Nitrox is the certification everyone recommends and nobody quite explains. You finish Open Water, and within about five minutes someone — an instructor, a dive buddy, a stranger on a boat — tells you the next thing you should do is get your nitrox card. Usually with a vague promise about “longer dives” attached.
They’re not wrong, exactly. But nitrox isn’t magic, it isn’t right for every dive, and it definitely doesn’t do some of the things people think it does. So here’s the plain-English version: what enriched air actually is, what it genuinely does for you, and whether the course is worth your time and money.
What nitrox actually is
The air you normally breathe is roughly 21% oxygen and 79% nitrogen. Enriched air nitrox — often labelled EAN32 or EAN36 — simply has more oxygen and correspondingly less nitrogen. EAN32 is 32% oxygen, EAN36 is 36%, and so on.
That’s the whole trick. More oxygen, less nitrogen. Everything nitrox does — the good and the limits — flows from that one change.
What it genuinely does for you
More bottom time (sometimes a lot more)
The main event. The thing that limits how long you can stay at recreational depths isn’t usually your air supply — it’s nitrogen loading. Nitrogen is what drives your no-decompression limit. Breathe a gas with less nitrogen in it, and you absorb nitrogen more slowly, which extends how long you can stay down before hitting that limit.
On a shallower repetitive dive, the difference can be substantial. A second or third dive of the day, where nitrogen from earlier dives is already eating into your limits, is where nitrox really earns its keep — you get meaningfully more time in the water. For a diver doing multiple dives a day on a trip, that adds up to a lot more diving over a week.
Less fatigue (for a lot of divers)
This one is more subjective, but it’s widely reported: many divers feel less worn out after a day of diving on nitrox than on air. The science here is debated and the effect isn’t universal, so we’ll be honest and call it what it is — a lot of people feel better, some feel no difference, and it’s a nice bonus rather than a guaranteed outcome.
What nitrox does NOT do
This is where the myths live, so let’s clear them out.
It does not let you go deeper. This is the big misconception, and it’s actually backwards. Because nitrox has more oxygen, and oxygen becomes toxic at high partial pressures, enriched air has a shallower maximum operating depth than regular air, not a deeper one. The more oxygen in the mix, the shallower your depth limit. Nitrox is a tool for staying longer in the shallower-to-moderate range, not for going deep.
It does not save you air. You breathe a nitrox tank down at exactly the same rate as an air tank. Your gas lasts no longer. What lasts longer is your no-decompression time, which is a different thing entirely. If you’re the diver who always surfaces low on gas, nitrox won’t fix that — better breathing habits will.
It is not more dangerous, but it demands more attention. Nitrox introduces one new hazard to manage: oxygen toxicity if you exceed the mix’s depth limit. The course exists largely to teach you to analyse your gas, set your computer correctly, and respect your maximum operating depth. Done properly, it’s completely safe. It just asks a little more discipline than air.
So should you get certified?
Here’s an honest way to decide.
Get nitrox certified if you do multiple dives a day, take dive trips or liveaboards, dive in the shallower-to-moderate range where nitrox shines, or you’re someone who feels wiped out after a big day of diving. For these divers — which is most divers who dive regularly — it’s one of the best-value cards you can hold. The course is short, and it opens up more diving on every trip you take.
You can happily wait if you’re an occasional single-dive diver, or your diving is mostly deep, where nitrox’s depth limits work against you. It’ll still be there when your diving changes.
For the great majority of recreational divers, the honest answer is yes, and sooner rather than later — because every trip you take without it is a trip where you left bottom time in the tank.
Getting it done
The nitrox course is one of the quickest certifications in diving — largely knowledge-based, focused on understanding the gas, analysing your fills, and setting your computer. Many divers knock it out fast and put it straight to use on their next trip. If you’re heading somewhere with multiple dives a day coming up, this is the card to get before you go.
Have a look at our continuing education options, or come talk to us about timing it around your next trip. And if you want to understand the full world of dive gases beyond enriched air, that’s a longer and genuinely fascinating conversation we’re always happy to have.
Nitrox won’t turn you into a different diver. It’ll just quietly give you more time doing the diving you already love, and for most people, that’s more than enough reason.