Tvertsa (Russian: Тверца) is a river in the Tver Oblast in Russia, a left tributary of the Volga River. The Starotveretsky Canal (2,9 km in length) is considered Tvertsa's riverhead, which connects the river with the Vishnevolotskoye Reservoir. The latter drains up to 80% of its water from the Tsna River into the Tvertsa. The Tvertsa River freezes up in November - early January and stays under the ice until late March - April.
The towns of Torzhok and Vyshny Volochyok are located on the Tvertsa River. The city of Tver is located at its confluece with the Volga.
Coordinates: 57°33′17″N 34°36′12″E / 57.55472°N 34.60333°E