The cryptoportico constructed to regulate the flow of water in periods of flood, seen from the rear of the baroque altar.
This is the starting-point for the speleological tour of the cave, which was also the home of the Ursus spelaeus, the European cave bear.

Exploring a fascinating underground world

The Cave of San Giovanni d’Antro is more than a supremely interesting example of art and culture; it is also an underground labyrinth of extraordinary complexity. To the rear of the baroque altar, the cave shrinks into a narrow tunnel eroded by water; it is from this tunnel that the labyrinth of branch tunnels spreads on multiple levels, of which to this day 5,400 metres have been explored. Visitors can admire funnels, sinkholes, streams, lakes and salt forming the spectacular concretions which are typical of this underground world. The cave is an active site, and continues to present fresh challenges for speleologists. Tourists can visit the cavern in complete safety (wearing protective headgear) on a path which reaches the first 300 metres; but this is sufficient to give an appreciation of the morphology of this splendid marvel of nature, with the constant presence of flowing water and a number of interesting stalactite formations.

As well as the standard tourist visits, more adventurous explorations are organized at regular intervals.

Going beyond:
a labyrinth of emotions carved out by water

While the Cave of San Giovanni d’Antro is used as a training ground and research area for numerous groups of speleologists from Friuli Venezia Giulia, its deepest and most difficult recesses are as yet unexplored. The presence of water, which can vary in flow and levels, and the narrowness of many of the passages make thorough exploration an arduous task. However, as may be seen from these photographs by the Natisone Valleys Speleological Group (photos by Fabrizio Bosco), this labyrinth of karst rock offers enthusiasts a wealth of emotions.