Danube River

The Danube (In German: Donau, in Hungarian Duna, in Slovenian: Donava, in Croatian: Dunav, ancient Greek: Istros) is Europe's second longest river (after the Volga) and the longest river in the European Union. It originates in the Black Forest in Germany and flows through (or forms a part of a border of) Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine.