12MB PDF - Association for Mexican Cave Studies

Entrance chamber, Nacimiento del Rlo Choy.(Bill Stone)meters long by 5 ffi2ters wide with aconstant 6 meters or so of air aboveus. No air-filled leads were visible,so we tied off at 267 meters penetrationand ~eaded out.The follo..,ing day the th'.:"el~ ofus decided to run a new line alongthe top of the canyon, both to conserveair and to check for any moreair spaces that might be located a­long the way. Things got off to a~ad start when Dan, wearing twinlOa's (which weigh over 100 lh8.),took~ a tumble while climbing the2-3 meter falls in the run belowthe headpool, slightly injuring onearm. Fortunately, he felt good e­nough to dive after a brief rest.Despite our intention to stayshallow, we had to descend -to adepth of 24 meters near the entranceto find a route large enough to comfortablyswim through, but thereafternever had to c1esceEd below adepth of 12 meters. MeamJ:,ile, wefound five more large air spaces onthe way to the one we had discoveredthe previous day. We also found thatthe previously discovered sixth airspace was much latger than we hadpreviously supposed, most of its 90meter length hidden by an offsetjust past where we had stopped theday before. At the end of the airspace we dropped all the way to 40meters before finding a way on,t~ough on the ascent from t~at depthit appeared that a shallower routemight exist along the left wall. Thetieoff at 379 meters represented themaximum penetration that was attainedon t}-le trip.Even though it cost us a greatdeal of added decompression time, weelected to take a deep route out29