| Acronym | Meaning |
| NITROX | Any Gas Mixture Of Nitrogen And Oxygen; Though Most Commonly Used For Oxygen Mixtures Above The Normal 21 Per Cent. |
| ABT | Actual Bottom Time |
| OWI | Open Water Instructor (BSAC) |
| CESA | Controlled Emergency Swimming Ascent |
| ADT | Actual Dive Time |
| ITS | Instructor Training Scheme (BSAC) |
| ITC | Instructor Training Course (BSAC) |
| PDIC | Professional Diving Instructors Corporation International; Diving Instruction Organization. |
| SWP | Safe Working Pressure |
| SSI | Scuba Schools International; Diving Instruction Organization. |