In diving when we talk about pressure you will hear different terms or you are familiar with one or two of them. Depending on where you grew up you either use BAR or PSI „pound per square inch,” Psi is more commonly used in North America and bar you’ll find in the rest of the world. Another term you are familiar with is atmospheres. You might have also heard of msw „meters of salt water“ or mfw „meters of fresh water“. This is common used for the maximum pressure rating of an underwater housing.
But as a PADI Professional the most important ones are Absolute „ATA“ and Gauge pressure: