107 Cueva de la Hoyuca (Cueva de Riaño 2) (Cueva Uzueka)
Riaño VP51950002 Alt. 175m Part of the Sistema de Cuatro Valles
(Traverse length 42835m after summer 2000) Depth 87m (to upstream Llueva level)
The church entrance is at VN51709995 Alt. 175m; the corner entrance at VN51799997 Alt. 175m.

Updated 13 February 1998; 19th February, 18th April 1999, 12th December 1999; 14th March 2000; 16th September 2000; 23rd February 2001

An incomplete description follows.

• Route to Cueva Llueva
• Side passages

A cave of great variety, potential and in places, complexity. Cueva de la Hoyuca is the major segment of the Four Valleys System (line survey), the second longest cave in Cantabria. The cave continues to yield extensions, not just at the end, but in the entrance series which most people have neglected in their hunt for glory.

All of the water met in the cave eventually joins with some of the water from Cueva de Riaño (105), the water from Cueva de Carcavuezo (081) and then enters Cueva Llueva (114) and flows to resurge at Los Boyones (117) in Secadura.

If the route through the cave is known then a quick trip to the end of Trident Passages and back will take about 9 hours. The route sumps in at least two places and so trips to anywhere beyond the entrance series should only be attempted in dry and settled weather.

Route through into Cueva Llueva

Four entrances are known. The Church Entrance, only discovered in 1986, lies in a wooded depression next to the track, 200m below the church. A 6m high entrance drops down into a small passage. A short stretch of hands-and-knees in deep mud spoils the passage before it emerges into Quadraphenia at the first dog-leg. The unfortunate fact about this entrance is that a local farmer has used a nearby slot as a means of getting rid of manure. The deep mud may not be what it seems and perhaps should be checked out from inside the cave before attempting a trip through. Reference CE documents the gran depósito de estiércol and the possible consequences. During the 1994 recovery, a old door was used over the mud and this is likely to be still in place.

The "old" entrance (photo) is a couple of metres up a wooded slope at the bottom of a maize field. A short, constricted, draughting entrance crawl, with drops below, enters a small chamber. Straight ahead, a descending passage drops to a calcite-floored chamber and a further short slide down enters a maze of rifts where carbide arrows point back towards the entrance. A short climb up and a tight sideways squeeze (photo) pops out into Quadraphenia. (Back from the entranced chamber, a ladder up bypasses the tight squeeze and drops down into Quadraphenia). An alternative route through to Quadraphenia is from the second entrance chamber, where a climb up straight ahead leads to a crawl and climb down into the start of Quadraphenia, bypassing (and passing) the tight squeeze.

The passage enlarges from a slight stoop almost immediately and the next 560m is a trot along sandy-floored tunnels (photos 1 2). Large junctions (one of which brings in the Church Entrance passage) are negotiated by four left hand turns until a final right hand turn leads down to a low section into the stream in Pigs Trotters Chamber with its fine roof pendants. A short crawl over black cobbles meets a smaller inlet passage on the right. The inlet ends at a wet flat-out crawl on silt which sumps in wet weather and which often has to be dug out after the winter. The crawl is abandoned by slithering up into a small chamber on the left. A series of phreatic chambers is entered which are connected by short crawls. Some hundred metres of joint- aligned walking follow and this ends at a small boulder choke where the only way on is down into the low and wet Punk in the Gutter which lasts for only a few metres.

First River Inlet is passed on the left and the way enlarges. The stream is left to clamber over large, blocks and the only way to regain the water is down through a narrow slot.

The next 1000m of passage - the Gorilla Walk - is generally stooping-sized with a metre or more of water to wade through. At the end a major junction is met. Second River Inlet - the route into Cueva de Riaño (105) - comes in from the left while the way on is to the right. The route for the next 500m is obvious, through the Near Stomps, a large stream passage where the route is mainly over large sand banks. Gour Inlet is passed on the left and 100m further on, Obvious Junction is met up on the right. The river is left behind as twin passages unite at the start of Crossover Crawl. This is a generally low, sandy passage which ends after 160m at a walk down into the Third River.

