Question about "the bends" From what I understand a SCUBA diver's breathing equipment will supply him with air at a pressure that correlates to the surrounding water (probably to make it easier for your chest to expand/contract naturally under high pressure water). The higher pressure air means more nitrogen gets dissolved in your blood. When you come up too fast you start breathing lower pressure air which makes room for the extra nitrogen to come bubbling out and cause all sorts of problems. That all makes sense except for the following which is copied from wikipedia's article on the bends: "DCS may be the cause of the disease called taravana by South Pacific island natives who for centuries have dived by breath-holding for food and pearls." http://en.wikipedia.org/wiki/Decompression_sickness If you are holding your breath then you aren't breathing in any high pressure air which means no extra absorbtion of nitrogen. How is it possible to get the bends if you take a deep breath at the surface, dive deep, then come back up quickly?