12MB PDF - Association for Mexican Cave Studies

Aerial view of Nacimiento del R10 Mante, Tamaulipas.(William Russell)plunge downward at least 9 metersdeeper, making the vertical extentof the pit itself on the order of102 meters as measured from the roofabove it at a depth of 8 meters.*We dubbed it Macho Pit, thinking itironic that, in this land of drypits more than 4 times as deep, thisrelatively (as far as we know, sincewe never saw bottom) shallow pit maybe the most difficult to bottom!Perhaps Frank, who has done somemixed gas cave diving in the Ozarks,will return someday and do the trick.Nacimiento Media LunaEven though we were trying to rotatethe first dives at each site todifferent people to keep everyone happy,no one seemed to be interested indiving the night we arrived at MediaLuna, so Dan, Paul and I found ourselvesmaking dive #10 here. The watertemperature was quite comfortable,28°C at the surface and 30°C below at adepth of 30 meters, and visibilityapproached 30 meters of open water atthe largest of the 6 spring vents locatedtherein. Unfortunately, theonly cave located - the main spring ­was small and short. extending to adepth of 48 meters before the strong*Ed. Note: Interestingly, this total depth of 110 meters puts it 20 metersbelow sea level, as the elevation of the surface of the spring 1S 90 meters asl.25