767 Cave of the Wild Mare
Hornedo 30T 448072 4801526 Altitude 69m Length 594m  Height 14m [30T 448064 4801541 is a GPS'ed point in the stream bed to the N of the entrance, part of a surface survey to the river]

Updated 12th November 2002; 16th April , 25th July, 3rd October , 8th November 2008; 24th February, 5th May, 2nd November 2009; 6th January, 19th, 27th May 2011

The opening lies a few metres above the main river at the head of a normally dry river bed. The entrance is 3m high and 6m wide with a strong draught emerging from it. On one visit at Easter 2008, it was reported that huge amounts of water were emerging after one days continuous rain - probably equal to the river at Matienzo in moderate flood. This raises the possibility that this site is acting as a flood overflow for Fuente Aguanaz, 1.5km to the west. It is assumed that the cave acts as the resurgence for all the water in Torca la Vaca, site 2889. Despite complete re-exploration, extensions, pushing and resurveying over four days in the summer of 2008, no link was found with the upstream cave, although water in Wild Mare was muddy - due presumably to the explorations in the watery sections of Torca la Vaca. (Some suggestions about the source of the water are shown here.)

The passage swings right to hands and knees crawling on sharply eroded rock with rippled sand. After 40m it is possible to walk and after 60m pools are met on the left. A branch on the right soon degenerates into an almost flatout crawl over eroded gour pools. This passage draughts strongly and has been pushed to where it splits and becomes too small. Part way along is a low sandy bedding which has been dug to a cross rift 15m high and 20m long which draughts slightly. This was climbed in 2008 to a strongly draughting passage which choked.

The eastern passage has deep water and passes through areas of breakdown with avens. The route ends at deep water in a cross rift. The water emerges from beneath the southern wall of the rift. This was dived in 1995, through the 50m long Sump of the Wild Eels to 50m of passage and further cross rifts with draughts but no apparent way on. Small sumps in the floor also offer little hope for extension.
At Easter 2011, divers in Torca la Vaca passed through a 25m long sump to emerge in a chamber with a another sump. This may or may not have been the upstream end of Sump of the Wild Eels.

Climbs in the rifts before the sump have been attempted but protection and/or a maypole on the rotten rock may be advisable. The main draught appears to come from a high cross rift just before the sump and, next to the sump, a hammered-out, narrow rift has been pushed to a choke with a possible passage about 5 to 10m above. In summer 2009, the last rift at the sump was climbed, but there was no draught and no way on.

A diagram of the hydrology of the San Antonio - Hornedo - Cobadal area drawn after Easter 2011 can be found here.

Reference: anon., 1989 (logbook); material in file; anon., 1994a (Easter logbook); Corrin J, 1994b (survey); anon., 1995c (logbook); Corrin Juan, 1995a; Corrin Juan, 1996 (survey); anon., 2008c (Easter logbook); anon., 2008e (summer logbook); anon., 2009c (summer logbook); Corrin Juan, 2011; anon., 2011b (Easter logbook)
Entrance pictures : yes
Underground picture(s): yes
Detailed Survey : 1:1000 from 1989 / 1995  10Mb pdf file: 2008 resurvey and extensions
Line Survey :
On area survey :
Survex file : stand alone   with Torca La Vaca and others (Easter 2011)
Passage direction rose diagram (Patrick Warren): yes