OUCC Proceedings 12 (1986)

Cave Diving in the Picos de Cornion:

Potential and Preliminary Exploration

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by C.J. "Dani" Danilewicz


During 1984, at a meeting of the Expedition Committee, a proposal to include diving in the 1985 expedition was defeated. The main reasons given were that the Club had no specific diving permit and that pushing more than one location would divide the expedition. The latter objection is perhaps rather fatuous, as on most OUCC expeditions work goes on at more than one site. The former is also rather contentious, as diving may be regarded as just another tool in cave exploration. With these considerations in mind, and also mindful of the Club's position with the Spanish authorities, an independant eight-strong reconaissance expedition to the area was organised in June 1985.

The expedition was entirely self-financed. Our aim was to look at several sumps and to assess the potential for a future major expedition. The sites chosen were: Cueva Trumbio (Collis, 1975a); Cueva el Gueya Reinazo (Collis, 1975b); El Hoyo la Madre (Fowler and Laverty, 1979); and Cueva del Osu (Fowler and Laverty, 1979; Gale, 1984a). The main reason for the selection of these caves was their proximity either to Los Lagos or the Los Lagos - Covadonga road. With only five days available, it was essential to put in the maximum time underground and to minimise travelling time.

Cueva Trumbio and Cueva el Gueya Reinazo

These two caves were linked hydrologically by the French group Speleo-Club Alpin Languedocien in 1964 (Collis 1975b; Gale, 1984b). Each cave was visited twice during the expedition. On 26 June, two divers explored the terminal sump of Gueya Reinazo, the second passing the sump to an airspace after 30m. The airspace consisted of a 1m square, 0.25m high airbell, with a boulder roof and a stream entering through a boulder wall. There was no way on without digging; under the circumstances this was inadvisable. A return visit was made on 30 June by two divers, but they failed to make any further progress. A return in the future would need to be made with equipment which would allow the boulders above the airbell to be dislodged from a safe distance.

Cueva Trumbio was visited on June 27 and 28. Although Jim Sheppard (pers. comm.) had doubted whether the terminal sump was divable, we found it to be large and quite clear. On June 28, therefore, a large carry of tackle was arranged and a diver put in the sump. After several minutes he returned and described the sump as being 5m deep, 6m long and descending in steps under a boulder roof. The diver stopped at a point where the sump dropped down through a narrow slot. Although the slot may be negotiable after de-kitting, any disturbance of the overlying boulder roof would have dire consequences. For this reason, the sump was left until some form of shoring could be introduced. A second diver confirmed the layout of the sump. In addition to the sump, several massive roof tubes were noted on the way out and a little bolting may lead to a sump bypass.

El Hoyo la Madre

Of all the caves visited this would seem to have the greatest potential for cave diving. It is a major resurgence with an undefined catchment area and no proven feeders. None of the expedition had visited this cave before and the first attempt to find it, on June 27, failed due to the usual atrocious weather. On June 29, four members set off in glorious sunshine and had no navigational problems. The walk should not, however, be taken lightly. Sufficient equipment was carried to equip one diver. The cave itself was not difficult once the 20m climb to the entrance had been overcome. Rapid progress was made to an incredibly clear upstream terminal sump (Sump II). The diver passed this sump and emerged after 100m in a pool 20m long and 4m wide. At its far end, a 2m wide stream entered on the right. The diver dekitted and followed this streamway until it closed down after 20m. Near this point, the entire stream entered down a 4m high waterfall in the left wall. After six attempts, the diver scaled the waterfall and followed a further 10m of deep water streamway which ended at a sump. The prospects for extension remain very good.

Cueva del Osu osu.gif (3918 bytes)

A total of three pushing trips was made to Osu. The entrance series was rigged immediately upon our arrival on June 25 and the first pushing trip was made on June 26. Sufficient equipment for two divers was portered to the downstream sump by a party of five in a four hour struggle. The first diver passed the sump after a dive of only 4m. Both divers then explored downstream whilst the three porters tried to find a sump bypass. The extension consisted of approximately 40m of easy streamway in a tall rift (Buccaneer Streamway) which ends abruptly at a stal blockage, called Potter's Bar in memory of Keith Potter. This was scaled and beyond a large chamber was entered. Several ways radiated from this chamber which was, therefore, named Oxford Circus. The most obvious way on was a large, clear sump at the far end. This was not dived on this occasion. A steep ramp beyond the sump pool was gained but could not be climbed due to a combination of its steepness and its muddiness. Several other ways, all climbs, were investigated but all became too exposed for unequipped climbing. The divers, therefore, returned and rejoined the porters. On the way out a number of avens were scaled to heights of over 20m, but in every case the climbs became too exposed.

On June 29, two divers carried in some additional gear and attempted the second sump. This dropped in a shaft 3-4m in diameter. However, visibility was extremely poor and at -9m the first diver found himself over-weight and, therefore, exited. Both divers then made their way back, carrying a large quantity of gear as far as Camp Chamber.

The final Osu trip was on June 30, when a five man group all passed the first sump and a diver was kitted up and put in the second sump. He descended to -17m in zero visibility. Not being able to see, he returned and detackling began. A total of fifteen assorted bags, bottles and boxes were finally pulled out of the cave after a nine hour detackling trip.

The first sump in Osu is only 2m long and easily free-dived. On a return visit it is essential that an equipped diver is put into Sump II immediately on arrival before visibility is lost due to silt being washed in from a disturbed Sump I. Several climbs, both before and after Sump I, may also prove fruitful.


Although only four caves were visited, a total of three sumps were passed and there is still scope for extension in all four caves. Without doubt, El Hoyo La Madre and Culiembro will probably provide the best returns. In both cases diving conditions, apart from temperature, are ideal and their potential is enormous. These preliminary investigations indicate that diving should become a regular and accepted part of any future expedition, provided that the divers are well trained and do not divert effort from other projects. This expedition demonstrated conclusively that a small group of divers can be entirely self-sufficient for their portering and rigging needs. It is to be hoped that in the future the Club will benefit from the work of divers, not only by their explorations but also by the increased knowledge of hydrology and structure that their work can reveal.


I should like to thank the following cavers who made up this expedition: Dave Francis (LUCC), Stuart Gillet (ASS), Pete Riley (NPC), Rick Stanton (LUCC), Barry Sudell (NPC), Mike Thomas and Angela Timms (MTCPC). Also J. Harris (Motor Bodies) Ltd. of Barnsley for their discount rates for the hire of the expedition mini-bus and roof rack.