Through the wider entrance (M-15) one enters a shaft of -5 metres. The base measures 7x4 with a steep slope and has two continuations. The first, at the end opposite the place where we descend, is a 6-metre gallery that ends obstructed. The second begins after a short step that leads into a straight gallery 22 metres long with a descending floor, where the point of maximum depth is found (-17 metres). The continuation is through a small room with a low ceiling; on one side of this and through the ceiling one reaches a gallery that rises suddenly and sits a few metres above the entrance room of the cavity. From here two galleries branch off: one open to the sky, which is none other than the entrance fissure that after a few metres leads back to M-15; the other, located at the other end, is a narrow passage that is soon cut off by a 2-metre step that is even narrower. In front of this pit and at ceiling level one can reach the continuation of the same gallery that after a crawl leads to the base of the 4-metre entrance pit of M-15. The gallery continues for about 15 metres until it is cut off by a climbable-down pit; at the base the gallery continues until it exits outside between some blocks.