Tvertsa

The Tvertsa () is a river in Vyshnevolotsky, Spirovsky, Torzhoksky, and Kalininsky Districts, as well as in the cities of Torzhok and Tver in Tver Oblast, Russia, a left tributary of the Volga. It is long, and the area of its basin . The principal tributaries of the Tvertsa are the Malaya Tigma (left), the Shchegrinka (right), the Osuga (right), the Logovyazh (left), and the Kava (left).

The Starotveretsky Canal, which is long and a part of the Vyshny Volochyok Waterway, is considered the Tvertsa's riverhead, which connects the river with the Vyshny Volochyok Reservoir. The latter drains up to 80 percent of its water from the river Tsna into the Tvertsa. The Tvertsa flows south, crosses the western part of Spirovsky District, and south of Torzhok turns east. There, the river enters Kalininsky District and flows towards the city of Tver. In the northern outskirts of the city, the Tvertsa turns south. Its mouth is located in the city center of Tver. The Tvertsa River freezes up in November through early January and stays under the ice until late March or April.