Despite its low discharge and relatively short flow, this river takes a significant place in Bosnia and Herzegovina's Dinaric karst's geology and hydrology.

It begins at the south-western slopes of Prenj mountain, where it is called Gornja Bijela ("Gornja" in English: "Upper"), and flows in direction of north to south-southwest and into the Neretva at Bijela village in the region of Drežnica Donja and Salakovac.

What is unique here, in case of the Mostarska Bijela, is that cave roof of its underground section is opened to surface in form of very narrow gap in many places, enough only for small amount of light to enter the cavernous river course.

Although very difficult underground course is still traversable, and thus attractive for tourists, mountaineers, especially for canyoning and speleologist.

Beautiful karst phenomenons of deep canyons, underground waterfalls and caves in Mostarska Bijela valley will be destroyed, or at least covered by the asphalt, concrete or stone fill from the tunnels.