SCUBA is probably...
...one of the most underestimated risk sports one can pursue. There are thousands of certified divers descending under the water's surface daily. On average, depth is <40ft, duration is less than 30 min and typically, folks dive no more than once per day. Under these circumstances, there's rarely a problem. The risk increases when one becomes more active. One of the most common risks is the danger of Decompression Sickness (DCS) also know as "the bends". While diving, the pressure underwater causes nitrogen from the air a diver is breathing to dissolve into their body. The amount of nitrogen absorbed depends on the depth and the amount of time spent underwater. If a diver spends too much time underwater and ascends rapidly to the surface, the nitrogen may not dispel properly. If the nitrogen gases remain inside the body, DCS can result in terrible injuries including death, blindness and paralysis.To manage DCS, there are two popular dive tables, one provided by NAUI, the other from the US Navy which, when understood and used properly, can provide the proper depth, dive period, decompression stops and between dive intervals guidelines.For example, a diver executes a dive to 50' and stayed down for 35 minutes. How much nitrogen would the diver have in their body from that dive period? How long a period should this diver wait on the surface between dives to ensure adequate nitrogen dissipation?If these risks were nonexistent, why are most divers asked to sign liability waivers and releases from the certifying agent, dive resort, boat operator, and others related to a dive. The Diving Accident Network (DAN) reports that, in the US, slightly less than 1,000 divers are treated for DCS each year. About 10% die from DCS each year. Over 1/2 of those are divers did not exceed their dive limits on a dive table or computer! Typical driver training courses span 3-8 days and doesn’t require any equipment assembly or sharing, complex statistical table computations or an understanding of one’s respiratory system behavior. Although statistically a safe sport, prudence dictates that the more one knows and understands, the less risk and more fun the result of the training will be. Take the time, study and prepare for the unexpected.BTW- equipment case in point; rented tanks and a weight belt from AquaVenture in Tortola BVI. Just after passing 25 ft, the clasp/buckle of my buddy’s weight belt came undone, dropped to the bottom, and he ascended out of control like a balloon. Had he been at 60’ near the end of his dive this could have had a different ending. Upon inspection by the dive shop, a pin across the clasp had a slight bend, which reduced the holding force needed to keep the buckle closed. I use weights integrated into pockets on my BC.