The Danube River is the second largest river in Europe after the Volga River. The Danube River flows 1,780 mi (2,860 km) while the Danube River Basin covers an approximate total area of 310,800 mi2 (805,000 km2). The river rises in the Black Forest Mountains of Germany and flows eastward into the Black Sea. The Danube River is an important international waterway, flowing through or forming a part of the borders of ten countries and through major cities such as Vienna, Bratislava, Budapest, and Belgrade. The river is navigable from the Black Sea to Ulm, Germany, and serves as an important transportation corridor by linking the Black Sea to Western Europe and to the port of Rotterdam via the Rhine-Main-Danube Canal. The Danube Delta plain, located in Romania and the Ukraine, predominately consists of marshes and freshwater lakes. The Danube Delta contains the largest continuous marshland in Europe and forms one of the continent’s most valuable habitats for waterfowl nesting. The Danube Delta is still spreading seaward at a rate of 78 to 98 ft (24 to 30 m) annually.