The River Danube is the second-longest river in Europe, flowing approximately 2,860 kilometers (1,780 miles) through ten countries. It originates in the Black Forest of Germany and travels southeast, eventually emptying into the Black Sea. The river passes through major cities such as Vienna, Budapest, and Belgrade, making it an important waterway for trade and transportation. The Danube is known for its diverse ecosystems and rich cultural history. It supports various wildlife and is a vital habitat for many species. Additionally, the river has been a significant cultural and historical landmark, influencing the development of the regions it traverses.