The Calgeron Cave is the most popular with speleologists. Galleries, ponds and stalactites create a suggestive environment
This is the most popular cave in Trentino with speleologists. Its entrance is at 470 metres a.s.l., just a few kilometres to the east of the Bigonda cave, with which it probably forms a single huge complex. Overall it is about 3610 metres long and the initial 2 km stretch can be visited the year round. The remainder of the cave is open only to expert potholers with the necessary equipment and only in winter.
The cave features large horizontal galleries with ponds, syphons, sources of water and rivers, which, especially in spring, can flood large stretches of galleries. Extremely spectacular is the 80 metre long cavern, while of the 11 lakes, the most interesting is the seventh, over 40 metres long and 4 metres deep. A thick layer of white clay found in a side shaft was probably deposited during the Riss glaciation, which would date the formation of the cave back to at least 250,000 years ago. The initial stretch of the cave is decorated by some suggestive concretions, such as a calcite basin several metres wide, stalactites and stalagmites.
The Calgeron cave can be reached in about half an hour on foot from the road that leads to Selva di Grigno.