The DANUBE is a river that flows through Central and Eastern Europe, and it is the main river of Budapest, Hungary. It is 656 miles long and is the second longest river in Europe after the Volga. The DANUBE is an important source of water for many countries, including Hungary, Austria, Germany, Romania, and Bulgaria. It is also a popular tourist destination, with many people visiting its banks to enjoy the scenery and take part in activities such as fishing, boating, and swimming.