Source of the Danube
As early as 1847 the following definition can already be found in the "Universallexikon des Großherzogtums Baden" (Universal Lexicon of the Grand Duchy of Baden): “Danube, the biggest river of Germany, rises at the Martinskapelle in a wild and lonely area of the Black Forest, is called Brege at its origin and forms the river Danube in Donaueschingen where it is unified with the Brigach." (German original: „Donau, der größte Fluß Deutschlands, entspringt bei der Martinskapelle in einer wilden und einsamen Gegend des Schwarzwaldes, heißt am Anfang Brege… und bildet erst in Donaueschingen, wo sie sich mit der Brigach vereinigt, die Donau.“)
Serbia
Almost all of Serbia's rivers drain to the Black Sea, by way of the Danube river. The Danube, the second largest European river, passes through Serbia with 588 kilometers (21% of its overall length) and represents the largest source of fresh water. It is joined by its biggest tributaries, the Great Morava (longest river entirely in Serbia with 493 km of length), Sava and Tisza rivers. One notable exception is the Pčinja which flows into the Aegean. Drina river forms the natural border between Bosnia and Herzegovina and Serbia, and represents the main kayaking and rafting attraction in both countries.