Updated 9th November 2003; 24th April, 9th October, 5th, 28th November, 18th December 2005; 15th May 2006; 27th October 2007; 4th, 5th May, 1st July, 24th October 2009; 6th January, 27th May, 5th October 2011; 4th December 2015; 20th May, 17th September 2017; 4th January, 5th, 30th May, 30th June 2018; 12th May 2019

The entrance is in one of the largest, bramble-filled depressions at the head of the La Gatuna bowl. The cave was first explored in 1982 and took on a new significance with the finds in the Sumidero de Cobadal in 2005 and Torca la Vaca in 2009. The entrance was eventually refound in 2005, some 140m from its position on the 1982 map. New bolts have been fixed near the head of the first pitch. A second, much more straightforward and strongly draughting entrance was then found in April 2017. This is site 4537 (Eastwater Entrance) which drops in at the boulder choke, south of On The Rocks. This should provide much easier access to the possible digs probably draining to Torca la Vaca.

From the old entrance, a stooping, vadose stream passage passes a small chamber on the left and degenerates to a flat out crawl where a thin coal seam can be seen in the left hand wall. A small sit-up chamber is reached where apparently modern pottery has been found, and then a squeeze through to a bolt on the left hand wall and a crawl through a revolting mud-floored pool to the head of the pitch. Immediately below is a 2m drop to a very tight slot but the tight take-off to the pitch is over on the right. (It may be that the 1982 position for the pitch-head bolt is on the pitch side of the pool, and this would make it easier to rig a double line).

At the base of the roomy 10m drop is a meandering rift that leads to the tight head of the second pitch after 15m.

At the bottom, the vadose continuation was explored for about 30m in 1982 with some awkward contortions in a sinuous rift. This passage continued with "excellent potential - the nearest surface water would seem to be over a kilometre away."
What draws the attention immediately at the base of the second pitch is a superb tunnel, about 7m high and 2m wide heading into the hill. This eventually splits into numerous passages, all of which soon choke. The main route enters a 7m high boulder-floored chamber where a continuation on the opposite wall ends at a draughting boulder choke with no immediate prospects. These passages were re-investigated over Easter 2006.

In November 2005, the awkward contortions were pushed to an enlargement after 40m and a short climb down into a streamway, about 1m wide and 12m high. This was followed down to an undescended "12m pitch". Upstream, heading south,  has been surveyed for about 80m to where the passage is blocked by a boulder run-in. There are avens off to one side and there may be a passage about 6m up in one of them. It seems likely that the upstream passage is fed by the large, vegetated shakehole to the west of the entrance depression.
A subsequent push at Easter 2006 found the unexplored pitch to be 20m. The stream at the base disappears into a low bedding under the right hand wall - "this is not a good digging prospect". A step from the second ledge of the pitch gives access to a wide shelf on the left and a blind cross rift. A passage can be seen at the top of the opposite wall, but the climb is a bit too exposed for one person with no protection. The only other possible lead left in the cave is the aven off the side of the stream passage with a possible passage about 6m up.

