Scuba Diving Glossary

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C-CARD: Refers to a diver's certification card for a specific level of achievement.

CAPILLARY DEPTH GAUGE: Made up of a small tube. Uses Boyle's law to determine depth.

CARBON DIOXIDE: CO2; an odorless, tasteless gas that is a byproduct of metabolism; is excreted by the lungs in exhaled air.

CARBON DIOXIDE TOXICITY: Problems resulting from buildup of CO2 in the blood; they may range from headache and shortness of breath, all the way to sudden blackout.

CARBON MONOXIDE: CO; odorless, tasteless, highly poisonous gas given off by incomplete combustion of hydrocarbon fuels.

CARBON MONOXIDE POISONING: Carbon monoxide bonds with hemoglobin and prevents blood cells from carrying oxygen. This causes oxygen deprivation in the tissues and can even cause death.

CARBON MONOXIDE TOXICITY: Illness from inhaling excess carbon monoxide; problems may range from headache to unconsciousness and death.

CAVERN: Term used to describe a naturally occurring overhead diving environment where daylight is still available. This daylight is considered the "primary light source" for cavern diving. Different cave training agencies have slightly different definitions of what constitutes the "cavern zone" with depths that range from 70 to 130 fsw and pentration distances that range from 50 to 200 feet.

CENOTE: A cenote (from Yucatec Maya dzonot or ts'onot, meaning 'well') is a sinkhole with exposed rocky edges containing groundwater. It is typically found in the Yucatan Peninsula and some nearby Caribbean islands. The term derives from a word used by the low-land Yucatec Maya to mean any location with accessible groundwater. Commonly dove by cavern and cave divers. Generally found in Tulum, Akumal, and Playa del Carmen.

CHARLES' LAW: The amount of change in volume of a gas at constant pressure is directly proportional to the change in the absolute temperature. Similarly, if the volume remains fixed, then the amount of change in pressure is directly proportional to the change in the absolute temperature.

CLOSED CIRCUIT SCUBA: Apparatus designed to allow divers to rebreathe exhaled air after removal of CO2 and addition of supplemental O2. In contrast to "open circuit", closed circuit Scuba is noiseless and produces no bubbles.

COMPARTMENT: A theoretical division of the body with an arbitrarily assigned half time for nitrogen uptake and elimination. In designing decompression tables the body is divided into a finite number of compartments for purposes of making calculations.

COMPUTER: A device that monitors nitrogen in the body during a dive through mathematical algorithms. The device allows divers to multilevel dive and extend bottom time beyond what a dive table allows.

CORAL: Invertebrates that secrete an internal, hard skeletal structure composed of calcium carbonate, which is absorbed from the surrounding water.

CORE TEMPERATURE : The internal temperature of the body. 98.6 F is the normal temperature of the human body. Deviation from this temperature even a few degrees could be life threatening.