Esquerda del Riu Set is an open-air cavity, covered by invasive vegetation that makes it difficult to locate and access (Pinus halepensis, Juniperus phoenicea, Quercus coccifera). The fissure begins with two lateral openings, one at each end, followed by a passage narrow in width until reaching the deepest part, where the space widens notably. The cavity has two turns of almost 90 degrees, and in one of them, two large rocks partially block the way, forcing you to climb to continue. Towards the central part, a small crevice opens in a southerly direction. Sandstone forms the whole of the cavity, and it can be seen that the formation may have been caused by a rockfall.