Western Series
This set of passages - the draughts and digs - were re-examined in the summer, 2017 and various "not very useful" short cuts found. These have been added to the Easter 2017 survey and, where possible, to the descriptions below. The source of the very strong draught through the Easterwater Entrance has not been found.
   At Easter 2009, a hole over the top of the p20 was reached and large chaotic chambers entered with 407m surveyed. A draughting passage can be gained by traversing high up in the rift above the p20. Several cracked mud floors are passed before a hole up through jammed boulders leads to a 5m wide chamber, White Russian, which is well-decorated.
   To the north, a passage leads to a large sandy chamber, Sex On The Beach, with a floor of white crystals. North from here leads to a choke; an arch to the west leads to a large pool with no continuation; to the east a sandy crawl (surveyed for 71m as batch 0394_18_01, January 2018) eventually leads to an 8m aven with no obvious way on at the top. All passages in this area either choke up or are too tight. Halfway between the two large chambers a rift passage to the east intersects an aven after approximately 8m.
   The main way south-west from White Russian enters a very large and well decorated chamber which requires a photo trip. The chamber was further investigated in July 2017. The run-in at the western edge was dug through to a low, draughting passage and another run-in. A small passage can be seen around to the right from which the draught emanates. This should be dug, possibly capped although it appears as a thin slab of soft rock and should yield to a few stout blows with a lump hammer. Quite a bit of debris was cleared from around the slab (January 2018) and the passage which approaches it was enlarged. There was a weak inwards draught going in to the dig during that winter visit.
   More work occurred here on a trip in April 2018 when all available stacking space in the small chamber before the dig was used. A flat-out passage was dug into a large aven/chamber. Ahead soon chokes but there is a dig on the left hand side. (Sketch from logbook) This extension was surveyed in April 2019 as batch 19-01, when other leads were also inspected but "crapped out".
   Also in January 2018, a squeeze in the floor following the flow of water, was investigated. It opened up briefly into a small sandy enlargement which had a couple of narrow, metre deep sandy pits.
    A hole in the floor in the chamber can be climbed down into about 30m of cracked mud floor to a choked chamber.
    On the inside corner of White Russian, a hole was excavated (January 2018) leading to very brief walking passage 5m long which goes round an acute right hand bend becoming too tight and appears to lead back towards the choke in White Russian.
    The way south through can be found by entering a small passage on the left immediately at the top of the boulder climb. This leads to the edge of a 4m drop down into a 7m high chamber, On The Rocks, which can be descended via a traverse round the the right followed by a climb down a slope. To the west here is a passage leading to a 7m climb down to the top of the terminal chamber (see below). The main way through On The Rocks heads south over collapsed boulders and passes a cracked mud floor directly below a set of anastomoses in the roof.
   The slope up (labelled N on the survey) was investigated in August 2017 and found to possibly link with known passages and point M. This is sketched on the survey but the various links should be clarified and surveyed. (See video.)
    At the southern end of On The Rocks a climb up over flowstone leads through a boulder ruckle (care!) into a 15m aven. A muddy passage to the east here gains a window overlooking a large chamber. In the summer, 2009, this turned out to link back to
   Back at the southern end of On The Rocks, a passage to the west reaches a large boulder choke entering high-up on the left. A route up between the boulders was followed for several metres. This area draughts strongly and is directly beneath a large surface depression. This is the route in from the Eastwater Entrance. A stream emanating from the base of the choke can be followed down a series of cascades to a blind pebble-floored chamber (approx. 5m diameter) where it sinks into the floor. There are several possible digs in this area but testing with smoke in 2017 showed hardly any draught and these digs have no hope. Just before the final 3m climb down into the chamber is a side-passage on the right that connects back to On The Rocks via the 7m climb described earlier.
Part way along the tight passage below the p5, excavation on the right entered a "nice flat out continuation". This entered a chamber with a route to a draughting dig and a tight spiral up on the east side. The total length of this extension is 55m.

As water has been tested to flow from the Sumidero de Cobadal to Fuente Aguanaz, it seems likely that this cave could drain westwards in a similar fashion. The 2009 discovery of eastward-heading Suit Wrecker Inlet passage in the Torca la Vaca System gives some credence to this. A push through the "terminal" choke in that inlet in 2015 extended the inlet to within 450m of the stream sinks in Cueva de Collada.

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

Dowsing was carried out in La Gatuna on 24/7/11 when various reactions were seen south of Cueva del Nabo and up to Cueva de Collada. See links below.

References: anon., 1982 (logbook); Corrin J, 1983c (survey); material in file; anon., 2005b (Easter & summer); anon., 2005c (autumn logbook); Corrin Juan, 2006a; anon., 2006b (Easter logbook); Corrin Juan, 2007 (survey); Corrin Juan and Smith Peter, 2007; anon., 2009a (Easter logbook); anon., 2009b (Whit logbook); anon., 2009c (summer logbook); Corrin Juan, 2010 (survey); anon., 2011d (summer logbook); anon., 2017b (Easter logbook); anon., 2017c (summer logbook); anon., 2017e (Christmas logbook); anon., 2018b (Easter logbook); anon., 2019b (Easter logbook)
Entrance picture : depression, 2005
Underground picture(s): entrance passage, 2005 : top of first pitch, 2005 : Easter 2018 : Easter 2019
Video: entrance   1st crawl 1  2  entrance passage 1  2   15Mb wmv top of first pitch to entrance : investigation from Eastwater entrance, August 2017 (YouTube)
Detailed Survey : from 1982: low res  high res   from 2005: pdf file   from 2006: pdf file   from 2009: Easter summer
Easter 2017 with new entrance : summer 2017 - Easter survey annotated with summer investigations : with Xmas 2017 survey
sketch 2018 Easter extension : Easter 2018 (includes detailed sketch) : Easter 2019
Line Survey :
On area survey : Dowsing reactions close to this cave : Dowsing reactions in La Gatuna (Article about the dowsing carried out in July 2011 can be found here.)
Survex file : yes (after Easter 2019) (Amended magnetic declination December 2013 to align with Eur79 grid and coordinates altered to fit ETRS89 datum, April 2014.)
Hornedo area (after Easter 2019)
Passage direction rose diagram: 30/6/2018