An approximately triangular entrance of 2 x 0.7 metres, cut off to the S by a small channel, gives access to a descending ramp gallery at 45º, with an earthy floor and a width that ranges between 0.5 and 1.5 metres. Next, an earthy step 2 metres high allows us to reach a high gallery (1.5 – 5 m.), with a very irregular ceiling and a floor of pebbles and earth. This passage has a variable width (0.6 – 1.5 m.) and descends at a gradient of 35º to a one-metre step, formed by embedded pebbles. A little further down from the step opens a small pit 4 metres deep that connects with a lower gallery about 9 metres long which at its S end is choked by sediments and at its N end leads to a small pit of 3.5 metres at the bottom of which, full of pebbles and mud, is the point of maximum depth (elevation – 21).

If we return to the pebble step, we will see that in front of it the gallery continues, now as an ascending ramp of 30º and 0.5 -0.8 metres wide, with the floor full of gravel from the disintegration of the conglomerate and a length of 8 metres. The ceiling is of irregular height (2 – 6 m.). In the upper part of the joint, some fitted blocks form a false upper gallery.

The whole cavity is structured on two levels on a joint of approximate direction N25E-S25O.

The erosive and rounded forms of the entrance sector and of the lower gallery, more or less masked today by dissolution phenomena, suggest that the pit functioned as an emissive cavity within the whole of the karst system of the fonts de Rellinars.