Drežanka springs at the foot of one of Bosnia and Herzegovina's largest mountain, Čvrsnica.

The catchment area and the course of Drežanka are situated between Čvrsnica (2226 m) in the north and Čabulja (1776 m) in the south.

It flows into the Neretva in the immediate vicinity of Donja Drežnica at an altitude of 112 m. The average drop of Drežanka is 17 ‰.

With all its visible layers of rock, both at the bottom and at the top and above it, the Drežanka canyon is a considered by researchers an open-air paleontological museum, where it is possible to find fossils from the geological past spanning as much as 200 million years, from the Triassic, Jurassic, Cretaceous up to the upper Eocene.

The Drežanka source is about eight kilometers away from closest settlement and is a popular hiking trail approximately two-hour walk in length.