| Acronym | Meaning |
| NAUI | National Association Of Underwater Instructors |
| IDC | Instructor Development Course (PADI) |
| DIR | Doing It Right |
| NITROX | Any Gas Mixture Of Nitrogen And Oxygen; Though Most Commonly Used For Oxygen Mixtures Above The Normal 21 Per Cent. |
| MSDT | Master SCUBA Diver Trainer (PADI) |
| OWI | Open Water Instructor (BSAC) |
| ATA | Atmospheres Absolute |
| ABT | Actual Bottom Time |
| PP | Partial Pressure |
| SAA | Sub-Aqua Association |