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.
European watershed
The divide continues northwards along the Albula Alps to Julier Pass, Albula Pass and Flüela Pass south of Davos between the catchment area of the Rhine, which empties into the North Sea via the Netherlands, and the Danube, which flows eastward emptying into the Black Sea. It enters Austria at Piz Buin in the Silvretta Alps running along the Arlberg massif and forming the border between the states of Tyrol and Vorarlberg. It reaches Bavaria, Germany via the crest of the Allgäu Alps and leaves the High Alps at the Adelegg range near Kempten.