Quote:
Originally Posted by ManicaMark
And Rob, you wouldn't get the bends, you only experience those when using a scuba tank with compressed air.
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That is incorrect. The trapped air he was breathing was compressed. At that depth and increased pressure (approximately 4 atm), a greater amount of gasses in the body are liquid - of particular interest is nitrogen. As you rise through the water column, the external pressure decreases and those liquid gasses begin to vaporize. Without decompression stops the body is unable to purge those gasses and you get bubbles of gasses forming in your joints (ie the bends), or worse, embolisms. Divers use decompression tables that take into account depth and time spent at those depths to calculate how long they will need to spend at each decompression stop. Since he was at 30m for 72 hours, he would be at significantly increased risk.
For these same reasons, divers should also schedule their dive trips to give time before flying.
Divers also exhale on their ascent as the air inside the lungs similarly expands. It's kind of neat actually, continuously exhaling a single breath on your ascent provided you were not deep enough long enough to require decompression stops.