/sci/ - Science & Math

>Had he been wearing standard scuba gear, Pipin could descend to about 350 feet before suffering "rapture of the deep," a narcotic like stupor caused by compressed nitrogen. If Pipin worked for a commercial diving outfit that serviced oil rigs, he'd spend weeks in pressurized nodules so he could work at a depth of 1,000 feet. Some test dives using oxygen mixed with various exotic gases have enabled people to survive at 2,400 feet, but that seems about the limit for unprotected humans.
Could anyone explain why there is a 'limit' there? Why can't you just reduce the oxygen content of the helium-oxygen mixture and dive to the bottom of the Marianas trench?