Buna is a river in Bosnia and Herzegovina, left tributary of the Neretva, which flows about 15 km downstream from Mostar. Buna is 9 km long. Buna is coming from karst spring Bunice, located below a steep limestone section area Rudine and from springs beneath the limestone section in Blagaj. The highest water levels are in November, the lowest in June and August. Before the source itself, Buna flows underground 19 and a half kilometers.