Interesting geographical formations characteristic for limestone are relatively often in Eastern Serbia and in Serbia in general. One such formation is powerful Krupajsko Vrelo spring located on mountain Beljanica western slopes close to town of Zagubica.
The spring has been partially captured and its waters power nearby wool and flour mills, still in operation. This is why the cave entrance is partially submerged by the pond that has formed since. There is also powerful thermal spring nearby with a water temperature of 26.50 C. Krupajsko Vrelo spring enjoys government protection.