Water pressure increases with depth because of the increased weight and volume of the fluid above. The pressure a diver experiences at a given depth is the sum of all the pressures above that diver, from both the water and the atmosphere.
At sea level, the atmosphere is pressing down on our bodies at 14.5 pounds per square inch (1 bar). This is equal to the pressure of our bodily fluids pushing outward. As a person dives in water, the pressure increases 1 bar for every 33 feet of depth. According to the National Oceanic and Atmospheric Administration, the pressure in the deepest part of the ocean is equivalent to a person trying to support 50 jumbo jets.