The entrance, 2.5 metres high by 2 wide, narrows very quickly forming a very tight passage, through which we will descend a couple of metres, finding ourselves in a small L-shaped chamber and taking the main direction of the joint.

A very selective passage allows entry into the joint 10 metres from the bottom, which can be descended by opposition. In a corner formed by a small widening, we will find a hole that communicates with another joint parallel to the main one and with which it joins at the upper part. The narrowness makes progression through the lower zone of these joints impossible.

If we climb the main joint above the entrance mouth, the width is greater and allows passage a few metres further, until overcoming about 20 metres where the passage becomes so narrow that it hinders all progress in altitude.

From the outside, about 60 metres above the mouth, some windows can be seen that could connect with the cavity. A climb allowed access to them, but the passage is so narrow that it makes progression towards the interior impossible.

Left-hand shaft of 37 m of vertical drop at el Bruc.