| Acronym | Meaning |
| CNS | Central Nervous System |
| PSI | Pounds Per Square Inch |
| DM | Dive Master (PADI) |
| SAA | Sub-Aqua Association |
| AI | Assistant Instructor (PADI) Advanced Instructor (BSAC) |
| HPNS | High Pressure Nervous Syndrome |
| AIE | Advanced Instructor Exam (BSAC) |
| NI | National Instructor (BSAC) |
| MSD | Master SCUBA Diver (PADI) |
| BHA | British Hyperbaric Association |