The Una (Serbian Cyrillic: Уна, pronounced [ûna]) is a border river between Bosnia and Herzegovina and Croatia and a right tributary of the Sava river. It is part of the Black Sea drainage basin, and its watershed has a size of 10.200 km2, of which 8.080 km2 belongs to Bosnia and Herzegovina, and 2.120 km2 to Croatia. The total length of the river is 212 km. The source of the river is located in the town of Donja Suvaja in Croatia, and its mouth is located near the town of Jasenovac, on the border with Bosnia. The largest right tributaries are the Krka, Unac, Krušnica and Sana rivers, and the largest left tributary is the Klokot river. Its longest headwater is the Unac river. The largest and most important city located on the river is Bihać. Other, important cities and towns are Bosanska K