What is the atmospheric pressure at sea level?

At sea level, the atmospheric pressure is defined as 1.0 bar, which is equivalent to 1013.25 hPa (hectopascals) or 14.7 psi (pounds per square inch). This pressure is created by the weight of the air above the Earth's surface and is a standard reference point for many scientific calculations, including those relevant to scuba diving.

Understanding the significance of atmospheric pressure is crucial for divers, as changes in pressure directly affect buoyancy and gas behavior during dives. For example, as a diver descends underwater, the pressure increases, which can influence the way gases are absorbed in the body and how they must be managed during ascent to avoid issues like decompression sickness. Therefore, recognizing that the atmospheric pressure at sea level is 1.0 bar is fundamental to grasping these principles effectively.