Diving Future

Ultimate Diving Gas Mix

Quest for the Ultimate Gas

Every divers dream would be for a hazard-free gas mix with the benefits of air and with none of its limitations. Unlimited depth, no DCI/DCS, no Decompression, side effects and availability on the world market. Such a mix would easily become the holy grail of diving blends and its impact on the world diving industry would be immense.

The Riddle of Air

Nowadays almost all divers tend to breathe the tried and tested 'air' mix underwater - That is 21% Oxygen and 79% Nitrogen to those in the dark. Reliable and proven in diving, air is cheap and a compressor with happily fill the mix into dive cylinders with ease. Small wonder that its still being used to this day in countless diving operations. Unfortunately it has its limitations, a prime one being that the high nitrogen levels present in the mix can lead to symptoms of DCI (Decompression Illness), especially on dives where a fast ascent takes place. Even with a safe dive there is a remote chance of mild DCI symptoms developing. On the same note at depths beyond 40m narcosis levels can prove too much for safe diving due to the high amounts of nitrogen in the blend. Another side effect is the 'narcoleptic' after-affects of fatigue and sleepiness (One of the reasons many divers after the final dive are asleep!).

Nitrox & O2

There have already been several approaches to bridge the limitations of 'air' diving. A common one used is Enriched Air Nitrox more commonly known as EAN or just Nitrox. Nitrox blends vary but common mixes include EAN 32, EAN 36, EAN 40. The increased levels of oxygen and reduced nitrogen can greatly reduce the risk of DCI and extend dive time (gas supply permitting) also the greater margin of oxygen lessens nitrogen fatigue somewhat after the diving (it vary's according to mix!).

The use of pure oxygen for diving is practically unheard of in recreational but technical divers make use of it and benefit greatly from the nitrogen elimination in decompression. Pure oxygen is also used by military divers in operations as it causes no adverse fatigue, although excessive use will burn the lungs and airways.


A gas mix that extends depth considerably is Trimix. Consisting of oxygen, nitrogen and helium. Many divers consider trimix diving a 'black art' as they often misunderstand the way it 'works'. To put it simply the helium is added as a diluent for the nitrogen content and the oxygen level is also reduced (depending on the depth desired) with the lowered levels of nitrogen and oxygen the maximum safe depth can go to over 100m deep! The downside to trimix is that unless the oxygen content is kept between 18 - 21 % a travel gas is usually required for getting down to the safe breathing zone. The extra cylinder requirements and gas planning now take us into technical diving territory. A final threat is that it is an unforgiving gas and a mistake with it could be of grave consequences. Technical diving training is a pre-requisite to even take the trimix course (although some organisations accept nitrox) and the trimix gas itself can be expensive. Other known derivatives of this gas include heli-air and tri-air.

Overall the goal of greater depth is achieved but at the price of versatility and becoming complex hence its rarely seen for recreational diving yet the technical dive community is a keen user as are some country's navy's.


This blend of gas is perhaps the most powerful in terms of depth, heliox is a combination solely of helium and oxygen. Without any nitrogen present DCI is eliminated and depths of 300m and beyond can be achieved (dependant on blend used). So, is this the ultimate blend? Possibly, heliox is similar to the trimix shortcoming of a low oxygen content which, in the shallows is below what the human body can support. So a travel gas is essential. Helium is also a highly efficient conductor of heat and a diver breathing a helium blend will chill far quicker than an air breathing diver. Commercial divers are among the biggest underwater users of the mix. A final factor is that the price of helium is steadily becoming more expensive.

Overall though there is an almost tragic point to the gas. At present almost all the worlds entire helium reserves are in texas, USA and those reserves are running low. With helium shortages now just around the corner the use of heliox, trimix etc will soon become a thing of the past. The race is on to discover a new blend!

Hydrox (prototype mix)

If any blend comes closest to the perfect mix it is this one. Hydrox is the compelling blend of hydrogen and oxygen and its use so far has raised a few eyebrows (and possible singed a few!). Hydrogen is naturally occurring, easy to extract and cheap to 'produce'. Although still in the experimental stages the hydrox mix has produced good results. Fully breathable, No DCI, no side-effects and the gas conducts heat slowly (unlike Helium). Its only known flaw comes from the extremely volatile nature of hydrogen's 'infamous' flammability. While 100% O2 is also extremely flammable, hydrogen (see Hindenberg disaster) has a certain stigma attached to it that could scupper its chance of becoming the 'Ultimate Gas'.

Diving Lore's leading scientist believes with a closed-circuit rebreather system heliox is currently about as good as it gets. The gas Hydrox is, however still undergoing research and testing.

So with the Jury still out on Hydrox what is the Ultimate Diving Gas? The Diving Lore research team have gathered input from divers across the globe and the results have now been collated!

Having spent hours going over the figures we can announce that the Ultimate gas is currently... Heliox!

It should be realised however that despite the majority vote for Heliox many divers do realise that no matter how special or good a blend of gas is until a 'true' gas that does everything surfaces each blend ultimately suffers from limitations.

Perhaps there will never will be a gas that can shoulder the burden of the shallows, the deep depths and everything in-between while keeping a diver safe. It may be going a gas too far.

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