For deep-diving mixed-gas divers, it's far worse. Routinely diving below 130 ft (40 m), the divers are always in pitch darkness, relying on work and helmet lights, and they are tethered to the ...

Despite rumors that deep-sea dives shorten lifespans and that there aren't divers past the age of 35, Callahan says he works with everyone from 18 to 65. A large part of why they can dive for so ...