Why do SCUBA divers use NITROX?

Why do SCUBA divers use NITROX?

Using NITROX (or enriched air as it is more properly known) allows divers to stay underwater longer and feel fresher after. NITROX allows this by reducing the Nitrogen and increasing the Oxygen content of the air in your tank.

You have entered the water for a SCUBA dive with your dive guide, they take you down into the deep, slowly moving down towards the bottom, your eyes are wide open at the abundance of sea life swimming by in every direction.

You follow your guide around under the water immensely enjoying the experience when all too quickly they signal to go up – your time has run out and you need to surface.

Your body cannot safely stay down any longer without repercussions. So up you go, slowly ascending wishing the whole time you could stay just a bit longer.

Have you ever wanted something you are enjoying or enjoy doing to last longer, make you feel less tired afterwards and have your body recover more quickly?

Of course, you have!

When we SCUBA dive, the pressure from the water exerts forces on our body that limits our time, but what if we told you that just by simply changing the percentages of gases we breathe can, we change that? Indeed the use of enriched Oxygen air or commonly called NITROX is a gas blend that divers use to do just that.

Provided you don’t breathe all your air too quickly, changing what we breathe can in fact allow us to stay down longer and recover faster – meaning you can have more time to look at the marine life.

There is quite a lot of physics and chemistry going on, but to be put more simply – the air we breathe is approx. 78% Nitrogen (N2), 21% Oxygen (O2) and the remainder small amounts of other inert gases such as Helium (He) and Argon (Ar).

When we SCUBA dive, the tanks are filled with this air directly so this is what we also breathe underwater. Our bodies don’t use N2 in any way, however, our bodies do maintain N2 dissolved in our tissues.

It’s the N2 that our bodies absorb more of when we dive as the water pressure pushes it into our tissues and it’s the N2 that sublimes back out again when the pressure is reduced.

Our bodies can take quite a lot of N2 and expel it out again with time to eventually return to normal. This takes an effect on the body and results in use feeling tired.

What NITROX does is increase the amount of O2 in the gas we breathe and reduce the amount of N2.

This simple change means we absorb less N2 underwater, meaning we can safely stay down longer and when we surface – there is less N2 to off-gas (get rid of) so we don’t feel as tired and can go back in the water quicker than normal.

Sounds like such a good thing, divers would do it all the time right?

Some do and when people go on extended diving trips like a week-long liveaboard, often NITROX is provided for free to give you more time underwater.

It is however not standard in everyday diving as the equipment and O2 needed are expensive, adding extra cost to the diver. Also if you are a new diver who breathes their air quickly – the effects of NITROX may be negated anyway so it’s not worth the extra cost.

NITROX can be any blend up to 40% O2 but is usually 32% or 36%. Your dive computer can change modes to reflect this very easily. There is an issue with Oxygen Toxicity which is why we don’t dive with just pure O2 and the upper amount is capped at 40%.

All SCUBA organizations like PADI or SSI offer NITROX or Enriched Air courses so any diver can move into different gas blends. Usually, the course is short and is all in the classroom getting to grips with some math equations, safety issues and other differences between air and NITROX.

The new blends don’t actually taste any different much to everyone’s disappointment, but you will be able to dive longer and feel better afterwards so if you haven’t gotten yourself qualified yet, it should be the first thing you do on your next dive holiday.

For any level of diver, NITROX will offer you more quality time doing the activity you love with no pills or chemicals, how good is that?

Scuba diving tanks on the boat with a sunset

Do technical divers use NITROX to go deeper?

Technical diving is where divers descend to depths far deeper and for far longer than recreational divers. While you might assume they do this with NITROX, you will be wrong.

While the same concept of reducing N2 is applied, O2 is not the primary replacement gas. This is because O2 under immense pressure can have major adverse effects on our bodies. Helium is used instead with different mixes at different depths.

Technical diving takes a lot of training and understanding to move into, but most dive shops around the world can point you in the right direction to get started if this is something you would like to learn.

Why do divers use Nitrogen?

This is actually a very common question, but the answer is quite simple – they don’t. The terms Nitrogen and NITROX are often confused. Divers are aiming to reduce their N2 load, not increase it. The NITROX term can be confusing which is why the term Enriched Air is used in conjunction.

Can you dive longer with NITROX?

Yes, you can, however if you are a quick breather underwater, then you won’t get much benefit. For those who breathe slower and more efficiently – your times can increase markedly underwater, up to 30% longer, though this depends on the actual mix you breathe and the depth you go to.

For a long journey type of dive where you follow a reef or around a large wreck and your dive is around the 20m mark – the extended time underwater makes the extra cost of NITROX definitely worth the while.

Don’t Forget Your Dive Insurance!

Before you go out on any dive trip or holiday, it is essential to make sure you have insurance that covers you if something goes wrong. Check out our dive insurance article for more information.

Or go straight to these dive insurance company websites:


Diver Alert Network (DAN)

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We all have fun things we like to do that we wish would last longer and SCUBA divers, can achieve this with a simple change in the percentages of O2 and N2 that they breathe.

If you are new to diving or are a seasoned pro – it’s totally worth gaining your Enriched Air certification before or during your next dive holiday as the benefits are all very positive without any side effects, allowing you to go longer and recover faster giving you more time under the water enjoying everything it has to offer.

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Paul Fulbrook

Paul Fulbrook is a writer, scuba diver, ex-science teacher and marine biologist. He has a passion for coral reef biology, diving on coral reefs and writing about diving. He also loves cats and his children (sometimes).

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