 Downstream of the Iron Gate, the river is free flowing all the way to the Black Sea, a distance of more than .The Danube connects with the Rhine–Main–Danube Canal at Kelheim, with the Donaukanal in Vienna, and with the Danube–Black Sea Canal at Cernavodă.Apart from a couple of secondary navigable branches, the only major navigable rivers linked to the Danube are the Drava, Sava and Tisa.