Lake Peno (Russian: Озеро Пено) is a lake in Penovsky District of Tver Oblast, Russia. The Volga River flows through the lake in its upper course. The area of the lake is 16.7 square kilometres (6.4 sq mi). Lake Vselug is the third one of four big lakes which make together and which constitute the only remaining large natural lake system on the Volga. The other three lakes of the system are Lake Volgo, Lake Vselug, and Lake Sterzh. Lake Peno is located downstream of Lake Vselug and upstream of Lake Volgo.