Vienna's River is the DANUBE, a 6 letter river that flows through Central and Eastern Europe. It is the second longest river in Europe after the Volga and is the only major European river that flows from west to east. The DANUBE originates in Germany and passes through Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine before emptying into the Black Sea. It is an important source of water for many countries and is also used for transportation, irrigation and hydroelectric power generation.