The source of the Danube River is located in the Black Forest in Germany, while the river's mouth is located on the Black Sea coast, stretching across parts of both Romania and Ukraine. The river is approximately 1,770 miles in length and flows through nine different countries.
The Danube is Europe's second-longest river after the Volga. It passes through a number of major cities, including Vienna, Budapest and Bucharest. The river's drainage basin measures around 315,000 square miles and includes more than 300 separate tributaries.
The Danube is navigable by river ships from its delta all the way to Kelheim in Bavaria. In 2007, more than 50 million metric tons of freight were transported down its course.