Danube
Classified as an international waterway, it originates in the town of Donaueschingen, in the Black Forest of Germany, at the confluence of the rivers Brigach and Breg. The Danube then flows southeast for about , passing through four capital cities (Vienna, Bratislava, Budapest and Belgrade) before emptying into the Black Sea via the Danube Delta in Romania and Ukraine.
Enns (river)
The Enns is a southern tributary of the Danube River, joining northward at Enns, Austria. The Enns River spans , in a flat-J-shape. It flows from its source near the towns of Gasthofalm and Flachau, generally eastward through Radstadt, Schladming, and Liezen, then turns north near Hieflau, to flow past Weyer and Ternberg through Steyr, and further north to the Danube at Enns ("see map in References").