What Is Nitrox? A Beginner's Guide to Enriched Air Nitrox
Updated: Oct 10
If you have spent any time scuba diving, you have probably heard divers talk about Nitrox.
You may have seen tanks marked “Nitrox,” heard someone say they were “diving 32,” or noticed that a dive boat offers Nitrox as an alternative to regular air.
But what exactly is Nitrox?
Why do divers use it? Is it safer than regular air? Does it really allow you to stay underwater longer? And do you need a special certification to use it?
The short answer is that Nitrox is a breathing gas containing more oxygen and less nitrogen than ordinary air. The most common recreational blend is Enriched Air Nitrox 32 (EAN32), which contains 32% oxygen.
For recreational divers who make multiple dives during a day, Nitrox can be a very useful tool. And because the SSI Enriched Air Nitrox 32 course can be completed online, getting certified is easier than ever. Let's take a closer look.
What Exactly Is Nitrox?
The word Nitrox is a combination of “nitrogen” and “oxygen.” Technically, Nitrox can refer to almost any breathing gas made primarily from nitrogen and oxygen. In recreational scuba diving, however, the term is generally used for Enriched Air Nitrox, meaning a mixture containing more oxygen than normal atmospheric air.
Regular air contains approximately:
21% oxygen
79% nitrogen
EAN32 contains:
32% oxygen
68% nitrogen
That difference may not sound dramatic, but it can make an important difference in how much nitrogen your body absorbs during a dive.
What Does Nitrox 32 Mean?
When divers talk about Nitrox 32, EAN32, or simply “32,” they are referring to a breathing gas containing 32% oxygen. The “32” therefore refers to the oxygen percentage.
For example:
Air = approximately 21% oxygen
EAN32 = 32% oxygen
Because EAN32 contains more oxygen, it contains less nitrogen than regular air.
This is the fundamental reason recreational divers use it.
Why Does Nitrogen Matter When Diving?
To understand Nitrox, it helps to understand what happens to your body while scuba diving.
When you descend underwater, the surrounding pressure increases. As you breathe compressed gas from your scuba cylinder, your body absorbs nitrogen from that gas.
The deeper you go and the longer you stay, the more nitrogen your body can absorb.
During your ascent and surface interval, your body gradually releases that nitrogen.
This is one of the reasons scuba divers need to follow their dive computer, decompression limits, ascent procedures, and training.
Because Nitrox contains less nitrogen than regular air, breathing Nitrox can result in less nitrogen exposure for a comparable dive profile. And that is where many of its benefits come from.
Does Nitrox Give You Longer Bottom Times?
This is one of the most common questions about Nitrox.
It can.
Because you absorb nitrogen more slowly when breathing an appropriate Nitrox mix, your theoretical no-decompression limit can be longer at certain depths compared with breathing air.
For example, if two divers make the same dive to the same depth, the diver using an appropriate Nitrox mix may have a longer no-decompression limit than the diver breathing air.
However, there is an important distinction:
Nitrox does not mean you can simply stay underwater for as long as you want. Your actual dive limits depend on your depth, gas mixture, dive profile, computer, repetitive dives, and oxygen exposure.
Nitrox should therefore be viewed as a tool for managing nitrogen exposure, not as permission to ignore normal diving limits.
What Are the Main Benefits of Nitrox?
Nitrox is particularly popular with divers who make multiple dives over several days.
Some of the potential benefits include:
1. Reduced Nitrogen Exposure
The most important benefit is simple: EAN32 contains less nitrogen than regular air.
For an equivalent dive profile, this can reduce the amount of nitrogen your body absorbs.
2. Potentially Longer No-Decompression Limits
At certain depths, Nitrox can provide a longer no-decompression limit than air.
This can be particularly useful on repetitive dives.
3. More Efficient Repetitive Diving
Divers who make two, three, or even more dives per day may appreciate the reduced nitrogen exposure associated with Nitrox.
This is one reason Nitrox is so popular on dive boats and liveaboards.
4. A Useful Option for Dive Vacations
If you are diving every day during a vacation, Nitrox can become particularly useful.
Instead of getting certified after arriving at your destination, you can complete your certification before your trip and arrive ready to dive.
5. Widely Available
Nitrox is now available at dive centers, resorts, liveaboards, and dive boats around the world.
It is particularly common in popular destinations where repetitive diving is part of the experience.
Is Nitrox Safer Than Air?
This is where we need to be careful. You will sometimes hear divers say that Nitrox is “safer” than air. The reality is more nuanced. You will sometimes hear divers say that Nitrox is “safer” than air.
However, Nitrox also contains more oxygen, which introduces oxygen exposure considerations that divers need to understand. As the oxygen percentage increases, the maximum depth at which the gas can be safely used decreases.
This is why Nitrox divers need to understand concepts such as Maximum Operating Depth (MOD) and oxygen exposure. So Nitrox isn't simply “air but safer.”
It is a different breathing gas with advantages and limitations. So Nitrox isn't simply “air but safer.”
Can You Dive Deeper With Nitrox?
No, and this is one of the biggest misconceptions about Nitrox. Having more oxygen in the tank does not mean you can safely dive deeper.
