Drava, also Drave (German Drau), river in Europe, an important affluent of the Danube River. The Drava rises south of the Hohe Tauern Alps near the Italian town of Dobbiaco in the province of Trentino and flows through the scenic Pustertal, the longest longitudinal valley of the Alps, toward Lienz, Austria, where it is joined by the Isel River. In Austria the river is known as the Drau. The river then flows east through Maribor, Slovenia, traversing the northeastern tip of that country, through the northern tip of Croatia, and is joined by its principal branch, the Mura River, near Csurgó, Hungary. From there, flowing southeast for 145 km (90 mi), the Drava forms most of the boundary between Hungary and Croatia, to a point near Osijek, Croatia, before it ends by joining the Danube. In the first part of its 719-km (447-mi) course, the Drava is a mountain torrent. From Villach, Austria, to Barcs, Hungary, it is navigable by raft only; from Barcs to its mouth, a distance of 105 km (65 mi), it is navigable by small vessels. At its mouth the Drava is 322 m (1,055 ft) wide.