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.
List of tributaries of the Danube
The Danube flows through—or forms a part of the borders of—ten countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine; in addition, the drainage basin includes parts of nine more countries: Poland, Switzerland, Italy, Czech Republic, Slovenia, Bosnia and Herzegovina, Montenegro, Republic of Macedonia and Albania.