Dniester or Dnestr (ancient Tyras or Danastris; Romanian Nistru; Russian Dniester; Ukrainian Dnister), river, western Ukraine and eastern Moldova, 1,400 km (870 mi) long. The Dniester rises in the Carpathian Mountains, near Drohobych in Ukraine, and flows in a generally southeastern direction, partly along the eastern boundary of Moldova, and empties into the Black Sea, near Odesa (Odessa). The broad estuary of the river comprises several arms that form a marshy lagoon, called the Dnistrovs’kiyy Lyman. The average width of the river is 152 to 229 m (500 to 750 ft); the maximum width is about 427 m (about 1,400 ft). For about 70 days of winter, a large part of the Dniester is frozen.

The Dniester drains an area of about 77,700 sq km (about 30,000 sq mi) and is an important traffic artery for the shipment of agricultural produce, livestock, and goods produced in the Dniester Basin. The major city on the river is Tiraspol.

Before World War II (1939-1945) the Dniester formed part of the boundary between Romania and the Soviet Union. During the war large-scale battles were fought on the banks of the river between the German and Romanian invaders and the Soviet defenders.