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.
Danube–Black Sea Canal
The course of the canal follows mostly the course of the former Carasu River, originally a tributary of the Danube. Therefore, hydrographically it also has the function of conveying the runoff from a drainage basin to the Black Sea.