English: Sestra is a river in the European part of Russia, in the Moscow and Tver regions, the left tributary of the river. Dubna (Volga basin).

It originates among the hills of the Klinsko-Dmitrovskaya ridge not far from the sources of the Klyazma River. It flows into the Dubna River 11 km from its mouth. The length of the river is 138 km, the basin area is 2680 km2 - the largest tributary of the Dubna in terms of basin area and length . All tributaries of the Sestra belong to small rivers and streams, the largest of which are: the right ones - Yakhroma (54 km, 988 km2) and Lutosnya (55 km, 364 km2); the left ones are Krutets (23 km, 166 km2), Yamuga (24 km, 283 km2) and Berezovka (25 km, 86.5 km2). Several ponds and reservoirs have been built on the river - Lake Senezh, ponds of the Senezh fishery, the Klin reservoir and others. In the lower reaches, the Sestra crosses the Moscow Canal; a 40-meter concrete tunnel has been built to pass water, passing under the canal perpendicular to it.

In 1850, the Catherine Canal was opened, connecting the Moscow and Volga rivers, partly the canal passed along the Sestra River (32 km), and partly along the derivation canal along the Sestra River (66.7 km). Part of the Sestra's channel was straightened, 20 wooden and stone sluices were built on it. Unable to withstand competition with the Nikolaev railway from St. Petersburg to Moscow, which opened in 1851, the canal was closed in 1860, the locks were dismantled.

The Sestra is a flat river with a winding channel, there are straightened sections. Large stones, small rifts, remnants of destroyed dams and piles of destroyed bridges are found in the riverbed. The current speed reaches 0.4 m / s. The channel width in the upper reaches is 10–15 m, the depth is up to 1 m, below the dam of the Klin reservoir, the width is 20–30 m, the depth is up to 1.5 m. In the lower reaches, the width reaches 50 m, the depth is up to 3 m.