It is the finest example of an underground karst river. It flows out of a 200m cliff wall and single-handedly creates the Buna River. Unsurprisingly, the Ottoman sultan was impressed, and ordered a tekija to be built right next to it. This 16th century house was built for the Dervish cults and is still one of the most mystical places in all of Bosnia and Herzegovina. It is open to visitors all year round and serves cold drinks, tea and Turkish coffee in a beautiful garden overlooking the source of the River. The region is also known for the diversity of its flora and a number of endemic species.