What does SCUBA stand for? (Plus other diving acronyms)

The word scuba is one of the rare cases where an acronym has been converted into an actual word that you can play on a Scrabble board.

The acronym S.C.U.B.A stands for Self-Contained Underwater Breathing Apparatus, and was coined by Dr Christian Lambertsen in 1954 – a new name for his earlier invention, the Lambertsen Amphibious Respiratory Unit (LARU).

The History of Scuba Diving

While Dr Lambertsen was a pioneer of the diving world, humans had been finding innovative ways to breathe underwater for centuries.

Our early ancestors likely used hollow reeds as snorkels and two centuries ago we know of people venturing underwater with the aid of inflated animal bladders – yum!

Illustrations lend to the story that Alexander the Great descended into the sea with a bathysphere – an early version of a diving bell – however it is told that he also saw undersea monsters and dragons so… take that with a pinch of salt.

The 16^th and 17^th century saw diving bells growing in prevalence – used for scavenging and dock work and by the time Dr. Edmond Halley refined the concept just before the turn of the 18^th century, enabling adventurous souls to stay underwater for up to 4 hours.

As genius as it was, the bell was incredibly limiting when it came to movement, and thus the Standard Diving Dress (also known as “SDD” – if you like diving acronyms be sure to check out the last section on this page) was invented.

This copper helmet and suit may seem incredibly restrictive today, but back then it was pure freedom.

Closed Circuit

The closed-circuit scuba circulates out the diver’s carbon dioxide and filters unused oxygen back into the system.

This is achieved because the human body actually consumes and metabolizes only a small fraction of inhaled oxygen. The rebreather’s job is to recycle exhaled gases, while constantly replenishing from an oxygen-rich environment - like a tank.

The first commercial scuba rebreather was designed and built in 1878 by Englishman, Henry Fleuss and was developed for many decades to come, including by the aforementioned Dr Christian Lambertsen for the US Navy.

As it turns out, the closed circuit system’s lack of bubbles was ideal for underwater warfare.

Open Circuit Scuba System

In parallel progress was being made on an open-circuit scuba system. Designed in 1925, this system allowed divers’ exhaled gas to be released directly into the water. It was the more popular option with recreational divers as they were easier to use and safer.

What made this system possible was the invention of the demand regulator. This mechanism conserved air supply by only providing oxygen when the outlet pressure was reduced as the diver inhaled.

However, this system was not completely free for divers as it still required a steady air supply from the surface.

The first open-circuit scuba system was inspired by a simple ambient pressure supply valve apparatus. This was hooked up to a 0.7 gallon tank with air compressed to 2,100 psi, 150 bar.

This template had its issues as air was continuously supplied through the mouthpiece and let out via a short exhaust tube, which didn’t have a demand regulator, severely limiting use of the device.

Then in 1942, Jacques Cousteau (the man whose films introduced the underwater world to the masses) and Émile Gagnan designed the first successful and safe open-circuit scuba, known as the Aqua-Lung.

The new Aqua-Lung’s system combined an improved demand regulator with high-pressure air tanks. In 1957, a modified version of the Aqua-Lung broke the world record by reaching a depth of 330ft.

Introducing SCUBA

While Dr Lambertsen invented an underwater free-swimming oxygen rebreather that he would go on to patent and call SCUBA in the 1950s – Cousteau and Gagnan’s diving pressure regulator is truly the forefather of the modern scuba system.

Now that we know a little about where the word ‘scuba’ came from, here are some more acronyms used in the diving world.

Glossary of Scuba Diving Acronyms and Jargon

While diving has become a lot more of a mainstream activity, it’s still a specialized hobby that requires training.

And with any new hobby, or in our case, lifestyle, there are terms unique to diving. Here’s our top list of diving acronyms and jargon to help you speak the lingo.

AAS – Alternate Air Source, also referred to as alternative breathing gas source, this is your second supply unit in case of an emergency.

ABCABS – If you encountering an emergency underwater, you need to follow these steps: Assess the scene for unknown dangers to yourself and patient, Apply Barriers, and check if Airways are open, check if Breathing is normal, if not alert EMS, then do Chest compressions, by now Airways should be open, check Breathing of patient and continue CPR. Finally check for Serious bleeding, as well as Spinal Injury and Shock. Piece of cake, right?

ACD – Automatic-Closure Device seals the regulator’s inlet. They keep water and contaminants out of the regulator's first stage during rinsing and storage, and are pretty commonplace on higher end regulators.

AED – Automated External Defibrillator. Most people would know this term from hospital TV dramas featuring doctors who look like models. An AED is the electronic device used to shock the heart to get it pumping again after life-threatening cardiac events.

ADT – Actual Dive Time is the calculated dive time underwater as well as depth.

AGE – Arterial Gas Embolism occurs when someone has suffered a blood vessel blockage. This is caused by bubbles, lung over-expansion injury, and decompressions.

BCD – Buoyancy Control Device, or Buoyancy Compensation Device, is the jacket that keeps divers positively buoyant on the surface or neutrally buoyant underwater.

BWRAF – BCD, Weights, Releases, Air, Final OK, is the pre-safety check you need to go through before every dive.

CCR – Closed Circuit Rebreather is, as mentioned above, one of the diving systems.

CESA – Controlled Emergency Swimming Ascent is the emergency skill practiced during the open water course on how to ascend to the surface safely.

DIN – Deutsche Industry Norm is the valve system that requires the regulator to be directly screwed into the tank value as opposed to being clamped on. The same as a yoke valve.

DM – this isn’t about messages slipping into your Facebook inbox, it stands for for DiveMaster who is one qualification below an instructor.

DMT/DMC – DiveMaster Trainee/DiveMaster Candidate, those training for the role.

DPV – Diver Propulsion Vehicle is an underwater device that help divers scoot through the water without kicking.

DSD – Discover Scuba Diving, also known as “try diving”. This is when a diver can try diving without doing a license first, under the close supervision of an instructor.

EANx – Enriched Air Nitrox (percentage of O²), this refers to the gas mixture in the tank, which is normally 21%O² and 79%N².

EFR – Emergency First Response, as part of the rescue course, divers are required to take a basic first aid course.

IDC – Instructor Development Course, when you have completed your DiveMaster program, you can train to become an instructor by completing the IDC.

LPI – Low-Pressure Inflator, to inflate BCD, divers are required to connect a low-pressure hose from the tank to BCD, which then inflates.

MOD – Maximum Operating Depth, is the deepest depth divers can safely operate to.

NDL – No Decompression Limit is the time limit a diver has to adhere to at a certain depth to keep Nitrogen absorption at safe levels.

OW – Open Water, the first level diving certification where a diver can dive without professional supervision.

RDP – Recreational Dive Planner, this is a decompression table in which you can calculate no-stop dive time under water.

RNT – Residual Nitrogen Time, is how much Nitrogen is left in the body after multiple dives to certain depths and durations.

SD – Scuba Diver, this is a certification where professional supervision is required while diving.

SPG – Submersible Pressure Gauge, one of the most important for last, this gauge will show you how much pressure remains in your tank.

So what do you think? Did we miss any diving acronyms?

If you have anything to add to the list, feel free to drop us a line.