Socialist Federal Republic of Yugoslavia
Regarding rivers, the Danube was navigable throughout its entire course in Yugoslavia, linking the ports of Belgrade, Novi Sad, and Vukovar with Central Europe and the Black sea. Long stretches of rivers Sava, Drava and Tisza were also navigable.
Geography of Austria
The Danube has its source near Donaueschingen in southwestern Germany and flows through Austria before emptying into the Black Sea. It is the only major European river that flows eastwards, and its importance as an inland waterway has been enhanced by the completion in 1992 of the Rhine-Main-Danube Canal in Bavaria, which connects the Rhine and Main rivers with the Danube and makes barge traffic from the North Sea to the Black Sea possible.