Used in Scuba diving. It is a a breathing gas consisting of air mixed with a higher percentage of oxygen than normal air (above 40% is uncommon within recreational diving). The two most popular blends are EANx32 and EANx36 (also named Nitox I and Nitrox II).
There are several ways of mixing Nitrox. One can fill some pure oxygen onto a tank and then fill with air to make the wanted mix. Another way is to remove nitrogen from air with a special filter/membrane or have it premixed industrially.
Using EANx means that the rate of nitrogen absorption into the body is reduced. So the length of time a diver can remain at depth without requiring decompression increases (115 minutes versus 55 minutes at 60 feet) and the risk of [decompression sickness]? is reduced by lowering the nitrogen levels within the diver's body tissues.
Diving with Nitrox and dealing with Nitrox mixes raises a number of potentially fatal dangers due to the high partial prssure of oxygen. Tanks may explode if treated improperly.
It is not a deep-diving gas mixture.