Helium Is Now Harder to Get

If you suffer from nitrogen narcosis, breathing trimix might be the answer. Some training agencies, such as Global Underwater Explorers, suggest that any diver going deeper than 100 feet should be using trimix instead of nitrox or even plain air -- that's because reducing the amount of nitrogen and oxygen in the mix decreases your likelihood of nitrogen narcosis while avoiding oxygen toxicity.

If you read the travel articles about Truk in Undercurrent's last two issues, you'll remember our wreck-diving writer reckoned her recall of what she saw at depth then was better than during a previous visit when she used air, even though most of her wreck divers were not that deep. The amount of helium in the mix is varied according to the depth to which a diver intends to go. Technical divers use a mix that is hypoxic (in the shallows) for the deepest parts of their dives.

That's all well and good, but the third gas in a trimix is helium, and it comes with two penalties. First, there's the increased decompression time, because helium is absorbed quicker by human tissues but comes out of solution slower than nitrogen. Ignoring the helium penalty comes at a cost, as many bent technical divers will tell you.

The second snag is a recent, and expensive, one. There's a world shortage of helium. Besides party balloons (this shortage has freaked out florists and party throwers), helium is used in airbags, scientific research, cryogenics, weather balloons, rocket fuel, and, ironically or not, hospitals' MRI machines. Helium is the second-most abundant element on Earth, but taking it out of the ground and storing it, because of its light weight, is costly. Once there's more helium in reserve, costs could go down, but like any natural resource, prices will fluctuate depending on demand and supply. Either way, its use for scuba diving is pretty low down on the list of global priorities, so don't expect an immediate price drop.