Two methods of measuring air pressure are BAR and:

The answer is PSI, which stands for pounds per square inch. This unit is commonly used to express pressure in various fields, including scuba diving, where it is important for measuring the pressure of gases in tanks and monitoring the pressure during dives.

When you're diving, understanding PSI is crucial as it directly relates to how much air is available to you in your tank. For example, a standard scuba tank might be filled to 3000 PSI. Monitoring this effectively ensures divers can plan their dives and manage their gas consumption appropriately.

While other units like ATM (atmospheres), MMHg (millimeters of mercury), and PA (Pascals) are also valid measures of pressure, PSI is particularly relevant and widely used in scuba diving contexts. It allows divers to communicate and understand pressures in a way that is practical and standardized within the diving community.