What is scuba diving on enriched air and how to get nitrox certified

Helping women scuba dive confidently, I answer the many questions about diving on Nitrox. Diving Nitrox isn’t just for technical divers; many recreational divers choose to dive Nitrox. What are the pros and cons of Nitrox diving? Should scuba women use Nitrox when scuba diving? What is diving Nitrox? Do you need to be certified to dive on Nitrox? What is the difference between Nitrox, Enriched Air, EANx, and EAN?


  1. Are Nitrox, Enriched Air, EAN, and EANx the same?
  2. What are the benefits of diving with Enriched Air (Nitrox)?
  3. What happens when you breathe underwater with a scuba tank?
  4. How can you tell a nitrox tank from a regular scuba tank?
  5. What you need to know to dive safely with Enriched Air (Nitrox)?
  6. Interested in how to get PADI Enriched Air (Nitrox) certified?

Are Nitrox, Enriched Air, EAN, and EANx the same?

In our everyday life on land, we breathe regular air, roughly 21% oxygen, and 78% nitrogen. When we venture underwater, we breathe the same mix of air from our scuba tanks. When we switch from Air Diving to Enriched Air Diving, the oxygen and nitrogen ratios in the gas mixture change.

"Nitrox Here" sign on gutter of dive hut

Nitrox, Enriched Air, EAN, and EANx all refer to the amount of nitrogen and oxygen in our scuba tanks when the oxygen level is higher than 21%.

A PADI Nitrox course teaches divers how to analyze a nitrox tank and enter the oxygen percentages into their dive computers.

What are the benefits of diving with Enriched Air (Nitrox)?

A big benefit of diving on Enriched Air (Nitrox) is extended bottom times as our No Decompression Limits (NDL) increase. Nitrox for extended bottom times is generally most useful when diving between 15m (50ft) and 30m (98ft).

The ratios of the mix will affect bottom times and maximum depths. As the oxygen percentage increases so do bottom times, while maximum depths decrease. For example, Nitrox 32 allows scuba divers to have longer bottom times and to dive to a maximum depth of 33 meters (110ft). Nitrox 36 also extends bottom times though the maximum operating depth decreases to only 28 meters (90ft).

A collection of nitrox scuba tanks

The most common blends for recreational divers are Nitrox 32 (EAN32), a mix of 32% oxygen and 68% nitrogen, or Nitrox 36, a blend of 36% oxygen and 64% nitrogen. Oxygen levels can be as high as 40%, though it is unusual for recreational divers to use such a high mix. The oxygen percentage is rarely precisely 32%; it will usually fall between 32% and 36%.

Another benefit to diving on Nitrox is shorter surface intervals, as there is less nitrogen to off-gas.

Being an Enriched Air Diver (Nitrox, EAN, EANx) with reduced nitrogen levels means our bodies absorb less nitrogen, lessening the risk of DCS and even Nitrogen Narcosis.

A scuba woman with a nitrox scuba tank

Nitrox divers also have longer bottom times on repetitive dives. Nitrox divers claim to be less fatigued at the end of a day’s diving, and this may be due to less nitrogen in their bodies or less time needed to off-gas at surface intervals. Diving on EAN is perfect for liveaboards when divers typically dive several times a day. To date, the evidence collected is anecdotal; there are no scientific studies to prove divers are less fatigued when diving on Nitrox.

I always choose to dive on Nitrox when I know I will be diving a lot. I have completed liveaboards when diving on EAN and feel great at the end of a trip, in no way fatigued.

What happens when you breathe underwater with a scuba tank?

When scuba diving, the pressure of the water at depth causes the nitrogen we breathe to be absorbed by our bodies. Over the course of a dive nitrogen builds up in our body tissues.

A scuba woman with an enriched air tank

We need to allow time for the absorbed nitrogen to leave our bodies to avoid Decompression Sickness (DCS). Decompression sickness occurs when the dissolved nitrogen gas enters our body tissues as bubbles.

Decompression sickness can cause pain and fatigue, and, at worse, death. Scuba Divers minimize the risk of DCS by ascending slowly, watching bottom times, performing safety stops, and having adequate surface intervals. These precautions allow our bodies to expel the absorbed nitrogen safely. Higher oxygen levels and lower nitrogen levels in our body when diving on Enriched Air lessen the likelihood of Decompression Sickness.

How can you tell a nitrox tank from a regular scuba tank?

Nitrox tanks have distinctive yellow and green banding. Nitrox tanks are filled separately from regular tanks, as the higher oxygen percentages can cause tanks to explode. Before diving on a tank filled with Nitrox, the air must always be analyzed so the diver knows what percentages of oxygen and nitrogen are in the tank.

3 Enriched air tanks on a jetty by a lake

Scuba divers record the percentage on a tag on the tank and a log. The oxygen percentage must be adjusted on your dive computer to match the tank. The PADI Enriched Air Diver Nitrox certification teaches scuba divers how to correctly analyze a Nitrox tank, record the results, and adjust their computer to the correct Nitrox setting. Analyzing a Nitrox tank is crucial as the mix will affect maximum operating depths. If maximum depths are exceeded, a diver risks their life.

What you need to know to dive safely with Enriched Air (Nitrox)?

Diving on Enriched Air allows for longer bottom times but does not allow you to dive deeper. Oxygen can become toxic under pressure. Diving on Enriched Air with higher oxygen percentages increases the risk of oxygen toxicity at depth.

As scuba divers increase their tanks’ oxygen levels, they are more susceptible to oxygen toxicity. Oxygen toxicity can occur without warning causing a diver to convulse and possibly drown.

Analyzing a Nitrox tank

To keep safe, follow your training, and do not exceed your maximum operating depth. For example, if you were diving on EAN36, your maximum operational depth would be 28 meters (90ft). Diving deeper than 28 meters (90ft) would put you at risk of oxygen toxicity. EAN36 would be a better mix for a shallower dive of 20 meters (66ft), where you will not exceed your maximum operating depth but will benefit from less nitrogen in your body and longer bottom times.

Oxygen toxicity occurs when the oxygen reaches a critical level and is known as partial pressure. Partial pressure is the pressure of a mix of gas. The recommended partial pressure for oxygen is 1.4, though 1.6 can also be used. The partial pressure is recorded on your dive computer. Every Nitrox tank must be analyzed and documented before you dive, and your dive computer must be updated.

Interested in how to get PADI Enriched Air (Nitrox) certified?

The PADI Enriched Air (Nitrox) certification teaches divers to analyze the gas mix in their tanks, adjust their dive computers, and understand the physiology of the gas mixes on our bodies, partial pressures, and the maximum operating depth to avoid oxygen toxicity.

I completed my PADI Nitrox Certification training before my first liveaboard and value the certification immensely.

Liveaboard boat for scuba diving on calm water

I completed my theory online through PADI e-learning before meeting my instructor on the liveaboard. After completing a short exam, I was shown how to analyze a tank, fill out an enriched air log, set my dive computer for Nitrox, and understand my maximum operating depth. You may also do two additional dives though they are not compulsory. As I was on a liveaboard, it was not a problem.

As a PADI-trained Enriched Air (Nitrox) Diver, you will be expected to analyze your own tanks with an analyzer before each dive and enter the percentages into your dive computer to know your maximum operating depth.

The minimum age to take the PADI Enriched Air (Nitrox) Diver course is 12 years. The minimum pre-requisite is a PADI Open Water Diver qualification or the equivalent.

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Published by emptynestdiver

Learning to dive in my fifties has been a great adventure, I am a senior scuba diver but young at heart.

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