The view of the abyss where the second part begins is striking, the regularity of the rounded wall is interrupted here and there by crests and spurs of rock, whereas the “floor”, if you can define a 70-degree gradient as such, is marked by a bend which was carved by flowing water in a quite recent era.

The path descends directly to the bottom with a steep and tortuous staircase, halting only 45 metres further down in the "Hall of Voices", a wide hall with an elliptic shape where the unusual wall formation creates evocative sound effects.

Past this room the passage lowers considerably, forcing visitors to bend down for a few steps; further on the ceiling rises again, until it reaches a height of at least ten metres in the "Tunnel of Valleys", where we later take the path going up to return.

Proceeding downwards, having passed another 10-metre "drop", we enter the "Acheronte Hall", situated at the very bottom of the karst system, where along the contact point between schists and limestone, three small underground streams join up. The environment is distinguished by the continuous presence of water and by impressive examples of erosion which model the walls and ceiling in a bizarre manner. Silt, a very fine mud, can be seen everywhere in great heaps on the floor. It creates "miniatures" that remarkably reproduce models of mountains dug by valleys, gullies and canals.

The tour continues along the underground river through a smooth, round-walled gallery ending in the "Domed Hall", where the mysterious "siphon-lake"  originates. Beyond this the "Acheronte" river continues to flow towards a world still unknown.

The way back follows a steep pathway that connects the "Tunnel of Valleys" with the "Intermediate Tunnel". The walls of this latter tunnel are covered everywhere by countless grey formations, which remind us of images that have little to do with an underground environment: in some parts they resemble miniature forests of fir trees, in others a procession of little monks, underwater vegetation or groups of mushrooms.

The second tour last about two hours and also includes the first tour.