The Buna is a short river in Bosnia and Herzegovina, left tributary of the Neretva. Its source (Vrelo Bune), a strong karstic spring, is near the village Blagaj, southeast of Mostar. The Buna flows west for approx. 9 km and joins the Neretva near the village Buna. River Neretva in Mostar, 2004 Neretva is a river in Bosnia and Herzegovina and Croatia. ... Karst topography occurs when a landscape is marked by underground drainage patterns. ... Location in Bosnia and Herzegovina General Information Mayor Ljubo Bešlić (HDZ) Land area 1175 km² Population (2004 census) 125,448 Population density 95. ...