Vjetrenica (which means 'wind cave') is the largest cave in Bosnia and Herzegovina. In the warmer parts of the year a cold air blows from its entrance. This unique cave system runs from the edge of the gorgeous valley of Popovo Polje all the way to the south and is about 6 km long and 25 m deep.
Vjetrenica has ancient cave drawings of bears and leopards estimated to be over 10,000 years old. It is now on the list for UNESCO World Heritage Site protected areas in Bosnia and Herzegovina. In terms of its biological diversity it is one of the richest caves in the world. The Cave is home to many small lakes and endemic types of shellfish only found in deep underground aquifer systems. In a scientific sense, Vjetrenica has been the site of many different forms of research, which may be traced back to the 16th century.