Diving Glossary
Complete dictionary of scuba diving terms — English / French
ReferenceEN/FR
ℹ️ Definitions for informational and educational purposes. See our gas laws guide and FFESSM levels for more details.
A-B
- Barotrauma (FR: Barotraumatisme) — Injury caused by pressure changes on air-filled spaces (ears, sinuses, lungs, teeth). Prevention: regular equalization, never hold breath.
- Buddy system (FR: Palanquée) — Diving in pairs for mutual safety. FFESSM uses "palanquée" (2-3 divers) led by the most qualified diver.
- Bühlmann ZH-L16 — Most widely used decompression algorithm in dive computers. See Bühlmann tables.
C-D
- CMAS — World Underwater Federation. International body recognizing FFESSM certifications.
- DCS (FR: ADD) — Decompression Sickness. Nitrogen bubble formation in tissues from ascending too quickly. Treatment: oxygen therapy + hyperbaric chamber.
- Decompression stop (FR: Palier) — Mandatory pause at fixed depth (3m, 6m, 9m) during ascent for off-gassing. Calculated by tables or computer.
E-G
- EAD (FR: PEA) — Equivalent Air Depth. Air depth giving same nitrogen loading as a Nitrox mix. See Nitrox calculator.
- FFESSM — French Federation of Underwater Studies and Sports. Main training body in France. See FFESSM levels.
- Gradient Factors (GF) — Parameters adjusting Bühlmann conservatism (GF Low/High). Technical standard: GF 30/85.
H-N
- Heliox (FR: Héliox) — Helium-oxygen mixture for deep diving. Avoids nitrogen narcosis. Covered by MT2019 Annex 2.
- Henry's Law — Gas dissolved in liquid is proportional to pressure. Foundation of decompression. See gas laws.
- MOD — Maximum Operating Depth for a given Nitrox mix based on max ppO₂ (1.6 bar). See calculator.
- Narcosis (FR: Narcose) — Narcotic effect of nitrogen under pressure. Appears around 30-40m on air. Also called "rapture of the deep."
- Nitrox — Oxygen-enriched air (>21% O₂). Reduces nitrogen loading but limits max depth. See Nitrox calculator.
O-Z
- ppO₂ — Partial Pressure of Oxygen. Must not exceed 1.6 bar (diving) or 1.4 bar (recommended). See Dalton's Law.
- Pulmonary overexpansion (FR: Surpression pulmonaire) — Severe injury from holding breath on ascent. Expanding air (Boyle's Law) tears alveoli → arterial gas embolism.
- SAC / RMV — Surface Air Consumption / Respiratory Minute Volume. Air consumption at surface pressure. Average: 15-20 L/min. See calculator.
- SDG (FR: GPS) — Successive Dive Group. Letter (A-P) indicating residual nitrogen after a dive.
- Trimix — Oxygen-nitrogen-helium mixture for deep diving. Combines Nitrox (less N₂) and Heliox (less narcosis) benefits.
- Valsalva maneuver — Equalization technique: exhale against pinched nostrils to equalize middle ear pressure.