Dvina or Western Dvina, Ger. Düna, Latvian Daugava, Rus. Zapadnaya Dvina, river, c.635 mi (1,020 km) long, in Russia, Belarus, and Latvia. Rising in the Valdai Hills, it flows S and then generally W past Velizh and through Belarus, past Vitebsk and Polotsk, and through Latvia, past Daugavpils and Riga, into the Gulf of Riga, an arm of the Baltic Sea. It is navigable in its upper course, but, because of rapids and hydroelectric dams, is only partly navigable in its lower course. The Dvina's main port is Riga, and the river is connected by canal with the Berezina and the Dnieper rivers.