Here are some terms used in scuba diving:
_Air: a gas mixture containing 21% oxygen, 78% nitrogen, and 1% other gases (mainly argon); compressed air is used for recreational scuba diving.
_Buoyancy compensator: An inflatable vest worn by the diver that can be automatically or orally inflated to help control the diver’s ability to float or sink; usually referred to as a BC.
_C-Card: A diver’s certification card for a specific level of achievement.
_Dry suit: A water-tight garment that keeps the diver’s body warm by providing insulation with a layer of gas, such as air; for diving in waters that are too cold for comfortable wetsuit protection, usually below 65F.
_Equalization: The act of forcing air into an open space to offset increasing water pressure.
_Mask squeeze: Occurs in rapid descents where the diver neglects to equalize his/her mask. The increasing pressure causes tissues around the eyes to swell.
_Nitrox: Any mixture of nitrogen and oxygen that contains less than the 79% nitrogen found in ordinary air.
_Recreational scuba diving: Diving to prescribed limits, including a depth no greater than 130 feet, using only compressed air, and never requiring a decompression stop.
_Residual nitrogen time: The time it would take to vent any extra nitrogen remaining after a dive. Residual nitrogen time is always taken into consideration when determining the safe duration for any repetitive dive.
_SCUBA: An acronym meaning Self-Contained Underwater Breathing Apparatus.
_Thermocline: Intersection between two layers of water that are distinctly different temperatures, usually the colder layer is deeper.
_Wet suit: Any suit that provides thermal protection underwater by trapping a layer of water between the diver’s skin and the suit.