SSI Enriched Air Nitrox Certification
Your computer beeps. Five minutes left on your no-decompression limit, and you just found the best part of the dive.
On many recreational dives, time runs out before gas does. Enriched Air Nitrox teaches you to use higher-oxygen gas mixtures properly, so you can plan longer no-decompression time at common reef depths while staying within the limits that matter.
Availability: In Stock
Your Computer Beeps. Five Minutes Left. You Just Found the Best Part of the Dive.
Enriched Air Nitrox is the most popular specialty certification in recreational scuba diving. The reason is simple: by breathing a gas blend with more oxygen and less nitrogen than standard air, you absorb less nitrogen per dive. That means longer no-decompression limits, shorter surface intervals, and more time underwater on every dive day.
At Tom’s Dive & Swim we teach the SSI Enriched Air Nitrox 40 certification. SSI offers two nitrox certification levels, but Tom’s teaches EAN40 as standard because it is the more complete credential: it qualifies you to dive with blends up to 40% oxygen and trains you to analyze your own cylinders independently before every dive. We believe every nitrox diver should be able to verify their own gas. The course combines online academics through the MySSI app with a hands-on practical session at 5909 Burnet Rd covering oxygen analyzer use, cylinder labeling, MOD calculation, and fill log documentation. Tom’s fills nitrox on-site, so you can put your certification to work the same day. Prerequisites: SSI Open Water Diver or equivalent from any agency. Minimum age 10.
Course at a Glance
| Price | $225 per diver (group) · $299 per diver (private) |
| Add-on pricing | $149 when bundled with Open Water or another continuing education course |
| Format | Online academics at your own pace via the MySSI app, plus a hands-on practical session at Tom’s |
| Open water dives | None required for certification |
| Duration | Academics: 2 to 3 hours self-paced · Practical session: 2 to 3 hours at Tom’s |
| Location | Tom’s Dive & Swim · 5909 Burnet Rd, Austin TX 78757 |
| Prerequisites | SSI Open Water Diver or equivalent (any agency) · Minimum age 10 |
| Nitrox fills | Available on-site at Tom’s · blends up to 40% oxygen |
| Certification awarded | SSI Enriched Air Nitrox 40 · lifetime certification, recognized worldwide |
| Pathway note | EAN40 is a prerequisite for SSI Decompression Diving and XR Nitrox programs |
Ready to get more bottom time?
SSI Enriched Air Nitrox 40: $225 · Austin, TX
Online academics + hands-on practical session. Bundle with Open Water for $149. Call (512) 451-3425.
Signup now!!How Nitrox Compares to Breathing Air
Nitrox is not a completely different gas. It is a modified blend of the same two gases already in air. Here is what changes and what does not.
| Question | Air | Nitrox |
| Oxygen content | About 21% | Commonly 32% or 36% |
| Nitrogen content | About 79% | Lower than air |
| No-decompression limits | Standard | Extended at recreational depths |
| Surface intervals | Standard | Can be shorter between dives |
| Maximum depth | Recreational limits apply | Shallower than air (oxygen toxicity) |
| Gas consumption | Unchanged | Unchanged |
| Dive computer setup | Standard air mode | Must be configured for the specific blend |
| Certification required | Open Water Diver | Nitrox certification |
| Best used for | All diving | Repetitive dive days, travel, photography |
Understanding the Two Nitrox Certification Levels
SSI offers two Enriched Air Nitrox certifications. Tom’s teaches EAN40 as standard. Here is what the difference means in practice and why we made that decision.
Enriched Air Nitrox 32
Qualifies the diver to use gas blends up to 32% oxygen. Completed entirely through digital academics and a final exam. No in-person practical session required.
The key limitation: with an EAN32 certification, the training center or dive shop analyzes and labels your cylinder before each dive. You are not trained or authorized to do this yourself.
This works fine when you are diving with a shop that handles gas analysis for you. It becomes a constraint at destinations where you need to verify your own fills, or any time you are diving independently.
Enriched Air Nitrox 40
Qualifies the diver to use gas blends up to 40% oxygen. Requires all academics plus a hands-on practical session covering oxygen analyzer calibration, cylinder analysis, MOD calculation, tank labeling, and fill log documentation.
With EAN40, you analyze your own cylinders independently before every dive. You are not dependent on a shop or facility to verify your gas. That independence is the whole point.
Tom’s teaches EAN40 because we think divers should understand and control what they are breathing. The practical session adds a few hours to the course. The skill you gain stays with you for every nitrox dive you ever do.
Who Is the Nitrox Course For?
