1. INN RIVER
The Inn River is the first of the Danubes main tributaries. It starts in Switzerland and then travels in Austria, Germany and it flows in to the Danube on the German-Austrian border.
2. DRAVA RIVER
The second tributary is the Drava River. It springs on the northern border of Italy. It then travels through Austria, Slovenia, Croatia and on Hungarys border. It then flows into the Danube.
3. TISZA RIVER
The third tributary is the Tisza. This river starts in Ukraine and moves on the northern border of Romania. It continues its journey in Hungary and finally in Yugoslavia. The length of this river is 966 km and the area of the basin is 157,220 sq km.
4. SAVA RIVER
The fourth of the Danubes main tributary is the Sava River. It springs on the northern border of Bosnia-Herzegovina and it flows through Yugoslavia and finally meets the Danubes waters. The length of this river is 940 km and its basin area is 95,719 sq km.