* Danube River: The Danube River is the second-longest river in Europe, flowing over 2,857 km (1,775 miles) from its source in the Black Forest mountains of Germany to its delta on the Black Sea. It passes through ten countries in Central and Southeastern Europe, including Austria, Bulgaria, Croatia, Germany, Hungary, Moldova, Romania, Serbia, Slovakia, and Ukraine.
* Rhine River: The Rhine River is the third-longest river in Europe, flowing over 1,233 km (766 miles) from its source in the Swiss Alps to its mouth on the North Sea in the Netherlands. It is a major waterway for transportation and trade, and its valley is home to many historical and cultural landmarks, including the Cologne Cathedral and the Lorelei Rock.
* Dnieper River: The Dnieper River is the fourth-longest river in Europe, flowing over 2,201 km (1,368 miles) from its source in the Valdai Hills in northwestern Russia to its estuary on the Black Sea. It is the main waterway of Ukraine and is also navigable in parts of Belarus and Russia.
* Don River: The Don River is the fifth-longest river in Europe, flowing over 1,870 km (1,162 miles) from its source in the Central Russian Upland to its estuary on the Sea of Azov. It is the main waterway of the Don Basin and is also navigable for shipping.