Nitrox is for certified divers who want to get more out of every dive. Here are the divers who benefit most:
Dive Travelers
Heading to Cozumel, Bonaire, Roatan, or a liveaboard? Nitrox lets you log more dives per day with shorter surface intervals. Most serious dive destinations offer nitrox fills, and many include them free with certification.
Underwater Photographers
Getting the shot takes time. Nitrox gives you more of it. Photographers consistently cite extended bottom time as one of the most practical benefits of nitrox certification, especially at moderate depths where reef life is richest.
Multi-Dive Day Divers
Nitrox reduces the nitrogen load that drives surface intervals. If you plan two or three dives in a day, nitrox gives you back time you would otherwise spend waiting on the surface between dives.
Divers Who Feel Tired After Dives
Many divers report feeling less tired after repetitive nitrox dive days. While the primary proven benefit is extended no-decompression limits from reduced nitrogen exposure, reduced fatigue is a frequently cited secondary effect, particularly after multi-dive days.
DAN Safety Standards
Tom’s follows Divers Alert Network (DAN) safety standards and recommends DAN dive accident insurance for every certified diver. Safety is not a checkbox on our website. It is the foundation of how Tom’s has operated since 1982.
Choose Your Next Step
You dive multiple times per day or spend time at moderate reef depths
Extends your no-decompression time exactly where most recreational diving actually happens.
You want to understand your dive computer’s algorithm itself
Focuses on the technology and decision logic behind every dive computer, a natural pairing with Nitrox.
Your goal is greater depth, not longer bottom time at moderate depth
Nitrox has a shallower maximum operating depth than air. Deep Diving is the right path if depth itself is the goal.
What You’ll Train
Here is how the SSI Enriched Air Nitrox course works at Tom’s Dive & Swim, from enrollment to certification.
After enrolling at Tom’s you receive access to the SSI Enriched Air Nitrox digital training through the MySSI app. Five academic sessions cover nitrox theory, gas laws, oxygen physiology and toxicity, equipment considerations, dive planning, and how to conduct a nitrox dive. Plan on two to three hours of self-paced study.
Each academic session includes knowledge review questions built into the MySSI platform. After completing the academics, you take the final exam. A score of 80% or better is required for certification. All of this is completed digitally at your own pace before coming into Tom’s.
You come into Tom’s for a hands-on practical session with a certified SSI instructor. You will calibrate an oxygen analyzer using a known reference gas, analyze multiple nitrox cylinders of varying blends, calculate the Maximum Operating Depth for each using a ppO2 limit of 1.4 ata, label each cylinder with your name and MOD, and complete the fill log. You must demonstrate each skill correctly and consistently before certification is issued.
What Is Included
Common Misconceptions About Nitrox
"Nitrox lets you dive deeper."
Nitrox has a shallower maximum operating depth than air because of oxygen toxicity limits. The benefit of nitrox is more bottom time at recreational depths, not deeper diving. EAN32 has a MOD of approximately 111 feet at the standard 1.4 ata ppO2 limit. For deeper diving, technical programs are the path.
"Nitrox is only for advanced divers."
Open Water Diver certification is the only prerequisite, and the minimum age is 10. Nitrox is one of the first specialties most instructors recommend after Open Water precisely because the benefits are greatest at the recreational depths new divers are logging.
"Nitrox is dangerous."
Nitrox is widely used in recreational diving and is safe when divers understand and follow oxygen exposure limits. The course covers those limits, how to calculate your MOD, and how to configure your dive computer correctly.
"My dive computer handles it automatically."
Your computer must be manually configured with the correct oxygen fraction before each dive. Diving with a computer still set to air while breathing nitrox means your oxygen exposure is not being tracked accurately. This course teaches exactly how to set it up correctly.
Enriched Air Nitrox Sits in the Optimize Pathway
Optimize is about tools and efficiency. Nitrox is usually the first course divers take in this lane, extending bottom time and reducing surface intervals at the depths most recreational diving actually happens.
Control / Comfort
Buoyancy, navigation, and other confidence-building skills.
Optimize
Nitrox, computers, equipment, and other tools that make diving more efficient.
Access
Wreck diving, deep diving, decompression diving, and other ways to reach new environments and depth.
We build divers we would trust with our own families.
That is not a tagline. It is the standard every Tom’s instructor brings to the water. Since 1982, we have believed that confidence comes from preparation, not luck. That real capability is not something a card represents. It is something you feel the moment buoyancy becomes automatic, navigation feels natural, and you are calm in conditions that would have rattled you six months ago.
We get there by coaching before we criticize, by treating every student as an individual with a specific goal, and by building a team of 30 or more active instructors who are genuinely invested in where you go next. Over 400 five-star Google reviews and more than 18,000 certified divers later, what people tell us they remember is not the card. It is the moment diving clicked.
