What Is Nitrox? Enriched Air Diving Explained
by Yannick Schroth
Jul 29, 2026
8 min read
Photo: Debal Das via Pexels (free licence).
This is general information, not a substitute for the nitrox course and proper training.
Key takeaways
- Nitrox = more oxygen (e.g. 32% or 36%) and less nitrogen than air.
- Main benefit: more no-deco bottom time at recreational depths.
- Does NOT let you dive deeper or use less gas (common myths).
- Shallower depth limit than air, due to oxygen toxicity.
- Needs a short certification; analyse every tank, set your computer.
What nitrox actually is
Nitrox, also called enriched air nitrox or EANx, is breathing gas with a higher percentage of oxygen than the air we normally breathe. Regular air is about 21% oxygen; common nitrox blends are 32% (EAN32) or 36% (EAN36). More oxygen means less nitrogen, and nitrogen is the gas that limits how long you can stay down before needing decompression.
The real benefit: more bottom time
Because you breathe less nitrogen, your body absorbs it more slowly, so you get more no-decompression time at typical recreational depths. On a single shallow dive the difference may be small, but across repetitive dives, multi-dive days and liveaboards it adds up to meaningfully more time underwater. Nitrox can also allow shorter surface intervals between dives, and some divers report less fatigue afterwards (though that benefit is debated and not proven).
Two big myths to kill
- Myth 1: "Nitrox lets you go deeper." The opposite. More oxygen means a shallower maximum depth, because oxygen becomes toxic at higher pressures. Each blend has a maximum operating depth you must not exceed.
- Myth 2: "Nitrox makes your gas last longer." No. You breathe the same volume; your air consumption is unchanged. Nitrox extends your no-deco time, not your gas supply.
The catch: oxygen toxicity and the depth limit
The trade-off for more oxygen is the risk of oxygen toxicity if you go too deep on a given blend. That is why nitrox has a maximum operating depth (shallower for richer mixes), and why the certification exists. In practice you must: analyse every tank yourself to confirm its oxygen percentage, work out the maximum depth for that mix, and set your dive computer to the correct mix. Never dive a tank you have not personally analysed.
Here are the numbers the article above deliberately did not hand-wave. The limit comes from partial pressure of oxygen, not from the percentage on the sticker: the deeper you go, the higher the pressure of every gas you breathe, and oxygen becomes the problem before nitrogen does. DAN states that "the recreational scuba community generally recommends a maximum oxygen partial pressure of 1.4 ATA". Applying that limit gives the working depths for the two blends you will actually be handed on a boat:
| Blend | Maximum operating depth at 1.4 ATA |
|---|---|
| EAN32 (32% oxygen) | 112 ft, about 34 m |
| EAN36 (36% oxygen) | 95 ft, about 29 m |
| Air (21% oxygen) | Deeper than either, which is the point: richer mixes are shallower |
DAN gives those depths in feet; the metric figures are converted and rounded, so treat them as approximate and use your computer and your analysis, not this table, on the day. You will also see 1.6 ATA quoted. DAN references it as a historical NOAA criterion rather than the everyday recreational working limit, and the practical reading is that 1.4 is what you plan to and 1.6 is a ceiling you do not treat as a target. Agencies and instructors differ in how they teach the margin between the two, so follow the standard you were actually trained under.
Do you need a certification?
Yes. Enriched Air Nitrox is a short specialty course (often a half-day to a day, sometimes with no dives required) from all the major agencies. It teaches how nitrox works, how to analyse a tank, how to find your maximum operating depth, and how to set your computer. It is one of the most popular and useful recreational specialties.
Is nitrox worth it for you?
- Worth it if: you do lots of dives (multi-dive days, liveaboards, dive-heavy trips), where the extra bottom time really pays off.
- Less needed if: you do occasional single, shallow dives, where the benefit is marginal.
For a nomad who dives a lot on trips, the nitrox specialty is often one of the best-value certifications to add after your open water course.
FAQ: nitrox / enriched air
What is nitrox in scuba diving?
Nitrox, also called enriched air nitrox or EANx, is breathing gas with a higher percentage of oxygen than normal air. Air is about 21% oxygen; common nitrox blends are 32% (EAN32) or 36% (EAN36). The higher oxygen means less nitrogen, which is what lets you extend your no-decompression time at recreational depths. You need a short certification to dive it, because it must be used within specific depth limits.
What are the benefits of diving nitrox?
The main benefit is more no-decompression bottom time at typical recreational depths, because you breathe less nitrogen, which is a real advantage on repetitive dives, liveaboards and multi-dive days. It can also allow shorter surface intervals between dives and, for some divers, less post-dive fatigue (though the fatigue benefit is debated). Nitrox does not let you dive deeper or use less gas; those are common misconceptions.
Does nitrox let you dive deeper?
No, the opposite. Because nitrox has more oxygen, it has a shallower maximum depth than air, not a deeper one, due to the risk of oxygen toxicity at higher pressures. Each blend has a maximum operating depth you must not exceed. Nitrox is about more time at recreational depths, not more depth. For going deeper you need different training and gases, not nitrox.
Is nitrox dangerous?
Used correctly, within its certification and depth limits, nitrox is safe and widely used. The key added risk is oxygen toxicity if you exceed the maximum operating depth for your blend, which is why nitrox has a shallower depth limit than air and why you must analyse every tank yourself and set your computer to the correct mix. The nitrox course teaches exactly this. Never dive a mix you have not personally analysed.
Do you need a certification to dive nitrox?
Yes. Enriched air nitrox is a short specialty certification (often a half-day to a day, sometimes with no dives required) offered by all the major agencies. It teaches you how nitrox works, how to analyse your tank's oxygen percentage, how to find your maximum operating depth, and how to set your dive computer. It is one of the most popular and useful recreational specialties, especially for people who dive a lot.
Yannick Schroth
Founder of NOMADREEF and a former digital nomad. This guide explains enriched air nitrox in plain terms; it is not a substitute for the nitrox certification and proper training, which teach you to analyse tanks and dive within safe limits. About the author · LinkedIn ↗
Sources
- DAN (Divers Alert Network), "Nitrox". The recreational working limit of 1.4 ATA partial pressure of oxygen; maximum operating depth of 112 ft for EAN32 and 95 ft for EAN36; and 1.6 ATA as a historical NOAA criterion rather than the everyday recreational limit. DAN, checked 7 August 2026. Metric conversions are ours and rounded.
- Enriched Air specialty training standards (PADI, SSI and equivalents) for the certification requirement, tank analysis and computer setup. Agencies differ in how they teach the margin between 1.4 and 1.6 ATA, so the standard you were trained under governs. Corrected 7 August 2026: an earlier version of this page referred to a maximum operating depth throughout without ever stating the partial-pressure limit it comes from or the resulting depths, and cited no agency source.
- Our own get scuba certified and travel dive computer guides.