How is one atmosphere of pressure defined in relation to depth?

One atmosphere of pressure is defined as the pressure exerted by the weight of the atmosphere at sea level, which is equivalent to approximately 14.7 pounds per square inch (psi) or 1013.25 millibars. When diving, the understanding of pressure is crucial, particularly how it increases with depth underwater.

As a diver descends, the pressure increases due to the weight of the water above them. For every 33 feet of depth in saltwater, the water pressure increases by one atmosphere. In freshwater, the pressure increases by one atmosphere for every 34 feet due to the difference in density between saltwater and freshwater. The term "ata" refers to "atmospheres absolute," and one ata represents the pressure at sea level plus the pressure at a depth of 33 feet in saltwater or 34 feet in freshwater.

Therefore, all the statements regarding how one atmosphere of pressure is defined and its relation to depth are accurate, making the selection of all answers being correct appropriate. Understanding these distinctions is important for divers in managing pressure effects during dives, such as equalizing and addressing the risks of decompression sickness.