Fou de Bor (Previous Exploration by X.Garza 1986, 1997)

11/10/10 With help from David and Nuria Magdelenea 2 x 12ltrs, 3 x Ali80, two rebreathers, and diving kit for Artur Kozlowski and Chris Jewell were moved into the cave. Each diver would take one cylinder of trimix (15/50) and one of air and an Ali80 of O2 was also left at 6m. This cylinder was also equipped with hoses for adding extra O2 to the rebreathers for the long decompression. Chris used his chestmounted rebreather and Artur a Megaladon.

It had been raining recently but the water resurging outside the cave appeared clear when the team went underground. The carry underground was short but several trips were required and it was some time until everything was inplace at the sump. Eventually Chris and Artur dived at 5.30pm. The sump pool was static and murky after the kitting up process but the divers expected to encounter good visibility later. At the first underwater squeeze the strong flow of the underground river was met...

...but rather than bringing clear water and good visibility instead it was milky with about 1m visibility. The flow of the water was also very strong and at -23m Chris called the dive. Easy with the chestmounted rebreather, the squeezes gave Artur and his backmounted unit some more difficulties but eventually he found the right spot and the pair surfaced after just 13minutes.

 
13/10/10 Conditions above ground had improved slightly but the divers were not optimistic of good conditions underwater. However when the team reached the sump pool they could see that the water was 1m lower than on the previous visit.

Once in the water, a -9m the fast flowing river was met and the pair emerged out of the gloom into clear(ish) water with probably 5m visibility. The old line was followed down to the -40m point indicated on the survey and here a second line appeared next to the first. Also rather than carry on directly to 60m as had been reported, at 50m depth an elbow was passed and the line was followed up to -30m. Shortly after, back down at 40m loose old line was encountered and tidied up before the divers tied on their own reel and set off. Almost immediately a deep shaft was encountered taking them down to 60m before the gradient eased off. Following the sloping passage 80m depth was reached before the cave started to rise in a series of steep steps. The passage was large here and the divers rose up above boulders in the steeply ascending cave. At 35m depth after laying 210m of new line and having 100minutes of decompression already racked up Chris and Artur turned for surface.
A problem with his chestmounted rebreather meant Chris used open circuit air for 15minutes at -9m before swapping back to the rebreather to complete the decompression. The 9m stop was made halfway through the squeeze, with the divers feet in clear fast flowing water and their torsos and heads in the murky static part. At -6m the visibility was 30cm and an extremely cold 110minutes was spent in the 8 degree water leading to a total dive time of 5hours. The end of the line is now approximately 588m from base.