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.
Ybbs
Its source is located on the Zellerrain Pass near Mariazell. The river is called the "Weiße Ois" in the beginning, then onwards from the border between Lower Austria and Styria to Lunz am See it is called the "Ois", and from there until it meets the Danube at "Ybbs an der Donau", it is called "the Ybbs".