Дунав, also known as the Danube, is the second-longest river in Europe, flowing for about 2,860 kilometers. It originates in the Black Forest of Germany and travels through ten countries, including Austria, Hungary, and Romania, before emptying into the Black Sea. The river plays a crucial role in European trade and transportation. The Дунав is home to diverse ecosystems and numerous species of fish and birds. It supports various habitats, including wetlands and floodplains, making it an important area for biodiversity. The river also has cultural significance, with many cities, such as Vienna and Budapest, located along its banks.