There are three artificial waterways built on the Danube : the Danube-Tisa-Danube Canal ( DTD ) in the Banat and BaÄ ka regions ( Vojvodina , in the northern province of Serbia ) ; the 64 km Danube-Black Sea Canal , between CernavodÄ and ConstanÅ # a ( Romania ) finished in 1984 , shortens the distance to the Black Sea by 400 km ; the Rhine-Main-Danube Canal ( about 171 km ) , finished in 1992 , linking the North Sea to the Black Sea . There are three artificial waterways built on the Danube : the Danubeâ `` Tisaâ `` Danube Canal ( DTD ) in the Banat and BaÄ ka regions ( Vojvodina , northern province of Serbia ) ; the 64 km Danubeâ `` Black Sea Canal , between CernavodÄ and ConstanÅ # a ( Romania ) finished in 1984 , shortens the distance to the Black Sea by 400 km ; the Rhine-Main-Danube Canal ( about 171 km ) , finished in 1992 , linking the North Sea to the Black Sea .