Want to make a scuba diver cringe? Just throw a few questionable diving terms into your next conversation: goggles, flippers, or oxygen tank are good ones that will raise a few eyebrows.

Journalists, travel bloggers, friends and family, scuba students…take note. Here’s how to properly speak scuba.

Scuba terminology – what to say

Never say: oxygen
Say: air or breathing gas
Asking a diver, “how much oxygen do you breathe” is a dead giveaway you know zero about scuba diving. Divers use air, or breathing gas. Technical divers might use trimix, and certified Enriched Air Divers sometimes refer to their breathing gas as nitrox.

Never say: oxygen tank
Say: scuba tank or cylinder
As every certified diver knows, the air we breathe here on earth is only 21 percent oxygen. So it’s incorrect to say a diver breathes from an oxygen tank. The correct scuba gear terms are air tank, scuba tank, bottle, or cylinder. The only time a diver might breathe from a tank containing pure oxygen is at the surface following an emergency.

A close-up of a scuba diver's fins, which is the correct scuba terminology to use instead of saying flippers

Never say: flippers
Say: fins
Scuba divers and freedivers wear fins, not flippers. Fins come in many shapes and sizes and are an essential part of any diver’s kit.

The word flipper can refer to:

  • a cooking utensil
  • an appendage marine animals and mermaids have
  • a famous dolphin

…but never the equipment divers wear over their feet.

Never say: goggles
Say: mask
Swimmers wear goggles. Scuba divers use masks specifically made for exploring underwater at depth.

  • Scuba mask lenses are also made of tempered glass or other strong composite materials that can handle intense pressure. This is why you don’t want to use a snorkeling mask when diving.
  • Unlike swim goggles, scuba masks have a wide field of vision and an enclosed nose pocket which enables them to get rid of any water that leaks in (the official scuba terminology is mask clearing).
A diver exiting the water wearing a scuba mask, which is specifically designed for scuba diving

Here’s a mini dictionary of scuba diving terms

BC or BCD = a buoyancy control device

A scuba BCD is basically a vest with an air bladder. BCDs are designed to help divers achieve neutral buoyancy underwater by adding or removing air to the bladder.

C-Card = certification card

Certified divers receive a scuba diving license known as a c-card. This plastic or electronic scuba certification card includes the diver’s photo, certification level, course completion date, and certifying instructor. If the diver completed scuba refresher training, such as PADI ReActivate, there may be a sticker or other information documenting the completion date of that activity.

DAN = Divers Alert Network

When divers talk about DAN and PADI, they’re not talking about a guy named Dan and a lady named Patricia. Divers Alert Network, known as DAN, is an important member of the diving industry. DAN promotes safe diving through research and education. They also offer dive accident and travel insurance. PADI, the Professional Association of Diving Instructors, is the world’s leading dive training organization.

Divemaster vs. Master Diver vs. Master Scuba Diver

You may have heard someone say, “my friend is a master diver.” They’re probably talking about someone who is either a PADI Master Scuba Diver or PADI Divemaster. PADI does not have a master diver rating (but the United States Navy does).

A Divemaster assists with scuba diving courses and leads guided dives. Every instructor was once a Divemaster. Some Divemasters are also PADI Master Scuba Divers, but they’re two different achievements.


Gas narcosis, nitrogen narcosis, or just being narked are diving terms for the phenomenon which affects divers when they dive deeper, causing them to feel anything from euphoric to anxious.

Open Water

When people say they want to become a diver or learn to scuba dive, what they’re describing is the Open Water Diver course. An Open Water Diver certification allows you to dive on your own with another certified diver.

It’s slightly confusing because there is a PADI Scuba Diver course. PADI Scuba Divers may only dive under the direct supervision of a PADI Professional to a maximum depth of 12 meters/40 feet. Learn more about the difference between PADI Scuba Diver and PADI Open Water Diver.

Regulator, Octopus and DV

You may have to listen closely to know whether a diver is talking about a cephalopod or their dive gear. Assuming the latter, you might hear these diving terms mentioned when talking about the equipment which supplies air from a diver’s scuba tank:

  • Regulator – describes the entire set-up (hoses and all), but might also be used to refer to just the second stage (the bit with the mouthpiece). Divers often call them regs for short.
  • Octopus or ‘octo’ – while occasionally used to describe the collection of connecting hoses (hence the name), it more commonly means the back-up hose and second stage that’s often yellow and reserved for emergency use – also known as an alternate air source.
  • Demand Valve (DV) – another word for the second stage. So-called because it provides breathing gas on demand to the diver as they breathe in and out.
A scuba diver setting up a set of regulators, who might use diving terms such as octopus or demand valve to describe them

The Bends

A nickname for Decompression Sickness (a form of DCI), a dangerous condition in which dissolved gases, typically nitrogen, form bubbles in the blood or tissues. It’s usually caused by rapid pressure changes and is why divers must ascend slowly – to avoid getting ‘bent’.


When a diver says how good the ‘vis’ was, they’re using scuba diving slang to refer to the visibility on their dive. Or in other words, how clear the water is and how far away they could see.

And finally, a note on grammar

Whether to say dived or dove is a big debate in the diving community, but the simple answer is that both are correct depending on if you’re speaking American or British English.

Two scuba divers underwater who could say they either dived or dove together, as both diving words are grammatically correct

Now you know a few basics of speaking scuba and getting your diving terms and definitions right. But, if you have more questions, the PADI Open Water Diver course is a great place to find answers — check out eLearning or contact a local PADI Dive Shop to get started.

Related Reading

How to Avoid Looking Like a New Diver
How to Become a Scuba Diver, Everything You Want to Know
5 Things Our Non-Diving Friends Ask Us

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