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.
Lauter (Danube)
The Lauter, also: "Große Lauter", is a small river of the Swabian Alb, Baden-Württemberg, Germany. Its Karst spring is inside the walls of the former nunnery at "Offenhausen", a small settlement near Gomadingen. The river discharges into the Danube after 42 km. The river has a long geological history since late Miocene. Although the Swabian Alb is heavily karstified, this river's water runs aboveground all the way.