Downstream, the next 540m are easy walking through Las Playas, the last 200m or so being on sand. The main passage is then blocked but a small passage with deep water (B Road) sets off on the right and the large, main route is soon rejoined on the other side of the collapse. One hundred and forty metres further on 4th River Inlet is passed and after another 100m of walking the entry to the Astradome is seen on the left.

By continuing downstream, 44 Chamber is reached and then the streamway becomes small phreatic passage for 340m to Sandy Junction, where the stream left at Obvious Junction enters on the left. The way on is downstream to face a boulder choke and the entry to Armageddon.

Armageddon is a 260m long heap of boulders, the first 20m of which are negotiated by following road works bunting (still there?) through the pile over drops into the stream below. Then by striking out and up (generally to the east) the boulders are left temporarily for a sandy walk, passing a large passage on the right - the entry to the Armageddon Bypass. A clamber down to stream level is then required and finally a climb to the east leads to a ladder pitch of 5m down through precariously perched boulders to the stream. The ladder has been in place since the middle of the seventies.(One or more trips have negotiated Armageddon without finding the ladder).

Armageddon is left behind and the water followed down into Paisley Passage, a 20m wide and 4m high bedding plane. The passage terminates after 200m at Green Choke with the water seeping away on the right.

The way through is over fallen slabs and scree to the left and all routes unite as a slither up to the head of a roomy bedding plane - the Giants Causeway. A walk down over large slabs leads to a pool and the stream is regained. The water is followed for 160m over sandstone blocks in a bedding 3 to 4m high. The water drops over a small cascade and the next 150m are negotiated in deepening water as Duckhams Sump is approached. The route is along the right hand wall and then out into deep water for 5m towards the sound of falling water. With little enough airspace at the best of times, muddy swirls on the roof show that the whole area sumps. The exit is up through a body-sized hole in the flat roof into an awkward rift which is followed upstream for 100m. It is then possible to climb up on the left into an area floored with large level-topped blocks and sand. The bedding becomes increasingly larger until a descent is made to a high inlet on the right. This marks the start of Rocky Horror.

Route finding on this 200m long pile of immense blocks can take a couple of hours though some routes have been marked. It is generally best to keep fairly high up on the right of the passage, leaving the stream down on the left. Passage walls eventually appear out of the gloom and the floor gradually reaches the roof. The stream can be found by dropping down on the right a few metres back from the end. A comparatively small and well decorated passage meets the stream after 80m.

A draught whistles out between boulders both at stream level and at a higher level and one route through the unstable mess was pushed in 1986. The loose connecting choke joins with the 1985 Extensions in Cueva Llueva (114) on the upstream side of the upstream sump. The route appeared to collapse behind the ors on the second trip through.

Other passages are now described by working through the cave from the main entrance

By dropping straight down in the entrance.................. Other bits off the entrance series, Lank?

At Easter 1994, a route from the 1st chamber in the old entrance to Quadraphenia was tackled up. This appears to involve a 5m climb up and a ladder down and cuts out all the complexities of the old route. The route was detackled after the summer of 1994 and is not recommended for rescue purposes.

A small passage off Quadraphenia, just after the first dog- leg, leads to daylight above, although this pitch has not been descended or indeed found on the surface.?

At the next junction in Quadraphenia, a right turn leads into 400m of smallish phreatic passage that can be followed to a number of branches, all of which choke.

Just before Pigs Trotters Chamber, on the left, two passages set off. The first chokes after 300m, the second swings back to Pigs Trotters Chamber - more detail needed? On the right hand wall of Pigs Trotters Chamber is 100m of minaret-type passage which leads up to Flashbulb Hall. On the left 20m before the hall is a small rift that enters a well decorated section with a pitch down into an unsurveyed and incompletely explored section - God Knows Passage?

