Nitrox Tables

Deeper? Longer? Better?

We have all heard the tune. We have all wondered at how weird it all sounded…especially since most of us nowadays have the Nitrox specialty which in fact teaches all scuba divers regardless of school or age that Nitrox is not deeper or longer and not necessarily better. Nitrox simply means an enriched oxygen mixture of Air and Nitrogen. Air is a form of NITROX with Oxygen being 21% of said mixture. When people speak of Nitrox they will also intermix the term Enriched Air, which is a more correct way of saying it. It means a gas mixture with more Oxygen than normal air and less Nitrogen. In Air, Nitrogen occupies 79% of the mix and the rest is Oxygen at 21%. Recreational Diving Nitrox Mixtures usually have Oxygen at 32% or 36% with Nitrogen at 68% and 64% respectively! You might have seen the stickers EAN32 or EAN36. Its shorthand for Enriched Air Nitrox and the Oxygen percentage the mix contains!

Taking the World By Storm!

Like everything else in the world things that are new are scorned for a while and then as if by magic will spread like wildfire. We are seeing the beginnings of this fire now as far as NITROX is concerned. There are stories which get more and more common as time goes by of outfits giving you NITROX filled tanks for free! That’s right. Free Air to dive with! Amazing? Think not. Great Marketing? Definitely!

Everything we are seeing happening now is geared towards bringing NITROX into the mainstream. Whether that is for the better…its anyone’s guess. Personally I would not dive on anything other than air as far as recreational diving goes…but, the going trend as things go is definitely a NITROX filled future, pan intended!

Main Benefits Diving NITROX

As you can imagine diving with oxygen enriched air mixtures has its benefits. In areas where recreational dive schedules are tight, with 3 or more dives a day for an extended period of time followed by air travel then this is where NITROX truly shines. Short, relatively shallower dives with Nitrox are safer when piled on top of each other during short blitz diving vacations as done by many in Sharm el-Sheikh! Why? Simple. Less nitrogen in your breathed mixture, less nitrogen on-gassing, better off-gassing using elective safety stop and ascend speed limits ensures smaller surface time intervals while preserving zero tolerance for residual blood nitrogen. As such you can dive more times at the expense of depth and time. Always remember that any dive profile is both a function of depth and time! Never one without the other!

In practice you can dive more times…have less surface time and still catch your flight (24-48h later) and remain at ease that you are safer than if you were diving with normal air mixtures! This is the essence of what Oxygen enriched air mixtures offer a recreational diver.

Nitrox Tank


Enriched Air has its darker side. That is to say that some knowledge of how gases interact with our bodies and correct procedures are necessary to ensure maximum safety! Always remember Nitrox means shallower dives! You might be thinking…why is it that I can’t dive deeper if I can now on-gas less nitrogen? Simple. Oxygen Toxicity! There is a limit to the partial pressure of oxygen our body can take. Its recommended no diver exceed 1.4 O2 Partial Pressure. If at surface on air with partial pressure of oxygen of 0.2 it will take 7 atmosphere depth to reach this 1.4 partial pressure of O2. It will never happen. Recreational depths and diving are restricted to 40m which while diving on air remain well below the 1.4 partial pressure of oxygen. Not so with Nitrox. Consider the 0.36 mix. At only 4 atmospheres it is an amazing 1.56! Four atmospheres we know to be 30m! Shallow is the word! You cannot dive Nitrox over the boundary of 20m -25m but you can have shorter surface time intervals and compete more dives in number during a given period of time.

Future of Diving?

With rebreathers maturing enough to be more and more easy to maintain and operate I think Nitrox is a temporary fix. The future of diving truly lies with rebreathers becoming reliable enough at low enough prices to be accessible to the mass of recreational divers out there, including yours truly! Taking that three hour dive will be truly an experience of a lifetime. Having all the time in the world to bask in the beauty of the deep and explore whole shorelines instead of a small part of a reef is what truly is worth waiting for on the other hand…a three hour dive could be boring for some people who love the idea of the ocean holding onto its riches for the next dive!

As always we will see. Let us know what you think!!!


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