How much pressure is exerted by one atmosphere at sea level?

One atmosphere at sea level exerts a pressure of 14.7 psi (pounds per square inch). This value is a standard reference in various scientific and engineering contexts, particularly in fields related to fluid dynamics, meteorology, and diving. The concept of atmospheric pressure being defined at sea level is crucial for divers, as it affects buoyancy, gas volumes, and overall safety in underwater operations.

When considering diving, understanding the pressure exerted by one atmosphere helps divers calculate how the pressure increases with depth—specifically, that pressure increases by approximately 0.43 psi for every foot of seawater. Therefore, at a depth of 33 feet, a diver experiences two atmospheres of pressure, equivalent to about 29.4 psi. This base understanding of atmospheric pressure is essential for proper dive planning and ensuring safety measures are in place to minimize risks associated with decompression sickness, gas narcosis, and other pressure-related hazards.