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.“)
Hydrology of Hungary
The Danube is the second longest river in Europe, after the Volga. Its upper flow is outside of Hungary, but its middle section starts at Devín, close to the Hungarian border. This section of the river stretches until the Iron Gate, between Serbia and Romania. The lower section of the river crosses the Romanian Plain and flows into the Black Sea through a delta. The Hungarian section of the river is long, from which forms the border between Hungary and Slovakia, from Rusovce to the mouth of the Ipeľ ().