Helium is also critical for scuba diving in the 200' to 1,000' depths. Currently, the most affordable, safest, and most common way to conduct these dives is wit

Helium is also critical for scuba diving in the 200' to 1,000' depths. Currently, the most affordable, safest, and most common way to conduct these dives is with open-circuit systems, where every breath is taken from the tank and exhausted into the sea where it bubbles away. A common mix is 21/35 (21% Oxygen, 35% Helium, the remainder almost entirely Nitrogen). Divers often use such mixes for dives in the 165 foot range. At that depth, a fit diver consumes a little over three cubic feet of gas per minute, which means that a little over one cubic foot of Helium is lost forever into the atmosphere each minute per diver. An alternative is a closed-circuit or rebreather system, where the exhaust gas is scrubbed of carbon dioxide and fresh oxygen added to replace the oxygen metabolized by the diver. Such systems are far more complicated, more expensive, and require much more training to dive safely. But one of the advantages of closed-circuit diving is that the inert gases (including Helium) are not exhausted with every breath. Therefore, it doesn't matter how many minutes a dive takes, Helium is not being exhausted into the water with every breath. This makes for a substantial savings in cost per dive and saves a non-renewable resource. As Helium prices rise, I hop there will be an economic incentive for divers to take up closed-circuit diving, which will in turn lead to the development of simpler, cheaper and safer systems.