The final section of the Jog, Kayaking the entire length of the River Danube, from the Black Forest to the Black Sea. The second longest river in Europe, The Danube was once a long-standing frontier of the Roman Empire, and today flows through 10 nations. Originating in Germany, the Danube flows southeast for 2,860 km (1,780 mi), passing through or touching the border of Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine before emptying into the Black Sea. Its drainage basin extends into nine more nations.