In 1991 some 400m of passage, including Wardrobe Passage, was surveyed near to FB Hall and needs writing up by Lank. At Easter 1997, the pitch at the end of Wardrobe Passage was dropped into a fine rift in which was found a survey station note from 10 years previously, linking with God Knows Passage. (Survey notes have disappeared?)

The area was extended at Easter 1994 and the following description is taken from the logbook. A climb up the back of the Pig's Trotter leads to a complex of rifts which connect back into the main drag of Hoyuca's roof. A pitch from here drops in about 40m downstream of the Pig's Trotter. There is also a high level traverse which enters a bedding plane which continues low and wide. In a previously explored passage (?) a twisting aven rises for some 15m, draughting upwards, and ends at a gypsum chamber which appears to be a significant higher level. It closes down after about 20m in each direction.

Flashbulb Hall is a shattered, damp area of massive block collapse. Carrying straight on through the collapse leads to an unstable boulder area with deep holes in the floor. By traversing to the right, more than a hundred metres of passage is entered that splits and chokes. (Although most of this has been entered before, there appears to be unsurveyed passage that needs sorting). On the opposite wall to the point of entry, via an exposed traverse, Dog Series starts and is a complex series of tubes and avens. By laddering one of the 11m deep holes an immature streamway is entered and also a small passage that pops out 4m up the wall in Quadraphenia.

By continuing upstream at the first wet crawl, walking sized passage is reached. The stream is left where it emerges from a low section and a higher level phreatic tube entered. Awkward progress is stopped by the 9m Sima Baz. A short length of passage enters an immature stream that sumps 50m downstream and becomes too tight 100m upstream.

Extensions in Gorilla Walk?

Green Van Series, etc?

A dye test from Cueva de las Castañas (102) has been carried out and fluoroscein emerged between floor pebbles in Gorilla Walk opposite the entry of the last downstream inlet, but no dye was seen in the inlet water!

The Zoological Gardens leads off from the phreatic passages at the end of the Gorilla Walk as a wide, muddy crawl. The passage continues as a rocky rift with some very impressive fossil corals in the floor. There is one calcite formation or fossil which looks like the vertebrae of an animal about 30cm long. The passage ends at a calcite blockage and was surveyed for 265m in 1997.

Second River Inlet is 200m of mixed caving ending at a low crawl with a powerful draught. The link through into Cueva de Riaño (105) was made with the minimum of digging in 1986.

The next feeder is Gour Inlet which ends after 150m at a bouldery chamber and a climb which was bolted in 1993. The top and the observed large passage (with stal bosses and lots of mud) was not reached due to shattered rock on the chosen route. Another route may be possible and needs looking at.

By continuing downstream at Obvious Junction, Far Stomps is entered. This large passage runs for 550m over giant blocks to a sump - the water passing through to Sandy Junction. Near the start of this passage, a small inlet runs for 40m on the south side until it becomes too small where a false floor divides the passage.

Third River enters at the end of Crossover Crawl and is 800m of fairly unpleasant passage. After 200m upstream, a deep pool has to be negotiated followed by 300m of crawling and rift passage to where the water emerges from a sump. This point is about 50m from the downstream sump in Torcón de Riaño (106) although a human connection is unlikely. The rest of this uninspiring section of cave lies up on the right and ends at a couple of avens apparently over the top of the crawl traversed before.

Straw Inlet starts as walking passage but degenerates into a low crawl over mud. A passage near here was pushed during 1995 and ed the following year. The route draughts in well but goes up into a very slippery calcited boulder choke. Forging a way on would involve bolting and a major push.

Fourth River Inlet ends at a draughting boulder choke after about 200m. This has yet to be surveyed and pushed.

Eighty metres downstream from this point the entrance to the Astradome is seen on the left hand wall. A short walk up and along a muddy floored passage breaks out into a magnificent circular aven. Single voices sound like cathedral choirs as they rebound off the walls of this 30m diameter and 102.5m high feature.

