As depth increases, pressure increases. For example, if a person is diving underwater, the pressure on the diver's body greatly increases the deeper she swims.
Liquids exert the same pressure in all directions at a given depth. Pressure and depth have a directly proportional relationship because of the greater column of water pushed down onto a submersed object. When objects are submersed deeper, the pressure increases. When objects are lifted and the depth is decreased, the pressure decreases.
The relationship between pressure and depth greatly affects scuba divers. When divers are at sea level, no pressure is felt because the air pressing down on the body is equal to the usual pressure of the body's fluids. Divers must be very careful of how fast they descend and ascend, as it takes time for internal and external pressure to equalize. If a diver ascends too quickly, the retained air at higher pressure may cause the diver's ears or lungs to burst. Similarly, absorbed nitrogen gas can bubble out on ascension, leading to a potentially fatal condition called "the bends." On the other hand, if a diver descends into deeper waters too quickly, it creates a situation similar to an internal vacuum, causing membranes to rupture.