Hydrostatic pressure is the pressure exerted by a fluid at rest due to the force of gravity. It increases with depth, meaning that the deeper you go in a fluid, the greater the pressure. This is why divers experience more pressure as they descend underwater. The formula for calculating hydrostatic pressure is P = ρgh, where P is the pressure, ρ is the fluid density, g is the acceleration due to gravity, and h is the height of the fluid column above the point in question. This principle is important in various fields, including engineering and meteorology.