Dr. Bill Stone just forwarded me photos of the new Poseidon rebreather that is now being shipped out of Sweden. The Cis Lunar MK6 unit will be utilized in exploration this winter in Mexico.
The J2 Expedition will explore one of the world's deepest cave systems, reaching a depth of 1210 meters (4,000 feet) at a distance of more than 8 kilometers (5 miles)from the nearest entrance. Explorers attempting to establish a new record for the deepest cave on earth in 2006 encountered a series of underwater tunnels at the bottom. A reconnaissance dive revealed the presence of three unexplored water filled passages. The lead diver, using carbon-epoxy open circuit diving equipment running at 340 bar (5,000 psi) pressure was able to pass the first two underwater tunnels whereupon he discovered an 80 meter (250 foot) diameter cathedral size chamber. At the lower end of the chamber the tunnel continues, but underwater. Stone developed the next phase of his series of Cis Lunar rebreathers to crack this sump.
The rebreather itself has two 2 liter (13 cft) tanks onboard. Sidemounted high pressure carbon epoxy tanks will be worn as bailout gas. Stone expects that the shallow sump will quickly yield new open-air passage. Although his rebreather is designed for recreational diving, it will allow the team an additional margin of safety and less reliance on transporting open circuit tanks topside for refills.
The sump team will begin training in Austin, Texas this October. The expedition itself will being in February and run for three months. -- Jill Heinerth