OUCC Proceedings 6 (1974)
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As the expedition contained only one trained cave diver, equipment requirements were small. Two high pressure Draeger 43 cu. ft. cylinders and one Sealion 40 cu. ft. were taken, with a Deepstar demand valve and a Snark II as a reserve. 300 ft and 500 ft reels of 0.5 in. circ. Courlene, the usual gauges, accessories and spares completed the kit.
It had been intended to obtain air from a miniature compressor giving 1300 p.s.i. and powered by a 27 V 21A electric motor running from two car batteries. This proved impossible as adequate filters had not been obtained in time. Cylinders were therefore carried out fully charged, in calculated ignorance of ferry and customs regulations, although we were prepared if necessary to blow off the air and have the cylinders charged at Santander.
A communication from the Federacion Cantabra de Activid ades Subacuationes, Jesus de Monasterio, 20, Santander, mentions charging facilities at Compania Espanola de Oxigeno, Calle Emilio Pino No. 4, Santander; Club 0.1.5., Jardines de Pereda, s/n, Santander; and at Club G.E.A.S. de Aviles. Llaranes, Aviles. All were over 100 kilometres from the expeditions base. I believe that air may also be obtained near Bilbao the above organisation should be able to confirm this. I can give no guarantee of the purity of the air from any of these sources!
The active nature of most caves in the Sierra de Cuera has been described elsewhere. Progress along stream passages tends to be terminated by sumps rather than other obstructions. There are diving sites in Bolugo, La Boriza, Ojo del Rio Bolugas, Cueva a Sul, Calduenin, Cortines, Cueva de la Llera, and at Buda and La Borbolla. From the point of view of this expedition, the most interesting sites were La Boriza, Calduenin, and Ojo del Rio Bolugas. In la Boriza, the steep streamway profile and the abundance of high level routes elsewhere |l the cave had raised hopes of a relatively short sump, perhaps with a by-pass. We had heard that the lake in Calduenin dried out in drought, giving access to several kilometres of passage. The sump at the Ojo del Rio was known to be short since running water could be heard through a narrow crack only a few yards away.
The upstream sump of La Boriza (sump 2) was dived on July 10th, on a chilling trip when maypoles were also carried as far as Celtas Corner. The dive is straightforward, in superbly clear water and a passage some 3 metres square. A passage running off to the left closes down after 3 metres; this passage was noticed when free diving in 1970 and was then thought to be the main route. The sump is about 17 metres long and a line was left through. There is a convenient platform just beyond the sump, but Boriza 3 consists only of 30 metres of deep canal, leading almost certainly to another sump, though the last few feet of duck were not closely examined.
Calduenin cave was dived on July 14th, when the downstream sump was visited first. Although this appears to be constricted, the steep gradient of the shingle bank above it and the lack of foam on the water suggests that it is usually little more than a duck. The floor hand side for 20 metres, then crossing to the left and ascending. The two branches of this cave are thought to come from the Cueva a Sul and Torcona del Valle respectively.
Many sumps remain to be dived. However, the most rewarding sites are likely
to be those already visited, with the addition of the
Cortines sumps. There is
scope in the area for both relatively short diving searching for the links
between Callau Roviera, Cueva a Sul and the Ojo del Rio - and also for exploring
the longer sumps which may exist behind Calduenin and Cortines
A party of two or more divers could explore further upstream in La Boriza or downstream in Calduenin; both of these may reveal extensive 'dry' passages.
The 1970 Nottingham University expedition, under James Cobbett, has dived a number of sites to the south and west of the Sierra de Cuera. A report appears in C.D.G. Newsletter No. 18 (Jan 1971). Reports on the dives described above appear in C.D.G. Newsletter No. 21 (Oct. 1971).