Scuba Glossary: Q - R - S


Rebreather  –  A closed-circuit system which filters exhaled air, then recirculates it for rebreathing by the diver; requires special training and maintenance.

Recreational scuba diving  –  Diving to prescribed limits, including a depth no greater than 130 fsw, using only compressed air, and never requiring a decompression stop.

Regulator  –  In scuba, any device that changes air pressure from one level to a lower level.

Repetitive Dive  –  Any dive whose profile is affected by a previous dive is considered repetitive.

Residual Nitrogen Time  –  The time it would take to off-gas any extra nitrogen remaining after a dive. Residual Nitrogen Time is always taken into consideration when determining the safe duration for any repetitive dive.

Reverse squeeze  –  Pain or discomfort in enclosed space (e.g., sinuses, middle ear, inside mask) on ascent from a dive.

Rip Current  –  A strong current of limited area flowing outward from the shore, and may be visible as a band of agitated water with the regular wave pattern altered; current is caused by the rush of escaping water which is piled between shore and bar or reef by wave action through a gap in the bar or reef; such currents are dangerous to the uninitiated and are the cause of many drowning’s at ocean beaches; however, when located by divers they are often used to facilitate entry to areas beyond the bar or reef.

Rule of Thirds  –  An air management technique. Use a third of the tank to get to your destination, a third to get back, and the last third belongs to your buddy in case of an emergency.


Safety Stop  –  On ascent from a dive, a specified time spent at a specified depth, for purposes of nitrogen off gassing. By definition it is not a mandatory for a safe ascent from a dive.

Salinity  –  The amount of salt dissolved in a liquid, measured in parts per million.

SASY/SASA  –  Supplied Air Snorkeling for Youth/Supplied Air Snorkeling for Adults. BC-like PFD mounted with small compressed air cylinder and regulator that allows snorkeler to breathe comfortably on the surface but prohibits him from descending. SPG submersible pressure gauge. Required scuba gear that displays the amount of air pressure in the scuba cylinder; can be either analog or digital.

Saturation  –  The degree to which a gas is dissolved in the blood or tissues, full saturation occurs when the pressure of gas dissolved in the blood or tissues is the same as the surrounding pressure of that gas.

Saturation Diving  –  Diving performed after the body is fully saturated with nitrogen. To become fully saturated the diver must stay under water for a much longer period than is allowed in recreational scuba diving tables.

SCR  –  Surface consumption rate. Measure used in calculations for determining air consumption rate at various depths.

SCUBA  –  Acronym meaning Self Contained Underwater Breathing Apparatus.

Scuba Resort  –  A place providing recreation and entertainment to vacationers with the main attraction as that of scuba diving. It may include training, Beach and/or boat diving and many specialties such as wall, drift, wreck, eco-diving and many others. It can be an All-Inclusive, a Live Aboard and or a land base operation. It will normally be supported by one or many of the training agencies.

SDI  –  Scuba Diving International. The recreational scuba training and certification arm of TDI.

Sea Level  –  The altitude of the world’s oceans; all oceans are at sea level.

Second Stage Regulator  –  The regulator that follows, in line, the first stage regulator, and delivers compressed air to the diver. Usually associated with the mouthpiece.

Shallow Water Blackout  –  A sudden unconsciousness, from hypoxia, that occurs among some breath hold dives. Often occurs near the surface after a deeper dive, hence “Shallow Water”.

Shivering  –  The body’s attempt to create heat through muscular activity.

Side Mount  –  A method of attaching tanks to the divers side, technical diving & Cave diving

Sinuses  –  Air spaces within the skull that are in contact with ambient pressure through openings into the back of the nasal passages.

Skin Diving  –  Another name for breath-hold diving; diving without the use of a breathing equipment (may include a snorkel).

SLAM  –  Scuba Lifesaving and Accident Management. YMCA diver rescue course.

SNUBA  –  A surface-supplied compressed air apparatus, for use in shallow diving in calm waters. The air is delivered to one or more divers through a long hose.

Solo Diving  –  Solo diving is the practice of scuba diving alone without a “dive buddy”. Solo diving, once discouraged, is now beginning to gain acceptance among experienced divers who have skills in self-sufficiency and redundant backup equipment.

Squeeze  –  Pain or discomfort in an enclosed (sinuses, Middle ear, inside a mask), caused by shrinkage of that space, occurs on decent.

SSI –  Scuba Schools International

Starboard  –  Nautical terms which refer to the right sides of a ship as perceived by a person on board facing the bow (front). In lay terms, when standing on the bridge of a ship (or any watercraft) looking toward the front of the ship, starboard refers to the right side of the ship.

Stern  –  The back end of a boat.

Submarine  –  A heavy walled vessel that can withstand pressures under water and allow occupants to breath air at sea level pressures and travels under its own power.

Submersible Pressure Gauge  –  Gauge to monitor air supply during the course of a dive.

Super saturation  –  An unstable situation where the pressure of a gas dissolved in the blood or tissues is higher than the ambient pressure of that gas.

Surface Interval  –  Length of time on the surface, usually out of the water, between two consecutive dives.

Surface supplied compressed air diving  –  Diving with the air continuously supplied by a compressor on the surface can be used for both sport and professional diving.

All content provided on this “Scuba Diving Resource” blogs or website is for informational purposes only. Any comments, opinions that may be found here at Scuba Diving Resource are the express opinions and or the property of their individual authors.
Scuba Diving Resource makes no representations as to the accuracy or completeness of any information on this site or found by following any link on this site. Please note that regulations and information can change at any time.

Powered By
Skip to toolbar