The small entrance leads to a 9-metre shaft descended by a slope 3 metres from the entrance, where it widens considerably, making the use of a rope necessary. The floor of the first shaft is elongated, 2 metres wide by 8 long, with the ground sloping down towards the North. On the East side there is a 3-metre drop leading to a lower chamber, below the floor of the first shaft, while at the North end the interference of a fissure can be seen that will allow us to descend deeper.

The second shaft, 13 metres, is at first quite narrow, but after a bit of effort it widens considerably and allows us to enjoy some space, with a 4x2 metre section, to descend the 10 metres of vertical that remain after the narrow passage. On the West side the fissure through which we entered the shaft continues, but it is very narrow and full of sediments. The floor of the second shaft is rectangular. On the North side a hole appears that gives access to the third shaft. This is 10 metres of vertical, and is reached through a hole 1 metre in diameter that leaves us on top of a wedged block. From here the vertical is direct to the bottom of the cavity. The floor of this last shaft is formed by a ramp descending towards the North, and meets the perpendicular fissure that goes in a few metres further down and becomes increasingly narrow and full of stones that make continuation impossible.

The shafts of Torrent Fondo were originated, first of all, by the deep excavation of the torrent, which has caused very pronounced side walls and, at times, difficult to stand upright on, which is why large blocks of conglomerate have come loose. The rigidity of the rock does not let it break up into small stones of normal dimensions, and forces movement in large rocky masses that leave empty spaces between the detached rock and the mountain. These voids are the shafts of Torrent Fondo.