A real mystery, but good golly what a beautiful mystery. The Buna isn’t Bosnia and Herzegovina’s longest or most exciting river but it gives its compadres a run for their money in the curiosity stakes, emerging as it does from this most famous of cliff-faces. Many a speleologist has entered in the hope of pulling back the veil on its secrets but many a speleologist has come up short, and the spring of the Buna remains a BiH holy grail. A great example of a karst river in this most karsty of areas, you’ll struggle to come across a more picturesque spring than the beauty of Vrelo Buna.