Lake Vselug (Russian: Озеро Вселуг) 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 30.4 square kilometres (11.7 sq mi). Lake Vselug is the second 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 Peno, and Lake Sterzh. Lake Vselug is located downstream of Lake Sterzh and upstream of Lake Peno.