Scuba Diving Acronyms – Top 14 That Every Diver Needs To Know

2. PADI, NAUI, and SSI: Diving Certification Organizations

These are some of the primary agencies that offer scuba certification and training programs:

• PADI: Professional Association of Diving Instructors is one of the world’s largest diving organizations and offers widely recognized certifications.
• NAUI: National Association of Underwater Instructors emphasizes safety and skills in its certification courses.
• SSI: Scuba Schools International is another global agency providing certification and specialized training programs.

ActionQuest Summer Adventures for Teens, a long-standing PADI affiliate, has certifies over 1,300 scuba divers annually and is recognized as the longest-running teen summer camp for scuba instruction, frequently earning PADI awards for excellence.

3. DAN: Divers Alert Network

DAN is an organization that provides dive safety resources, emergency assistance, and insurance for divers. Many divers become members for access to DAN’s medical and emergency support, especially when traveling.

4. OW, AOW, and DM: Open Water, Advanced Open Water, and Divemaster

These acronyms refer to levels of scuba certification:

• OW: Open Water is the entry-level certification, allowing divers to go to a depth of 60 feet (18 meters) under supervision. ActionQuest offers teens this scuba certification during the Vega Voyage and Polaris Voyage.
• AOW: Advanced Open Water certification allows divers to go deeper (up to 100 feet/30 meters) and often includes training for underwater navigation and specialty dives. ActionQuest offers teens this scuba certification during the Neptune Voyage, Carina Voyage, Barracuda Voyage, and Aquarius Voyage.
• DM: Divemaster certification is a professional-level qualification that enables divers to guide others and assist instructors. ActionQuest offers an internship Divemaster Voyage for students who qualify.

5. BCD: Buoyancy Control Device

A BCD or BC (Buoyancy Control) is a jacket or wing-like piece of equipment that helps divers control their buoyancy. It allows you to float, hover, or sink by adjusting the amount of air in the device. BCDs have an inflator button and and as many as three or more “dump” or “release” valves, enabling the diver to achieve neutral buoyancy and move comfortably through the water.

6. CESA: Controlled Emergency Swimming Ascent

A CESA is another scuba diving acronym that every diver should know. A CESA is an emergency ascent method where a diver swims to the surface while slowly exhaling to release expanding air. This technique is used when a diver has run out of air and cannot access a buddy’s alternate air source. Practicing a CESA is an essential skill taught in entry-level courses, as it helps prepare divers for unexpected situations. At ActionQuest, teen scuba divers learn this skill during their Open Water (OW) training, then practice it as part of a “scuba tune-up” at the beinging of any Advanced Diving Voyage

7. SI: Surface Interval

The SI, or Surface Interval, is the amount of time a diver spends on the surface between dives. It’s crucial for nitrogen release from the body after each dive. Longer SIs reduce nitrogen levels, which reduces the risk of decompression illness or decompression sickness. Divers often use a dive computer or tables to track SIs and determine safe dive times.

8. DCI / DCS: Decompression Illness and Decompression Sickness

DCI (Decompression Illness) and DCS (Decompression Sickness) are both conditions that can affect divers due to the effects of pressure, but they are slightly different in scope and cause:

• Decompression Sickness (DCS) specifically refers to the condition known as “the bends,” which occurs when nitrogen bubbles form in the tissues and bloodstream as a diver ascends too quickly. These bubbles can cause joint pain, dizziness, paralysis, or, in severe cases, death. DCS results from nitrogen absorbed under pressure during a dive not being released gradually enough as pressure decreases.
• Decompression Illness (DCI) is a broader term that encompasses both Decompression Sickness (DCS) and arterial gas embolism (AGE). An AGE can occur if a diver holds their breath while ascending, causing over-expansion of the lungs and forcing air bubbles into the bloodstream, which can then lodge in arteries, leading to serious health risks like stroke or heart attack.

In short, DCI covers all pressure-related injuries from a dive, including DCS and AGE, while DCS specifically refers to nitrogen-related bubble formation due to improper decompression.

9. NDL: No-Decompression Limit

The NDL is the maximum time a diver can stay at a given depth without needing to complete a decompression stop on the way back to the surface. The NDL varies depending on depth; the deeper you go, the shorter your NDL. Dive computers and RDPs (Recreational Dive Planners) are designed to track NDLs, helping divers avoid decompression sickness by staying within safe limits. NDL is one of the most important scuba diving acronyms that every diver learns about early in their diver training.

10. RNT: Residual Nitrogen Time

RNT is the amount of nitrogen left in your body from previous dives. This time is factored in when calculating how long you can stay at depth safely on subsequent dives. RNT is especially important for divers doing multiple dives in a day since residual nitrogen can impact your NDL on the next dive.

11. SPG: Submersible Pressure Gauge

An SPG is a vital instrument that shows how much air is left in a diver’s tank. Monitoring this gauge helps divers know when to ascend safely with a proper air reserve, typically starting their ascent with about 500 psi (pounds per square inch) left in the tank. An SPG is often combined with other dive instruments on a console or embedded in a dive computer.

12. SMB: Surface Marker Buoy

An SMB is an inflatable buoy that divers deploy on the surface or from depth to alert boats to their location. SMBs are especially useful during drift dives or in areas with boat traffic, signaling that a diver is ascending and marking the location for their boat crew.

13. RDP: Recreational Dive Planner

The RDP is a table-based tool created by PADI that helps divers calculate NDLs for specific depths and times. It’s a good alternative for those who prefer manual dive planning over dive computers. Understanding how to use the RDP ensures divers can avoid decompression issues even if their technology fails.

14. PSI and BAR: Units for Measuring Pressure

PSI (Pounds per Square Inch) and BAR are two common units for measuring air pressure in tanks. North American divers typically use PSI, while BAR is standard in Europe. Knowing both units is helpful for international travel and working with different equipment.

Whether learning to scuba dive at ActionQuest or any other dive training organization, understanding these scuba diving acronyms will make your dive training easier and safer, preparing you for a lifetime of underwater adventures. Mastering these terms, from BCD to DCS to NDL, will help ensure you’re well-equipped to handle various situations and feel comfortable and confident under the sea. Dive in, keep learning, and remember—safety and knowledge go hand in hand in the underwater world.