The Buso della Rana is a natural cave with the explored trail of over 35 km. Until 2011 it was considered one of the longest caves in Italy with a single entrance, but in recent times passionate cavers have found a connection with another cave nearby, which (unfortunately or fortunately) made it lose this record, however gave it 15 km of new tunnels.

The entrance (open for everyone) is majestic and the temperature at this point is constant throughout the year: approximately 13-15°C. The interior of the Buso della Rana is wonderful, but to visit it is essential to be well equipped and accompanied by experienced cavers. Inside the cave there are indeed tunnels and ponds, which are absolutely dangerous for inexperienced people; also there are some areas, which get flooded instantly in times of bad weather, which then makes it impossible to reach the exit.