Does nitrox let you dive deeper?

No, the opposite. Nitrox has more oxygen than air, so oxygen toxicity limits kick in shallower. Its maximum operating depth (MOD) is shallower than air, not deeper. Nitrox is about time, not depth.

What is the main benefit of nitrox?

Less nitrogen. Because you breathe less nitrogen than on air, your tissues load slower, which gives longer no-stop limits at a given depth or shorter surface intervals between dives.

What is equivalent air depth (EAD)?

The depth at which breathing air would give the same nitrogen partial pressure as your nitrox mix at your actual depth. Because nitrox has less nitrogen, its EAD is shallower than your real depth, which is why it allows longer no-stop times.

Does nitrox reduce fatigue?

Many divers report feeling less tired, but there is no strong scientific evidence that nitrox reduces fatigue on its own. The proven benefit is reduced nitrogen loading.

Dive theory, decoded

Nitrox (Enriched Air) Explained

Nitrox is one of the most misunderstood topics on the theory exam, mostly because people think it is about going deeper. It is the opposite. Here is what it actually does, and where its limits are.

What nitrox is

Nitrox, also called enriched air or EANx, is just air with more oxygen and therefore less nitrogen. Regular air is about 21% oxygen. Common nitrox mixes are EAN32 (32% oxygen) and EAN36 (36% oxygen). The number is the oxygen percentage; the rest is nitrogen.

Why divers use it: less nitrogen, more time

The whole point is the nitrogen you are not breathing. Less nitrogen in the mix means your tissues load nitrogen more slowly at a given depth (Henry's law). That buys you one of two things:

Longer no-stop time at the same depth, or
Shorter surface intervals between repetitive dives.

That is the real, proven benefit. Nitrox is a time advantage, not a depth advantage.

The myth that fails people: "nitrox lets you go deeper." Wrong, and dangerously so. More oxygen means oxygen toxicity becomes the limit sooner, so nitrox has a shallower maximum operating depth than air.

The limit: oxygen and MOD

More oxygen is not free. Past a certain partial pressure of oxygen, you risk central nervous system oxygen toxicity. That sets your maximum operating depth (MOD), and for nitrox it is shallower than air. EAN32 at a 1.4 PO2 limit maxes out around 33 metres; air does not hit that oxygen limit until far deeper. So richer mix, more bottom time, less depth.

Equivalent air depth (EAD)

EAD = ( (1 − FO₂) × (depth + 10) / 0.79 ) − 10

EAD answers "how much nitrogen am I really getting?" It is the depth at which plain air would give the same nitrogen partial pressure as your nitrox at your actual depth. Because nitrox carries less nitrogen, the EAD is always shallower than your real depth, and that shallower number is what drives your longer no-stop limits. EAN36 at 30 metres has an EAD of roughly 22 metres.

What you actually have to do

Nitrox requires its own certification. Before every nitrox dive you personally analyse the tank, confirm the oxygen percentage, set your computer to that mix, and label the cylinder with the mix and its MOD. The exam expects you to know both the why and this procedure.

Test yourself, then go deeper

Try the free practice quiz, or get the full guide with all seven theory areas and a 60-question exam.

Free practice quiz Get the guide ($29)

Frequently asked questions

Is nitrox worth it?

For repetitive diving (liveaboards, multiple dives a day), yes, the extra no-stop time and shorter surface intervals add up. For a single shallow dive, the benefit is small.

Can you dive nitrox on air tables or an air computer?

You can dive nitrox using air limits and it is conservative (safer), but you lose the time benefit. To gain the benefit you use nitrox tables or set your computer to the mix. You must still respect the mix's MOD regardless.

What mixes are most common?

EAN32 and EAN36 are the two standard recreational mixes. Technical divers use a wider range, including higher-oxygen mixes for decompression.

Independent study aid for exam preparation only. Not affiliated with or endorsed by any certification agency, and not a substitute for certified nitrox training. Always analyse your own gas and dive within your training.