Enriched Air Nitrox course: what you learn, how long it takes and which agency to choose

Enriched air nitrox is a breathing gas with more oxygen and less nitrogen than normal air (which is about 21% oxygen). Less nitrogen means longer no-decompression times on repetitive dives, or a bigger safety margin if you keep to air limits. The trade-off is a shallower maximum depth, because oxygen becomes toxic under pressure. Our article on nitrox benefits and myths explains what the research says, including whether nitrox makes you less tired.

You need a nitrox certification before you can dive on it. On our day trips, nitrox is blended on board for certified nitrox divers.

• Analysing your gas: checking the oxygen percentage in your own cylinder with an analyser before every dive, and marking the cylinder
• Maximum operating depth (MOD): working out the deepest you can go on a mix. At the usual limit of 1.4 bar oxygen partial pressure, EAN32 has an MOD of about 33 m, EAN36 about 28 m and EAN40 about 25 m
• Oxygen exposure: tracking how much oxygen you have breathed over a day of diving
• Your dive computer: setting the right mix, so its no-decompression times match what you are breathing
• Planning: choosing a mix for the depth of the dive

Certified Open Water divers. SSI's Enriched Air Nitrox course has a minimum age of 10, can be combined with Open Water training and suggests 3–6 hours; Open Water certification is required before the nitrox card is issued. You earn a 32% or 40% certification. Dives are optional: any dive stays within your certification, junior limits and the analysed mix's maximum operating depth, even if the course page lists 30 m. It is mostly theory and hands-on gas analysis, so we fit it around a dive day, and you can make your first nitrox dives on the same trip.

All four teach the same core skills. Choose the agency you already dive with, or the one you plan to continue with:

• PADI Enriched Air Nitrox Diver: analysing enriched air and planning within oxygen exposure limits
• SSI Enriched Air Nitrox (32%/40%): gas analysis, oxygen limits and MOD, computer settings
• SDI Enriched Air Nitrox: analysing nitrox, oxygen exposure and MOD
• TDI Nitrox Diver: mixes from EAN22 to EAN40, gas analysis, cylinder marking and oxygen exposure. TDI is the technical agency, so it suits divers heading towards technical diving

Today's prices are on each course page and on our price list.

No, the opposite. More oxygen means a shallower maximum operating depth than air. Nitrox lets you stay longer at recreational depths, not go deeper. For the depth limits of recreational diving itself, see how deep can recreational divers go.