Tresviso Caves Project

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T516: Cueva de la Cabeza de Vaca

(Cowshead Cavern, Cueva el Agua en Sobra, Cheese Cave, Ogof Pen Y Buwch, Cueva de la Cebeza de Vaca)
Area:Tresviso
East, North:362314, 4790563 (nearby)
Coordinate Quality:GPS
Long, Lat:0, 0
Elevation (m):894
Length (m):1877
Depth (m):47
System:
Active Lead:
Survey Available:

Approach
In the Sobra Valley, follow the main track down into the valley, as if heading towards Cueva del Marniosa. At the first obvious split in the track, take the left hand route down to the obvious cabanas in a clearing. Turn east and head down the valley, with a small river to the right.

The path leads down through a stream to an obvious resurgence on the left. The cave is located on the northern side of the Sobra Valley and would appear to be a resurgence for caves on the western end of the Tresura range.  An alternative route through the field on the left of the track, leads to a grassy slope down to the same entrance.

Entrance
Small resurgence. Entrance chamber splits. Right is a locked cheese cave, believed to be no more than 30m long to a dead end, and to the left is the main Cowshead Cavern entrance.

Description
The passage follows the stream upstream in easy walking passage. After about 30m, the roof lowers to an intermittent sump / flooded passage. A little way back a slope on the right leads to a stoop under an arch and an obvious hole in the roof above. This is a 2m climb into a sideways squeeze and thrutch into a small loose boulder choke. Continuing straight on and then up enters another larger boulder choke chamber.

From the chamber, right leads to a few small climbs up and down and the original site of a Musk Ox skull (now in the Cantabrian Museum) - originally thought to be a cows head (hence the name of cave).  There are a few other calcited skulls in the area.  Climbs in the roof lead to small grottoes with no way on, and the small holes in the floor of the choke lead back to the initial climb up from the stream.

Back at the main chamber, straight on and then down to the left through the boulder choke, leads back to the streamway. The streamway continues for around 150m of fine river passage, until the ceiling opens up into a “canyon chamber” around 20m high.

Above you when the ceiling opens up is the access to some upper levels Cámara de murciélago azul, which nearly reach the surface. This is accessed via an up-pitch, with chord left in place for re-rigging with a 30m rope as a pull-thru, and an in-situ pitch further up. Climbing down to the left of the rebelay (before the in-situ rope) is an access into the Milkloft, but this is a more delicate and tight way in - so is not recommended.

From the canyon chamber, following the stream leads through some collapsed rocks to a wet duck and a too-tight rift. 

A bolt climb at the far side of the chamber, rigged with chord for re-rigging, leads to an alcove which then drops down into a perched sump (undived) called Udder sump.

The main way on requires a choice of 3m climbs up to the right, into a calcited fossil level at the end of the chamber with some nice gour pools. After around 10m, an obvious  calcite ramp down to the left regains the streamway.

Staying high in this fossil level, over the top of the calcite ramp, leads to a calcited level a few metres above the stream. About 10m from the ramp, the ceiling extends upwards and the calcite can be climbed and then chimneyed up to the Milkloft. The Milkloft is a well decorated collection of high level passages, which connects to vantages over the canyon chamber and the pool chamber.

Back at the bottom of the calcite climb, the streamway is followed upstream for another 50m to an obvious pool in a large chamber. 

There is a too-tight inlet to the right of the pool, and various high level shelves and holes around the chamber. 

The way on is across the pool to the left, and up via a calcited climb that is quite exposed. It is possible to rig a handline from the top of the climb. At the top, a large tube leads to 20m of large passage and a window overlooking Sump 1. 

Passing under the handline climb, follows a tight rift for around 15m with the stream running in the floor. This leads to a 2m diameter sump that almost certainly connects into sump 1.

A low sandy tube on the right of the upper passage leads to a sumped tube filled with sand, also likely connecting to sump 1.

Sump 1 is 100m long, and 10m max depth, which is reached very soon in the sump and then gently rises to an airbell 55m in, before a further 45m of sump at 6m depth reaches the far end. 

A loop can be found heading in the opposite direction in the near-side sump pool, this links round to the deepest point (10m) through narrow passage and passes a junction which is likely to connect to the sandy crawl/dig before Sump 1. There are multiple passages heading off from the trunk route of Sump 1, which are presumed to all connect into a deep route through the sump.

Sump 1 emerges in a tall rift, with a stream running into the sump. A sloped climb reaches a level 2-3m above the streamway, which passes a couple of traverses over the water before the level rejoins the stream. Beyond a 1m deep canal, a flaky cascade climb of 1-2m is negotiated before a stooping section leads to the Sump 2 pool. 

Back and to the left of Sump 2 is a slope which leads to a high level oxbow, linking backwards to a passage above the cascade climb. The slope can be followed rightwards to a 4m climb into a roof tunnel (unexplored) which seems to be separate development from the streamway/oxbow.

