The Benefits of Scuba Diving With Nitrox

Nitrox tanks on diving boat, Island Malapascua, Cebu, Philipines
Franco Banfi/WaterFrame/Getty Images

 

There are many benefits to using nitrox while scuba diving, as well as risks and considerations for nitrox use. Nitrox is a term that describes a gas that's a combination of nitrogen and oxygen—specifically, with an oxygen content higher than 21%—and may be referred to as Enriched Air Nitrox. 

Recognizable by its green-and-yellow diver's tank labels, nitrox for recreational diving is typically between 28% and 40% oxygen with the most popular formulation at 32% oxygen.

1. Longer Bottom Times

Recreational nitrox contains a lower percentage of nitrogen than the atmospheric air, or the air you breath on a daily basis, as well as regular divers' tanks with air. The reduced percentage of nitrogen in recreational nitrox allows divers to extend their no-decompression limits by reducing nitrogen absorption. For example, according to the National Oceanographic and Atmospheric Association (NOAA) no-decompression dive tables, a diver using Nitrox 36 (or NOAA Nitrox II) may stay up to 50 minutes at 90 feet of seawater, while a diver using air may only stay a maximum of 30 minutes at this depth.

2. Shorter Surface Intervals

A diver using nitrox absorbs less nitrogen on a given dive than one who uses air. This means that the nitrox diver has less nitrogen to off-gas during the surface interval, which can shorten the required surface interval drastically. For example, a diver using Nitrox 32 can repeat a 50-minute dive to 60 feet after 41 minutes, while a diver using air must wait a minimum of eight hours to repeat the same dive (using NOAA's no-decompression dive tables).

3. Longer Repetitive Dive Times

Nitrox becomes especially useful for divers who engage in more than one dive per a day. A diver using nitrox will have a longer allowable bottom time on a repetitive dives than a diver using air because the diver using nitrox has absorbed less nitrogen. For example, after a dive to 70 feet for 30 minutes, a diver using Nitrox 32 can stay at 70 feet for a maximum of 24 minutes if he immediately reenters the water. However, a diver performing the same series of dives on air may only stay at 70 feet for 19 minutes on his second dive, according to NOAA's no decompression dive tables.

4. Exhaustion

Many divers claim to feel less exhausted after a dive on nitrox than after a comparable dive on air. By reducing a diver's nitrogen absorption, nitrox may also reduce a diver's post-dive exhaustion. This is not  proven, but enough divers claim to feel this effect that it is definitely a consideration. Three peer-reviewed studies reported divers' claims of less exhaustion but did not provide reliable data to solve the mystery.

5. Shorter Decompression

Technical divers use nitrox to reduce decompression requirements. If nitrox is used throughout the dive, the diver may require shorter or fewer decompression stops. If nitrox is used as a decompression gas (the diver only breathes nitrox during the decompression stops), the decompression stops will be shorter.