Updated 30th August 1998; 19th February 1999; 27th October 2001; 9th November 2003; 17th January 2004; 26th September, 28th October 2007; 19th December 2008

The cave entrance was gated in May 1998 although, on a visit during the summer of that year, the gate was found be unlocked.

A steep boulder slope leads after 30m to a 15m square passage with some 15m high formations. The cave ends at a calcite blockage, above which the decorated route passes graffiti before choking. To the right, past a pool, the passage splits: up to the left narrows and closes in, while to the right, in an alcove is an engraving of a deer (see below). On the left of the main passage is a 10m high column with the top half fallen over and wedged. There are also a view-hole through the calcite on this southern wall into a small chamber.

On the left, near the entrance, a climb (rope useful) over flowstone leads to a chamber with daylight in the roof (see entrance pictures) while further on, on the left, a short climb up and down leads to a chamber. Up to the right, over painted calcite, enters a short crawl to a small chamber and a short drop to a choked hole.

Some 70m into the cave, on the northern side, a clamber up calcite to a short rising traverse meets a 9m pitch into a choked chamber.

The cave is an archaeological site (Matienzo archaeology article) with bear, hyena and bison bones and a single possibly Magdelenian engraving of an animal without a head but with a spear in its side, at the end of the main passage. (See Strauss Lawrence Guy, 1992 p133, 176). In 1998, a paleolithic deer jaw bone was recognised at the base of the entrance boulder slope. Further engravings are described in an ACDPS publication, 2002 (not seen). The finds are put into sequence in Ruiz Cobo Jesús and Smith Peter et al, 2001. The site was apparently first investigated by workmen in 1956.

The bat Rhinolophus ferrumequinum has been recorded, while Notenboom (Notenboom J and Meijers I, 1985) found the following in 1984: Syncarida/Bathynellacea, Insecta and Oligochaeta.

References: Fernández Gutiérrez et al, 1966 (survey and photo); Kendal Caving Club and Manchester University Speleological Society, 1975 (survey); Mills L D J and Waltham A C, 1981 (survey); Smith P, 1981a; Smith P, 1981c ; Corrin J S and Smith P, 1981; Smith P, 1981b (survey); Corrin J, 1983c; Manchester University Speleological Society, 1982 (survey); Smith P, 1986c (survey); Notenboom J and Meijers I, 1985; Meijide Calvo M, 1982; Balbin R et al, 1986; Muñoz E, 1988; Smith P, 1988; Strauss Lawrence Guy, 1992; anon., 1994a (Easter logbook); anon., 1997d (Autumn logbook); anon., 1998a (Easter logbook); anon., 1998b (Whit logbook); Corrin Juan, 1999; Fernández Ortega F, Valls Uriol and Maria del Carmen, 1998 (photo); Smith Peter and Ruiz Cobo Jesús, 1999; Ruiz Cobo Jesús and Smith Peter et al, 2001 (includes photo); Smith Peter, 2002; Ruiz Cobo Jesús and Smith Peter, 2003; anon., 2007d (summer logbook); Corrin Juan and Smith Peter, 2007; Corrin Juan, 2007a; Ruiz Cobo Jesús et al, 2008; Corrin Juan, 2013a
Entrance pictures : yes
Underground picture(s): yes
Detailed Survey : 1:1000
Line Survey :
On area survey : with Coberruyo, Lara-Lennon: low res  high res
Survex file : yes (Amended magnetic declination December 2013 to align with Eur79 grid and coordinates altered to fit ETRS89 datum, April 2014.)