The Danube (Latin name Hister) is the second-longest river in Europe (the Volga is the longest). It is the longest river of the European Union.

The river is 2,860 km (1,777 mi) long. Brigach and Breg join in Donaueschingen (near the Black Forest) to "make" the Danube. The Danube flows through or makes part of the border of 10 countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine. The river ends in the Black Sea through the Danube Delta.