ppHe: Partial Pressure of Helium
ppN2: Partial Pressure of Nitrogen
ppO2: Partial Pressure of Oxygen
psi: pounds per square inch
PTC: Personal Transfer Capsule
RD: Rescue Diver
RDP: Recreational Dive Planner
RG: Repetitive Group
RHIB: Rigid-Hulled Inflatable Boat
RIB: Rigid Inflatable Boat
RMV: Respiratory Minute Volume
RNLI: Royal National Lifeboat Institution
RNPL: Royal Naval Physiological Laboratory
RNT: Residual Nitrogen Time
ROV: Remotely Operated Vehicle
RSTC: Recreational Scuba Training Committee
RYA: Royal Yachting Association
SAA: Sub-Aqua Association
SAC: Surface Air Consumption
SAELO: Supply Activated Exhaust Cut-Off Valve
SAR: Search and Rescue
SAUU: South African Underwater Union
SCBA: Self-Contained Breathing Apparatus
SCOR: Scientific Committee on Oceanic Research
SCUBA: self-contained underwater breathing apparatus
SDC: Skill Development Course
SDC: Submersible Decompression Chamber
SDI: Scuba Diving International
SEAL: Sea-Air-Land Teams
SEBA: Submarine Escape Breathing Apparatus
SGA: Siebe Gorman Amphibian
SI: surface interval
SIT: surface interval time
SLAM: Scuba Lifesaving Accident Management
SLJ: Surface Life Jacket
SMB: Surface Marker Buoy
SNUBA: Snorkeling SCUBA
SNUBA: Surface Nexus Underwater Breathing Apparatus
SOB: Same Ocean Buddy
SPG: Submersible Pressure Gauge