The river Trešnjica springs on Povlen and after 23 km it flows into the Drina near Ljubovija. Trešnjica is a fast mountain river of cold water, relatively unpolluted. It can swell couple of hours after the rain and then it could be dangerous for visitors who do not stick to the marked paths around it.

 

Immediately before the confluence with the Drina, the river created a 152m deep limestone gorge with vertical cliffs. This area is a nature reserve, most of which is covered with forests and bushes with domestic hornbeam, Turkey oak, black pine and spruce. The climate is moderately continental, with fresh summers and cold winters, and the sub-mountain climate occurs at higher altitudes. The average annual temperature is around 10 degrees Celsius, and the average annual rainfall is 774 mm. From the local winds there are Severac, Bosniak, Krivac, Vihor, Smušac ... Part of the area of the river Trešnjica (about 14 km) is  under protection as a natural asset of great importance and is classified in the first category of protection as a special nature reserve "Gorge Trešnjica River ”. It has been protected by the state due to the preservation of the habitat and population of the rare griffon vultures. In appearance, the griffon vulture is a typical Old World vulture with a white bare head and neck and a yellow beak, wide wings and short tail feathers. Like other vultures, it feeds on carrion, mostly dead animals that it finds by cruising the sky in wide areas, flying in flocks. It often grunts and hisses, especially when eating. It nests on the cliffs of the mountains, laying one egg at a time. The birds are naked after hatching. Sometimes they form colonies. The gorge is also protected due to geomorphological forms and valuable ethno heritage. Most of the plant species in the gorge are endemic and relict.

 

Specific for the Trešnjica canyon is that every spring the fish huchen, the "queen" of the Drina, emerges from the Drina to the natural spawning ground.