Scuba Diving Acronyms

Okay. I mean, mnemonics are an easy way to keep score of things, but whaaaaaat? BWRAF, CESA, STELA, whaat?

Us diving instructors LOVE our acronyms when teaching. It is an easy way to help students remember, and for us as well!

Many common scuba acronyms are used within clubs, scuba schools, training agencies, and various online forums that include definitions.

Some of these diving acronyms can also refer to widely known technical terms that may or may not originate from diving.

This article will cover some of the common diving acronyms found in scuba diving circles along with some that are not as widely known.

🤿 1. SCUBA – Self Contained Underwater Breathing Apparatus

First, let’s handle the scuba diving equipment.

Even the word SCUBA is an acronym! Of course, SCUBA stands for Self Contained Underwater Breathing Apparatus.

This refers to your scuba kit strapped to your back consisting of a buoyancy control device, first and second stage, alternate air source, and submersible pressure gauge.

BCD – Buoyancy Control Device

This is the jacket type BCD or back inflated BCD that holds your tank in place and keeps you neutrally buoyant underwater.

Buoyancy control device on water

CCR – Closed Circuit Rebreather

CCR diving is considered part of the technical diving world. You don’t blow bubbles, but the air gets “recycled” back into a closed circuit.

DIN – Deutsche Industry Norm

Mostly used in Europe and in cold water diving, this type of threaded valve system is directly screwed onto the tank, as opposed to yoke clamp valves which are more common.

DPV – Diver Propulsion Vehicle

The underwater scooter! Too lazy to fin? Zip around in this nifty little toy that propels you to wherever you want to go in the dive world.

LPI – Low Pressure Inflator Hose

This is what inflates your BCD. Your first stage pumps high pressure into the low pressure hose and lets you inflate.

SMB – Surface Marker Buoy

Affectionately known as the safety “sausage”, the surface marker buoy is deployed during your safety stop or just before, warning boats of your presence and increasing your visibility.

SPG – Submersible Pressure Gauge

This is the console that tells you what your depth is and how much air you have left in your tank. Some SPGs have compasses.

Submersible pressure gauge

📚 2. Training Agency Acronyms

Now let’s get into the acronyms for scuba diving training agencies.

PADI – Professional Association of Diving Instructors

SSI – Scuba Schools International

NAUI– National Association of Underwater Instructors

BSAC – British Sub Aqua Club (BSAC)

CMAS – Confederation Modiale Des Activites Subaquatiques/The World Underwater Federation

SDI – Scuba Diving International

📖 3. Dive Education Acronyms

During your open water course and advanced open water courses, you might run into a bunch of scuba diving acronyms to help you better remember what you’re supposed to do in the underwater world. Here are a few, remember?

ADT – Actual Dive Time

The actual dive time is exactly what it sounds like – the total time taken on a particular dive.

BWRAF – BCD, Weights, Releases, Air, Final

Remember the buddy check? Check if the BCD is inflating correctly, check weights, releases, the air is on? And final okay.

CESA – Controlled Emergency Swimming Ascent

Remember swimming lengthwise in a pool and saying “ahhhhhh…….” for as long as you can?

The CESA is what is going to get you safely to the surface in an event that you get stuck underwater and have to go up in a hurry.

Since you cannot swim up and hold your breath, saying “ahhhhhh….” on the way up ensures that you are breathing out.

Instructors have to do this for one whole minute!

EANx – Enriched Air Nitrox

This is a recreational diving gas blend that has less nitrogen than a regular compressed air tank.

A regular tank has 21% oxygen and 79% nitrogen while enriched air nitrox blends typically have 32% or 36% oxygen. Less nitrogen, less absorption, more bottom time!

MOD – Maximum Operating Depth

When diving with any blend of compressed air, and especially EANx, you have a maximum operating depth that cannot be exceeded. This is because oxygen is toxic at high pressure and oxygen toxicity is extremely dangerous.

NDL – No Decompression Limit

Either your RDP or your dive computer tells you this. This is the maximum allowed bottom time at a certain depth to avoid going into decompression.

RDP – Recreational Dive Planner

The complicated-looking table is the recreational dive planner that allows you to see what your time limit is for your next dive, which brings us to the RNT.

Instructor discussing the RDP
Source: Professional Association of Diving Instructors (PADI)

RNT – Residual Nitrogen Time

The RNT is the amount of time you have spent at a given depth for a repetitive dive. It calculates how much your residual nitrogen absorption is and how much time you have remaining for future dives.

SI – Surface Interval

This is the boring part where you sit on a boat and wait it out, or on a beach. It is the time necessary for your to off-gas your residual nitrogen and be able to extend your bottom time for future dives.

Surface interval time depends on how much a diver spends underwater throughout repetitive scuba diving days.

