The Danube is the most important European river and comprises Pan-European transport corridor VII. It is an integral part of the Rhine-Main-Danube system, whose 3505 km of waterways connect the Atlantic to the Black Sea, Western Europe to Eastern Europe.
The Danube has a long history as an important international waterway. For a long time it formed the northeastern boundary of the Roman Empire.
Today it flows through or forms the border of ten countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine. The Danube originates as the Breg and Brigach rivers which rise in the Black Forest mountains, flowing into the Black Sea in Romania. With a 2783 km course it is the second-longest European river (after the 3692 km-long Volga), and the 27th largest in the world, the 32nd largest counting its basin. The Danube forms a delta 5,500 km2 in area where it flows into the Black Sea, with three major distributaries.
Along its 588 km course through Serbia, the Danube extends from the meeting of the Serbian, Hungarian and Croatian borders to its confluence with the Timok where the borders of Serbia, Bulgaria and Romania meet. It passes through the picturesque Vojvodina flatlands and the national parks of the Fruška Gora and Đerdap. Besides its natural wealth, there are many sites of cultural and historical value spread out along its banks. Its main tributaries in Serbia are the rivers Tisa, Sava, Tamiš, Morava, Nera and Timok.
The Danube is the most popular river in the world for river cruises, and is a major asset of Serbia’s tourism industry, with Serbia's two largest urban centres – Belgrade and Novi Sad – located on its banks.
The Dunav-Tisa-Dunav canal is a unified system of canals built to defend against flooding, for irrigation of land, for navigation, for tourism and for hunting and fishing. The canal system extends across some 12,700 km² between the Danube and the Tisa rivers in the Bačka and Banat districts of Vojvodine. The total length of the canals is 929 km, of which 664 km are navigable. The canal system includes 14 docks where cargo can be loaded and unloaded.