高氧（Nitrox，亦称Enriched Air），是指以空气为基础、氧浓度高于21%的潜水用呼吸气体。借由把气瓶中的氧浓度增加、氮浓度减少，潜水员会减少吸入体内的氮气，从而在同样的潜水深度时可以延长其免减压极限。

在休闲潜水中最参见的混合氧浓度是32%及36%，其最大可用深度（maximum operating depths, MOD）相应为34米和29米。

Nitrox refers to any gas mixture composed (excepting trace gases) of nitrogen and oxygen. This includes atmospheric air, which is approximately 78% nitrogen, 21% oxygen, and 1% other gases, primarily argon. In the usual application, underwater diving, nitrox is normally distinguished from air and handled differently. The most common use of nitrox mixtures containing oxygen in higher proportions than atmospheric air is in scuba diving, where the reduced partial pressure of nitrogen is advantageous in reducing nitrogen uptake in the body's tissues, thereby extending the practicable underwater dive time by reducing the decompression requirement, or reducing the risk of decompression sickness (also known as the bends).