What is the definition of "absolute pressure" in the context of diving?

Absolute pressure in the context of diving is defined as the total pressure at a given depth, which includes both the atmospheric pressure and the pressure due to the water column above the diver. At sea level, atmospheric pressure is about 14.7 psi (or approximately 1 atm), and as a diver descends, the water pressure increases alongside the existing atmospheric pressure. Therefore, to calculate the absolute pressure experienced by a diver at a specific depth, you would add the weight of the water above to the atmospheric pressure, resulting in a higher total pressure than what is felt at the surface. This understanding is crucial for divers to ensure safe diving practices and to properly manage effects related to pressure, such as nitrogen absorption and potential risks of decompression sickness.