Loading the latest software revision in the Mk6 rebreathers at base camp.
[photo ©2009 US Deep Caving Team]

Multi-rebelay pitch at -580m in polished, banded rock strata.
[photo ©2009 US Deep Caving Team]

Swimming the canals beyond Surprise Sump.
[photo ©2009 US Deep Caving Team]

Panoramic view of Camp 2A at -800m.
[photo ©2009 US Deep Caving Team]

The "moustache" of Chapulapa, at -840m.
[photo ©2009 US Deep Caving Team]

Reassembling Mk6 rebreathers at the staging area 20m above Sump 2, at the -1,200m level of J2.
[photo ©2009 US Deep Caving Team]

View of Sump 2 and the dive deck from 20m above.
[photo ©2009 US Deep Caving Team]

Kitting up on the dive deck at Sump 2.
[photo ©2009 US Deep Caving Team]

The return dive through 220-meter-long Sump 2 with two 55-liter packs of equipment. Lead and rocks were used to ballast the packs so that they were approximately neutrally buoyant underwater.
[photo ©2009 US Deep Caving Team]

At Camp 4 during the final 19 day push beyond Sump 2.
[photo ©2009 US Deep Caving Team]

Sump 4 has now been explored in two different tunnels to 170 meters and 350 meters penetration, respectively. The main tunnel averages 8 to 10 meters wide by 5 to 8 meters tall. It continues at 350 meters penetration and appears to be rising. The direction of the tunnel - almost due west towards Cueva Cheve - confused the early exploration efforts. It now promises a potentially quick connection to the main subterranean Cheve river.
[photo ©2009 US Deep Caving Team]