Open longer than any other Austin dive shop still in business
Tom’s opened in 1982. The other Austin dive shops that are still open today came later. That kind of staying power is not an accident. It comes from building a reputation one diver at a time, over four decades, in the same city, with the same commitment to doing it right. When you train at Tom’s, you are training at the shop Austin’s diving community has trusted the longest.
We coach before we criticize
When something does not click the first time, that is information, not a problem. Our instructors treat every hesitation and every mistake as a signal about what to work on next, not a reason to judge. That approach, calm and honest and focused on what you can do, is what builds the kind of confidence that holds up outside the pool.
Instructors who are divers first
With 30 or more active SSI-certified instructors, we have the depth to match you with the right person for your goals and your schedule. But what matters more than the number is who they are: working divers, active in the water, who teach because the sport means something to them. That shows up in how they engage with every student.
On-site nitrox fills to EAN40
We fill nitrox on-site and teach to EAN40 as the standard, not EAN32. That means your certification qualifies you for higher oxygen fractions and longer bottom times, with the independent cylinder analysis skills to use them. Most shops that offer nitrox training rely on outside fill stations.
Frequently Asked Questions
Nitrox is any breathing gas with more than 21% oxygen. Standard air is approximately 21% oxygen and 79% nitrogen. Recreational nitrox blends most commonly use 32% or 36% oxygen. The higher oxygen content means less nitrogen is absorbed per dive, which extends your no-decompression limits at recreational depths and reduces the nitrogen that drives surface interval requirements.
SSI offers two nitrox certifications. EAN32 qualifies you to use blends up to 32% oxygen and is completed entirely online. With an EAN32 card, the dive shop or training center analyzes your cylinder for you before each dive. EAN40 qualifies you to use blends up to 40% oxygen and includes a hands-on practical session where you learn to independently analyze your own cylinders, calculate MOD, label tanks, and log fills. Tom’s teaches EAN40 as standard because we believe every nitrox diver should understand and verify their own gas. The practical session adds a few hours to the course and the skill is yours for every nitrox dive you ever do. EAN40 is also a prerequisite for SSI Decompression Diving.
The online academics take two to three hours at your own pace through the MySSI app. The practical session at Tom’s takes an additional two to three hours. Many students complete the entire course in a single day.
No. SSI Enriched Air Nitrox certification does not require open water dives. Certification is based on academic knowledge and demonstrated practical skills. You do need a valid Open Water Diver certification from any recognized agency before enrolling.
Yes. Tom’s Dive & Swim fills nitrox on-site at 5909 Burnet Rd. We offer blends up to 40% oxygen. You need to present a valid nitrox certification card each time you pick up a nitrox fill.
Maximum depth on nitrox is set by oxygen partial pressure limits, not nitrogen. The standard recreational limit is a ppO2 of 1.4 ata during the dive. The maximum operating depth varies by the blend you are using: EAN32 gives an MOD of approximately 111 feet at 1.4 ata; EAN36 approximately 95 feet. The course covers how to calculate MOD for any blend using Dalton’s Diamond, and how to configure your dive computer to alert you when you approach the limit.
For recreational blends up to 40% oxygen, most standard dive equipment is compatible without modification. Your dive computer needs to support nitrox mode, which most modern computers do. Tom’s provides the oxygen analyzer and all required equipment for the practical session. Your instructor will review compatibility of your personal gear during that session.
Yes. Central Texas dive sites are well within recreational nitrox depth limits. At shallower depths, the no-decompression limit extension that nitrox provides is especially pronounced. You would need to bring nitrox fills from Tom’s or confirm availability at the site. Tom’s can fill your tanks before your lake day.
Yes. SSI certifications are recognized by dive shops, resorts, and liveaboards worldwide. The nitrox standard is consistent across training agencies, and your SSI card will be accepted anywhere that offers nitrox fills. Like all SSI certifications, it is a lifetime credential and never expires.
Yes. SSI allows students to complete the Enriched Air Nitrox academic and practical application sessions during Open Water Diver training and earn both certifications simultaneously. Tom’s offers this as a bundle starting at $149 for the nitrox add-on. Ask about combining courses when you enroll.
Ready to get more bottom time?
SSI Enriched Air Nitrox 40: $225 · Austin, TX
Online academics + hands-on practical session. Bundle with Open Water for $149. Call (512) 451-3425.
Signup now!!What Comes Next?
Nitrox certification opens up your diving in more ways than just bottom time. Here is where most nitrox-certified divers go next.