Nitrox Diving ExplainedShould You Get PADI Enriched Air Certified?

Specialty Certification Tioman Dive Buddy Updated May 2026 7 min read Quick Answer

Nitrox (also called Enriched Air or EAN) is a breathing gas containing more oxygen than regular air — typically 32% or 36% oxygen, compared to air's 21%. The benefit: less nitrogen means longer no-decompression bottom times and shorter surface intervals. The cost: limited maximum depth due to oxygen toxicity risk. PADI Enriched Air Diver certification (1 day, ~RM 1,000) teaches you to dive nitrox safely. It's the most popular specialty PADI offers for good reason.

Key Takeaways

• Nitrox = breathing gas with 22-50% oxygen (air is 21%)
• Most common: EAN32 (32% O₂) and EAN36 (36% O₂)
• Main benefit: potentially longer no-decompression limits, depending on the dive profile
• Main limit: maximum depth ~30-40m depending on mix
• Course: 1 day, ~RM 1,000 at Tioman Dive Buddy
• Required for: Tec 40 (Nitrox prerequisite), most extended-range diving

What Is Nitrox?

Regular air at sea level is approximately 78% nitrogen, 21% oxygen, and trace gases. When you dive on air, nitrogen accumulates in your tissues — too much causes decompression sickness.

Nitrox replaces some of the nitrogen with oxygen. Common Nitrox mixes:

• EAN21: 21% oxygen (same as air)
• EAN28: 28% oxygen
• EAN32: 32% oxygen (most common recreational mix)
• EAN36: 36% oxygen (popular for shallower dives)
• EAN40: 40% oxygen (used in Tec)
• EAN50: 50% oxygen (deco gas, Tec only)
• 100% O₂: Pure oxygen (deco gas, Tec only)

For recreational diving, EAN32 and EAN36 are the workhorses.

The Benefits of Nitrox

1. Longer Bottom Times

At the same depth and dive profile, a suitable enriched-air mix has less nitrogen than air. This can extend the no-decompression limit when the mix and dive computer are set correctly. The actual limit depends on the gas, previous dives, depth profile and computer settings; there is no fixed extra time for every dive.

2. Shorter Surface Intervals

Using an appropriate nitrox mix may allow a shorter surface interval for a planned repetitive dive, but this is calculated from the whole dive series and the specific computer or table. Always follow your actual plan and the longest required interval among the divers in your group.

3. Reduced Fatigue (debated)

Some divers report feeling less tired after nitrox dives, but research has not established that nitrox reduces post-dive fatigue. Do not use a perceived energy boost as a reason to extend your dive plan.

The Limitations

Limit 1: Maximum Operating Depth

The higher the oxygen percentage, the shallower the maximum depth. Oxygen becomes toxic at depth.

Maximum Operating Depth (MOD):

• EAN32: 33m / 110ft
• EAN36: 28m / 92ft
• EAN40: 24m / 80ft

Standard recreational limits are 40m / 130ft on air. With nitrox, you're depth-limited but bottom-time-extended.

Limit 2: Oxygen Toxicity Risk

If you exceed MOD, breathing nitrox can cause:

CNS oxygen toxicity can cause a seizure underwater, creating a serious drowning risk.

Pulmonary Oxygen Toxicity — Lung tissue damage over long exposure. Rarely an issue in recreational diving.

The PADI Nitrox course teaches you to plan your dives so MOD is never exceeded.

Limit 3: Gas Cost

Nitrox costs more than air. A single nitrox tank typically:

• EAN32: RM 30-50 per tank (vs RM 25-35 for air)
• EAN36: RM 35-55 per tank
• EAN40: RM 45-65 per tank

Over a dive trip, this adds up. But for multi-dive days, the additional bottom time often justifies the cost.

How the PADI Enriched Air Course Works

The PADI Enriched Air Diver (Nitrox) specialty is one of the simplest and most popular specialties. It teaches:

Knowledge development:

• What is nitrox? How does it work?
• Calculating Maximum Operating Depth (MOD)
• Calculating Equivalent Air Depth (EAD)
• Tank analysis (verifying oxygen percentage)

Practical:

• Tank analyzer use
• Computer setup for nitrox mode
• Up to two optional open-water dives on nitrox

Duration: 1 day (~6 hours total) Cost at TDB: RM 1,000 Prerequisites: Open Water certification

When to Get Nitrox Certified

Get nitrox now if you:

✅ Plan to dive multiple times per day on dive trips ✅ Are interested in any deeper diving (AOW, Wreck) ✅ Want to pursue Tec 40 (Nitrox is a prerequisite) ✅ Travel to dive — every minute of bottom time matters

Skip nitrox if you:

❌ Only dive once or twice a year casually ❌ Are budget-constrained and want only essentials ❌ Plan to stay in shallow water (5-15m) where nitrox advantages are minimal

Nitrox Safety Protocols

Every nitrox dive starts with these steps:

1. Verify your tank percentage using an oxygen analyzer
2. Set your dive computer to match the percentage
3. Confirm Maximum Operating Depth for your mix
4. Brief your buddy on the dive plan
5. During dive: never exceed MOD
6. Surface and log: complete safety stop, log dive details

These checks are essential to keeping the gas and dive plan within safe limits.

The Cost-Benefit Calculation

Compare the course and fill price with the diving you actually plan to do. Nitrox may be useful for repetitive or longer dives within its maximum operating depth, but it does not guarantee extra dives, a set percentage of extra bottom time, reduced fatigue or a financial saving. Ask your instructor to review your dive plan and the available gas mixes.

Nitrox Misconceptions

"Nitrox makes you dive deeper" — FALSE. It's actually MORE depth-restrictive than air.

"Nitrox is always safer than air" — FALSE. It can reduce nitrogen exposure on some profiles, but it increases oxygen exposure and has a shallower maximum operating depth. Training and correct planning matter.

"You need nitrox for AOW" — FALSE. AOW is air-only at the recreational level.

"Nitrox is a tec gas only" — FALSE. Recreational EAN32 is widely used.

Frequently Asked Questions

About the Author

Tioman Dive Buddy — PADI 5★ IDC in Kampung Genting. We dive Tioman's reefs daily during season and have trained thousands of divers since 2010.