The olm is the only amphibian in Europe that lives in caves. This salamander from the family of ‘proteidae’ is a Dinaric Alps endemic species which lives in underground lakes and quiet underground streams and rivers of the Dinaric karst. It can be exclusively found from northern Italy, Istria and costal Slovenia to Dalmatia and Bosnia and Herzegovina. There are 46 underground locations where you can see the ‘white man fish’. Trebinje has the only olm observatory in the world. It is located in Vrtuljak cave in Gorica neighborhood. The purpose of it is to study and preserve this endemic species, as well as to popularize it for tourism purposes.