Sump 2 is 4m deep and 8-10m long, emerging in a large chamber where the stream runs in through a tunnel crawl. High level rift passage can be seen above the tunnel but isn’t the main route on, so is left unexplored. Following the water, a constriction is met about 30m upstream from Sump 2. Despite being narrow and at water level, this is the easiest/safest way on. Further upstream a large choke is met (“Digital Love”). The way on starts at water level but soon you must climb up through boulders on the left hand side, keeping to the left wall through a number of boulder constrictions before emerging into a walking-sized passage atop large boulders.

Step across the boulders to reach a slope heading up and right, through a sizable hole between boulders. Looking up after this hole, you can see the rift stretching far above, however this looks very loose with large perched rocks so is best left alone! The way on is back down to stream level down a loose slope. Once the stream is reached it soon turns into The Lake, a 2m+ deep canal, with ledges either side for most of its 30m length.

Once you get out of The Lake, a loose slope rises up away from the stream level. It chokes right at the top, but the way on is through a calcited tunnel (“For Whom The Twelve Tolls”) against the right hand wall towards the top of the slope. At the bottom of the tunnel the floor drops away ~4m into the stream, so you must traverse carefully round to the left hand side, to reach a boulder pile back at stream level. To the left of these boulders is a tall unclimbed aven +27m, not far from the location of the radiolocation transmitter from the 2024 experiment.

Climb down the boulders to regain the streamway. The large “Main Chamber” is best reached by a handline bypass, as the streamway route leads into the boulder pile in the bottom of the chamber, very loose and narrow. Instead, climb up the rift into the roof almost as soon as you regain the streamway. This is currently rigged on Rob Middleton’s rope from the 2018 expedition (rope is dated 2014), but is free-climbable if needed. 

Following this route upwards reaches a window in the Main Chamber directly opposite the 8m waterfall. A narrow/loose traverse around the chamber’s edge reaches the boulder slope which drops down into the centre. The chamber itself is some 40m+ tall.

The route up out of the chamber is an 8m pitch, currently rigged on orange 9mm rope and tied well away from the waterfall (still reachable from the floor). This is backed up to green dynamic, doubled-back multiple times. Climbing up the pitch reaches a walking passage above the narrow streamway canyon, after 20m the streamway can be joined to reach the dive base of Sump 2.9.

Sump 2.9 bypasses tight dry rift and is easier for dive gear. Approx 20m long and 5m deep. 

If attempting to dive Sump 3, it is best to kit up before Sump 2.9 as the base is much nicer, and the passage between  Sump 2.9 and Sump 3 is easily negotiated, requiring minimal de-kitting in between. Dry cavers can bypass Sump 2.9 by climbing through a narrow hole in the roof, above an obvious ledge just before Sump 2.9. This goes upwards and reaches a narrow rift (“The Fluffer’s Rift”), where numerous pits back down to stream level are passed before a calcite slope leads directly down into the Sump 3 pool.

Instead of descending to Sump 3, you can continue climbing up The Fluffer’s Rift to reach the top, some 15-20m above stream level. According to historic survey info this leads to a high level passage of several hundred metres, though this wasn’t explored in 2024. It would require bolting equipment to discover properly, as the very top of the rift will need protection (not technically difficult, just a long way to fall on the wrong side of a sump). About halfway along the stream level passage between the far side of Sump 2.9 and Sump 3, the passage has a sharp bend, in this corner there is a climb up to a high level rift passage which carries on in the same direction as Sump 3. It is unlikely that this will bypass Sump 3 (clear signs of exploration from the ‘80s) although it has a number of windows into parallel rifts, which were left unexplored in 2024 (low quality leads).

Sump 3 drops down to -18m, passing over a blind shaft, before dropping again down to -31m, where an elbow is met.  The sump then ascends to the surface after 95m.  . This enters a high rift chamber with possible leads in the roof but only 5m later Sump 4 is reached.

Sump 4 drops to -7m depth and then ascends, after 30m, into airspace with continuing passage and some high level leads.  10m further on Sump 5 is reached.

Sump 5 descends down to -21m passing an unexplored shaft then back up to a col at 17m before descending again to 25m where a shaft drops down to -38m.  The sump then continues for a further 60m at a depth of 37m to 39m and the current end is at a rising shaft. Total length is 135m and ongoing.



2018 Extensions Just beyond Sump 1, on the right, is an ascending ramp heading up above the upstream sump pool. This climbs steadily for 20m until it reaches the top of a muddy climb back down. The climb (5m) is slippy but passable without equipment and leads after 10m to an un-dived static sump, and another rising ramp to the left. This ramp climbs and heads rightwards into an inclined rift, with both ascending and descending passages. Descending here leads past some attractive formations to a 5m pot into a sump pool(this is the air bell in sump 1), a continuing slope leads to another sump pool after a further 8m which probably connects underwater. Back at the junction climbing up and rightwards in the rift gains an improbable rightwards continuation which leads after 20m to another descending ramp, (there may be a tight way in the rift, climbing above the rightwards continuation but it looks poor, and presumably very near the surface). The descending ramp leads after 20m to a small muddy crawl which eventually leads to a mud choke. 

Reference
S.W.C.C. (1986)
Grandes Cuevas Y Simas de Espana (1998)
T.C.P. (2016-2024)

Images
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