or Tisa River
River, western Ukraine, eastern Hungary, and northern Serbia and Montenegro.
Rising in the Carpathian Mountains of western Ukraine, it flows west, forming a section of the Ukraine-Romania border, then continues southwest across Hungary and into Serbia and Montenegro to empty into the Danube River above Belgrade . It is 619 mi (996 km) long. The Tiszalök Dam (1954) forms the largest reservoir in Hungary. The Tisza is navigable for light-draft boats for about 450 mi (727 km).