The E1620 2 part of the Donau is a large and important river in Central and Eastern Europe that originates within the Black Forest Mountains of Germany. It empties into the Black Sea and is the second-longest river in the European Union, trailing only the longest river, the Danube. Along its course, the river passes through 10 countries and has many important tributaries, including the Elbe, Oder, Vltava, and Sava rivers. Its drainage basin covers an area of 801,463 km², making it the second largest in Central and Eastern Europe after the Volga basin. The river is an important source of food, transport, and energy for millions of people. In addition, it is a major contributor to the region's economy, providing irrigation and hydropower to upstream settlements. The river is also an important habitat for a variety of fish and wildlife species, making it a popular destination for recreational activities such as fishing and canoeing.