Drava River, German Drau, a major right-bank tributary of the Danube River, in south-central Europe. It rises in the Carnic Alps near Dobbiaco (Toblach), Italy, and flows eastward through the Austrian Bundesländer (federal states) of Tirol and Kärnten, where it forms the Drautal, the longest longitudinal valley of the Alps. From there it flows southeastward through Slovenia. Near Legrad, Croatia, it is joined by the Mura (Mur) River and forms part of the Croatian-Hungarian border.
The originally swift course of the Drava has been harnessed by hydroelectric power plants in Austria, Slovenia, and Croatia. It is navigable only by small boats in its upper reaches and by larger craft downstream from Donji Miholjac, Croatia. The Drava valley was the chief passage through which invaders from the east, such as the Huns and Slavs, penetrated the Alpine countries. The main towns of the Drava and its affluents are Klagenfurt and Graz in Austria, Maribor and Ptuj in Slovenia, and Varaždin and Osijek in Croatia.