake in Ostashkov district of Tver region of Russia, the third largest in the Upper Volga (Verkhnevolzhskie) lakes in the Valdai Hills, the first group of lakes through which the upper reaches of the Volga River. "Sterzh" means "quiet lake".
Length - 12 km, width - 1.5 km, average depth - 5 m, maximum - 8 m, area is about 18 km ².
The shores of the lake, which is a typical Seligersky reach relatively high, the bottom and the banks are composed of sand and pebbles.
Previously, the lake was navigable, it was held by passenger line Peno - Shirkov Churchyard - Kokovkina, length of the line - 60 km, served by steamer "Summer Lightning".