In fact, the opposite can be true. Because Nitrox contains a higher percentage of oxygen, oxygen exposure becomes an increasingly important consideration as depth increases.
Every Nitrox mixture has a Maximum Operating Depth (MOD) based on the oxygen exposure limit used for the dive.
For recreational Nitrox diving, EAN32 is commonly used within appropriate recreational depth limits, but divers must always calculate and respect the MOD for the actual gas they are breathing.
Your Nitrox training teaches you how to determine these limits and use the gas correctly.
Do You Need a Special Certification to Dive Nitrox?
Yes, you should complete an appropriate Enriched Air Nitrox certification before using Nitrox for scuba diving. This training teaches you much more than simply knowing that Nitrox contains 32% oxygen.
You learn how to:
Understand different Nitrox mixtures
Calculate oxygen exposure
Determine Maximum Operating Depth
Read and interpret Nitrox cylinder markings
Analyze the gas in your cylinder
Set your dive computer correctly
Plan Nitrox dives
Understand the benefits and limitations of Nitrox
Apply safe procedures when using enriched air
These are important skills because using the wrong gas settings or exceeding oxygen exposure limits can create serious risks.
Do You Have to Be an SSI Diver to Get Nitrox Certified?
No. One of the advantages of the SSI Enriched Air Nitrox 32 program is that it is available to certified divers from other recognized training agencies as well.
That means you don't need to be an SSI Open Water Diver to take the course. If you are certified through organizations such as PADI, NAUI, SDI, RAID, CMAS, BSAC, or another recognized training agency, you can take the SSI Enriched Air Nitrox 32 course, provided you meet the program prerequisites.
This makes the course particularly convenient for travelers who already hold a certification from another agency.
Can You Get Nitrox Certified Online?
Yes. This is one of the easiest ways to add a useful specialty certification to your diving qualifications. The SSI Enriched Air Nitrox 32 program can be completed online from home.
You don't need to travel to a dive center just to attend a classroom session. You complete the digital learning and final exam online (mobile, tablet or desktop available), allowing you to get certified before your next dive trip.
This is particularly useful if you are planning a:
Dive vacation
Liveaboard
Weekend of repetitive diving
Scuba trip to Costa Rica
Trip to the Caribbean
Diving holiday in Southeast Asia
Multi-day dive safari
Instead of spending part of your vacation completing the theory, you can arrive already certified and ready to use Nitrox where it is available.
Why Is EAN32 So Popular?
There are many different Nitrox mixtures, but EAN32 is one of the most common recreational blends. That makes it a practical certification for traveling divers.
You may encounter Nitrox 32 at dive destinations around the world, including:
Costa Rica
The Caribbean
Mexico
Egypt
Thailand
Indonesia
The Maldives
Liveaboard destinations
The exact Nitrox availability and blend offered will always depend on the dive operator and destination. But getting certified for Nitrox gives you another option when enriched air is available.
Is Nitrox Worth It for Recreational Divers?
For many divers, absolutely. If you only make an occasional single dive, the benefits may be less significant. But if you regularly make multiple dives in a day, Nitrox can be a very useful addition to your diving qualifications.
Think about the typical dive vacation:
You wake up, make a morning dive, surface for breakfast, make another dive before lunch, perhaps do another afternoon dive, and then repeat the process the following day.
That's a lot of repetitive diving.
Nitrox can help reduce nitrogen exposure during those repetitive dives, provided it is used correctly and within the appropriate limits. This is why Nitrox has become such a common certification among recreational divers.
One Important Thing: Nitrox Doesn't Change Your Air Consumption
Another common misconception is that Nitrox makes your tank last longer.
It doesn't.
If you normally consume a certain amount of gas per minute, switching from air to Nitrox doesn't suddenly make you breathe less. Your cylinder still contains a finite amount of breathing gas.
Nitrox can potentially give you a longer no-decompression limit, but your actual dive duration may still be limited by:
Your gas consumption
Cylinder size
Depth
Water conditions
Temperature
Current
Dive plan
Your dive computer
This distinction is important. Nitrox can extend your nitrogen-based dive limits, but it doesn't magically give you more gas.
Should You Get Nitrox Certified Before Your Next Dive Trip?
If you are planning a dive vacation with multiple dives, getting Nitrox certified before you travel can make a lot of sense.
You can complete the theory from home, understand how Nitrox works, and arrive at your destination with the certification already completed. Then, when Nitrox is available, you are ready to use it within your training and the limits of your dive plan.
For a relatively short online course (3 chapters and online exam can be completed in one hour), it can be one of the most useful additions to your diving qualifications.
Get Your SSI Nitrox 32 Certification Online
At Rich Coast Diving in Costa Rica, we offer the SSI Enriched Air Nitrox 32 certification online.
The course can be completed from home, and you do not need to travel to Costa Rica to take it.
You can complete the digital learning and final exam online and receive your SSI certification before your next dive trip.
The course includes:
SSI Digital Learning
Online training materials
Final exam
Digital certification
Whether you're planning your next dive vacation, a liveaboard, or simply want to add one of the world's most popular scuba specialties to your certification portfolio, Nitrox is a useful skill to have.
If you have any questions you can write us directly at info@richcoastdiving.com
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