Nitrox is the term used to describe a specially enriched blend of oxygen and nitrogen used by professional and experienced scuba divers. The usual accepted mix for Nitrox contains more than the regular 21% percentage of oxygen as is found in regular air, this can be anywhere from 22% of the mix up to the maximum of 40%. The most popular amounts for Nitrox mixes are 32% and 36%.
Also known as enriched air, this increased oxygen mix allows divers to extend the amount of time they spend at depth underwater (bottom time). Nitrox has been used by military dive teams the world over with much success, and they have produced many guidelines on its safe use by professional and recreational divers alike.