The Vrbas is a major river with a length of 250 kilometres (160 mi), in western Bosnia and Herzegovina. It is a right tributary of the Sava river. The city of Banja Luka is located on the river banks.

The Sava is a river in Central and Southeast Europe, a right-bank and the longest tributary of the Danube. It flows through Slovenia, Croatia and along its border with Bosnia and Herzegovina, and finally through Serbia, feeding into the Danube in its capital, Belgrade. The Sava forms the main northern limit of the Balkan Peninsula, and the southern edge of the Pannonian Plain.