In the summer of 1993 the Astradome was bolted up in about 10 hours over 2 days. The climb was stopped about 4m from the top by a bed of sandstone which would not take the studs. A hole in the roof was visible. In 1994, the climb was completed using a scaling pole. A chamber above was entered with passage above. It was from near the top of the Astradome that Alan Box fell to his death in that year. The passage 8m up was scaled into in 1995, but choked along the fault line in both directions. The climb was rigged from the base as 31.3m, 26.5m, 23.9m, 11.3m, 9.5m - that is 102.5m from the base to the lip.

95 Inlet can be entered on the right of the main river just after passing through 44 Chamber. Fifty metres in, an elliptical tube in the roof can be entered which leads to an increasingly muddy section of phreatic cave. The area appears flood-prone as a sump is bypassed via a muddy tube. The passage then slowly ascends to a 5m climb up to the boulders half way along Armageddon. This partial Armageddon Bypass is 500m long.

A small inlet on the right of Paisley Passage has been pushed for 250m to a large aven. The final small inlet of note is Shrimp Bone Inlet - the upstream continuation of the vadose rift passage that joins Duckhams Sump to Rocky Horror. The passage was explored for some 700m in the initial pushes. During Christmas 1989 the end was pushed for another 517m to a small, climbable aven. The end apparently lies under Sima del Escajadillo (088) although no sign of this (Spanish explored) pot can be found on the surface. During the Easter 2000 expedition, the aven was climbed for some 15m to a blockage with an inlet stream passage beyond. A subsequent trip removed the blockage and explored a further 300m.
The slot at the top of the pitch opens out almost immediately to an elongated, well decorated, oval chamber. Above and behind the slot at the top of the initial pitch the massive calcited boulder pile continues on up with several black spaces visible for 15m or so. Climbs up into this were too steep and slippery to consider with the gear available. At the opposite end, a 3m waterfall comes down off the edge of a 2m deep false floor only a couple of inches thick at it's outer edge. There is now a ladder hanging down this, initially awkward, obstacle.
The passage above is a slightly smaller version of Shrimpbone Inlet, being generally a joint controlled rift 1.5m - 2m high though in places the stream meanders turn this into a low tube / bedding. After 50m or so cross rifts are met which generally go a few metres to small avens (10 - 15m high?). There are some nice long straws in places. After approximately 150m a junction is met with a tall rift going right and left. Left, goes to a climb up and a tall aven. Right, goes through a calcited slot into a chamber at the base of several large dripping avens (20 - 30m maybe more), named Mongooses Don't Jump. The stream is not evident in this aven area, though whether it comes from water percolating through the sand and rocks at the base of the avens or from elsewhere is not clear. The last survey station in the terminal chamber is marked with a plastic novelty ice cream container.

***NOTE*** The next team in should take a sturdy new rope and possibly some climbing / rigging gear as the climbing rope may not last another party going up and down it.

Trident Passages, the major set of "side passages", and the ones which could provide a safe route through to Cueva de Carcavuezo (081) in Matienzo, have a length of 2.2km and are entered by climbing up calcite on the right after leaving the inlet at the start of Rocky Horror. At almost the highest point reached a clamber down over boulders to the right reaches a 31m diameter, smooth floored chamber. One outlet descends too tightly, but the main route is a clamber and walk to Mace Head Passage, of stooping dimensions and one of the better looking passages in Cueva de la Hoyuca. Large spiky crystals and calcite formations decorate the 1m diameter tube. Then the passage splits...........? More description needed.

Depths below the Matienzo hillside. Molephoning.

At Easter 95, Pull Up Passage was entered off Quadraphenia and was surveyed for 123m to a sump and narrow rifts.

