Breath-hold diving (BHD) is both a recreational activity, performed by thousands of enthusiasts in Europe, and a high-performance competitive sport. Several “disciplines” exist, of which the “no-limits” category is the most spectacular: using a specially designed heavy “sled”, divers descend to extreme depths on a cable, and then re-ascend using an inflatable balloon, on a single breath. The current world record for un-assisted descent stands at more than 200 meters of depth. Equalising air pressure in the paranasal sinuses and middle ear cavities is a necessity during descent to avoid barotraumas. However, this requires active insufflations of precious air, which is thus unavailable in the pulmonary system. We describe a diver who, by training, is capable of allowing passive flooding of the sinuses and middle ear with (sea) water during descent, by suppressing protective (parasympathetic) reflexes during this process. Using this technique, he performed a series of extreme depth breath-hold dives in June 2005, descending to 209 meters of sea water on one breath of air.
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