SORTED – Signal, Orientate, Regulator, Time, Equalize, Descend

The five point descent! This is the acronym to remember what you’re supposed to do before descent.

  • Signal your buddy that you’re doing down
  • Orientate downwards to see where you are going
  • Check your breathing in the regulator
  • Note the time
  • Equalize and Elevate your low pressure inflator hose
  • Descend!

STELA – Signal, Time, Extend, Look & Listen, Ascend

And of course, the matching five point ascend. STELA is to help remember what you’re supposed to do on your ascent.

  • Signal your buddy
  • Note the time
  • Extend arms
  • Look upwards and listen for traffic
  • Ascend!
Five point ascend training


Remember the symptoms of oxygen toxicity? That happens when you breathe too much oxygen at depth, resulting in the higher atmospheric pressure and O2 concentration.

  • Visual disturbances
  • Ear ringing
  • Nausea
  • Twitching
  • Irritability
  • Dizziness

🏥 4. Dive Education Acronyms

MSDT, OWSI, whaaaaat? Each dive certification level has its own acronyms!

AWARE – Aquatic World Awareness, Responsibility and Education. Project AWARE is a nonprofit organization that focuses on the awareness and education of issues in the ocean. It was founded in 1987.

AOW – Advanced Open Water. The certification level just after the open water. It has 5 modules – two compulsory ones called deep and underwater navigation, and three electives. It’s a fun course!

CD – The Course Director is who teaches and certifies the instructors.

DM – The divemaster program is designed to take divers on the first steps to becoming dive professionals. Divemaster courses typically last several weeks and consist of several on-the-job training days.

DMT – Divemaster Trainee. These poor guys are affectionately at the bottom rung of the ladder, and do everything in a dive operation for the instructors and divemasters. At the same time, of course, they are learning and being coached to become the future professionals.

DSD – Discover Scuba Diving. The “try diving” type course that PADI has to introduce folks to the sport. DSD courses typically consist of a short theory and skills session, followed by two dives to a maximum depth of 12 meters.

Group of scuba divers

IDC – Instructor Development Course is what trains scuba diving instructors. Courses are typically 3 to 4 weeks and covers a comprehensive combination of theory, teaching skills, demonstrations, and water skills.

IE – The Instructor Exam is what instructor candidates take at the end of the IDC. It is long, some of it can be difficult, and it covers 5 different modules which includes dive physiology and physics.

MSD – Master Scuba Diver. MSDs are considered the most elite group of non-professional recreational divers. You’ll need five PADI specialty courses for this, and 50 logged dives.

MSDT – The Master Scuba Diver Trainer is a step up from the OWSI. After you become an instructor, the MSDT course consists of 5 specialty instructor courses that makes you a specialist in those fields.

OW/OWD – Open Water. The basic certification level, a OW or OWD is the open water diver!

OWSI – The Open Water Scuba Instructor is who teaches and certifies scuba divers.

PPB – Peak Performance Buoyancy Course. An elective that is part of the Advanced Open Water Course, the PPB is an extremely useful module that everyone should go for.

🌐 5. Diving Medical Acronyms

Even all the medical conditions have acronyms!

ABC – Airway, Breathing, and Circulation. It is taught in any basic first aid course that this is the first thing you check before administering help.

AED – Automated External Defibrillator is what you run for when someone needs their heart restarted.

AGE – Arterial Gas Embolism. This is what you get when you hold your breath and ascend too quickly. Air expands on the way up, so if you hold your breath, the air in your lungs expand as you shoot up……..well, you get the idea.

CNS – The Central Nervous System is the part of the nervous system in vertebrates that coordinates the activities of the body. It consists of the brain and the spinal cord.

CPR – Cardio Pulmonary Resuscitation. Hopefully, you won’t have to use this, but if so, the EFR course (see below) will teach CPR that consists of rescue breaths and chest compressions.

Learning cardio pulmonary resuscitation
Course: Professional Association of Diving Instructors (PADI)

DCI / DCS – Decompression Illness and Decompression Sickness is what you DON’T want to get. Also called the bends, DCI and DCS are often used interchangeably.

DAN – The Divers Alert Network is an international, nonprofit organization that provides medical emergency services to divers, as well as educational programs and resources on diving safety.

EFR – The Emergency First Response course is an internationally recognized CPR and first aid training program. It’s a requirement for many scuba diving certification organizations in the rescue course.

EMS – Emergency medical services (EMS) is a term used in some countries to refer to the ambulance and emergency health services that provide out-of-hospital acute care and transport to definitive care.

🤔 6. Final Thoughts On Scuba Diving Acronyms

So now you know the lingo, get out there and use it! Scuba divers are always looking for new acronyms to share. Did we miss anything out? Pop a comment below if you think so!

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