During summer 2000, Wildlife Series was discovered through a hole at floor level at the start of Quadraphenia, 10m north of the tight squeeze. A crawl leads onto a 6m pitch into a streamway. Downstream, the passage becomes too low. Upstream, the passage splits with all branches choking except for one which turns west and links back to the chamber at the entrance. The passages are mainly stooping or crawling and were surveyed for 320m.

References: anon., 1974b (logbook); anon., 1974a; Fernández Gutiérrez J C, 1975; anon., 1975b (logbook); Kendal Caving Club and Manchester University Speleological Society, 1975 (survey and photo); anon., 1976 (logbook); Cope J et al, 1976 (survey); anon., 1977b (logbook); anon., 1978 (logbook); Corrin J et al, 1978 (survey and photo); anon., 1979 (logbook); Addis F et al, 1979; anon., 1980a (logbook); Corrin J et al, 1981b (survey and photo); Corrin J, 1980; Mills L D J, 1981; Manchester University Speleological Society, 1982 (survey and photo); Mills L D J and Waltham A C, 1981 (survey); Corrin J S and Smith P, 1981; anon., 1981 (logbook); Corrin J et al, 1981a; Corrin J, 1981; anon., 1982 (logbook); Corrin J, 1983c; anon., 1983b (logbook); Cawthorne B, 1984; Corrin J, 1983b (survey)/anon., 1984 (logbook); Barrington P and Hanson D, 1984; anon., 1985b (logbook); anon., 1986 (logbook); Corrin J, 1987 (survey); material in file; anon., 1987 (logbook); Corrin J and Knights S, 1988; anon., 1988 (logbook); Davis J and Corrin J, 1989; anon., 1989 (logbook); Smart C, 1990; anon., 1990b (logbook); anon., 1991 (logbook); Corrin J, 1992a (survey); Corrin J, 1992b (survey); Corrin J and Quin A, 1992 (survey); Corrin J, 1993 (survey); anon., 1993b (logbook); Quin A, 1993a; Smith P, 1993 (survey); Corrin J, 1994a; Corrin Juan, 1995b; anon., 1994a (Easter logbook); anon., 1994b (logbook); Neill A, 1994; Corrin J, 1994b (survey and photo); anon., 1995a (Easter logbook); anon., 1995c (logbook); Corrin Juan, 1995a; anon., 1996b (logbook); Corrin Juan, 1997a; Corrin Juan, 1997b; anon., 1997a (Easter logbook); anon., 1997b (logbook); Corrin Juan, 1998; Fernández Ortega F, Valls Uriol and Maria del Carmen, 1998 (photo); García José León, 1997 (survey and photo); Corrin Juan, 1997c; anon., 1999c (logbook); anon., 2000b (Easter logbook);
anon., 2000c (Summer logbook)
Entrance picture : yes
Underground picture(s): Quadraphenia 1 2   Small phreatic tube   Quadraphenia squeeze
Pig's Trotters Chamber  Pitch towards Flash Bulb Hall
Digital photos of the Wildlife Series by Juan Corrin. Click to enlarge.

Max Dobey in the Wildlife Series	Max Dobey in the Wildlife Series
pitch into the Wildlife Series	Ali Neill on the pitch into the Wildlife Series

Scanned slides from 1978 by Frank Addis. Click to enlarge.

Quadraphenia	Quadraphenia	Squeeze into Quadraphenia
Pigs' Trotters Chamber	Pigs' Trotters Chamber	Quadraphenia
Dyeing the stream near the Astradome	Astradome: setting up helium balloon	Astradome: setting up helium balloon.
Astradome: helium balloon	Astradome: thread pulled to fire flash gun	Astradome: 101.6m high
Astradome: helium voices

Digital photos of bolting in the 100m high Astradome by Alan Box. Click to enlarge.

Mark Wright bolting with scaling pole.

Mark Wright bolting with scaling pole.

Detailed Survey :
Line Survey: Four Valleys line survey. No detail.
On area survey :
Survex file :