Pressure and Volume Pressure is created by the force of gravity pulling down on matter that is above an object. We experience this pressure every day in the form of air pressure but don't think about it as we are used to the force being constantly applied to our bodies. We still notice its effects however when our ears pop due to a change in altitude (our internal pressure equalizing with the surrounding environment) or when we go up into the mountains the air becomes thinner (the atmospheric pressure is decreased so the density of the air is also decreased). These concepts of pressure are very important in diving. Because the mass of water is much higher than that of air the change in pressure created by descending in water is much higher than that of moving through air. For every 10 m (about 33ft) you descend through water it creates the same force as the entire atmosphere does at sea level. While this force does not compress the water a noticeable amount, it does affect the volume and density of air which is exposed to this force.