A scuba octopus second stage air source.
What is a scuba octopus, why is it yellow, and why is it important in scuba diving? Image: Peter Treadwell / Unsplash

It is mandatory to have an AAS (alternate air source) as part of your scuba diving setup. Ideally, scuba divers will never end up using this backup air source, but we do need it primarily as a source of air for our buddy if they run low on gas, or if something malfunctions with your primary air source. So what is a scuba octopus, and why is it important?

Learn More: SCUBA acronyms we use everyday!

What is an Octopus in Scuba Diving?

You may have come across the term ‘octopus’ before; from your instructor, at a dive equipment store, or maybe while reading this blog! A scuba octopus is the common term to describe your secondary air source backup regulator.

The octopus just an extra second stage regulator, very similar to your primary second stage regulator (the one you put in your mouth during a dive!). However, the scuba octopus is usually yellow in color, with a bright yellow hose too. This allows it to stand out underwater in an emergency situation.

AQUALUNG Leg3nd Octopus

Sherwood Scuba SR2 Octopus

Scubapro R195 Octopus

Some people may opt to go for a more basic regulator as their octopus, compared to their primary source. This is because we assume we will not be using the octopus as frequently as our main regulator that we breathe from.

Scuba Octopus Setup

It is very important where you place your scuba octopus, and its setup. In the PADI Open Water course, we learn that the octopus must be highly visible and easy to reach in case of emergency.

The octopus should sit within the triangle shape of your body, from your chin to both hips. It can be anywhere within this triangle, as long as it is highly visible and easy to pull out. You should never secure the octopus in your BCD pocket or wrap it up intricately with straps.

Your buddy (or yourself if needed), should be able to locate the octopus, pull it out, and breathe from it in seconds. This is the main thing with an octopus setup.

How does a Scuba Octopus work?

An octopus is basically the same as your primary regulator. For this reason, an octopus is also known as a secondary regulator. It works by delivering air (or whatever gas is in your tank) on-demand whenever you inhale from it.

You will breathe from the octopus the same as when you breathe from the primary regulator. You will inhale and exhale into the mouthpiece.

What is a Scuba First Stage?

A scuba first stage is the part that connects your scuba diving tank cylinder to your hoses and regulators. It is the first stage of reducing the high pressured air from the tank. You will attach the first stage to the tank using a DIN valve or a Yoke valve.

Read More: Which is Safer? DIN valve vs. Yoke valve.

What is a Scuba Second Stage?

A scuba second stage are your regulators that you breathe from; your primary regulator and your secondary (or octopus) regulator. It is the second stage of reducing the pressure from your hoses to the ambient (or atmosphere) pressure.

1 bar = 14.5 psi = about 1 atmosphere at sea level.

For example; if you are at sea level at 1 bar of pressure, then the second stage will deliver 1 Bar of pressure when you inhale and breathe from it.

If you are at 10 meters or 32 feet underwater, which is now 2 bar of pressure, then the second stage will deliver 2 Bar of pressure when you inhale and breathe from it.

Read More about Pressure: What is Boyle’s Law in Scuba Diving?

The second stage is important in scuba diving as it makes breathing air from the tank cylinder easy and not strained (as if you were sucking through a very long straw).

Scuba Octopus Holder

A octopus holder is very handy for keeping your regulator and hose in the right position on your equipment, or to keep it from dangling onto the corals during your dive. They are inexpensive and there are quite a few different designs.

Skum-Ball Regulator Mouthpiece Cover

I personally use and love this bauble ball holder, and you can either stick the octopus mouthpiece into the bauble, or you can bend your yellow hose and stick it in there.

It is simple in design and long-lasting as there are no plastic bits that can be damaged.

Please note; you may end up looking like a Christmas tree with a brightly colored bauble!

Magnetic Octopus Hose Holder Clip

I’ve used these types of octopus holders a handful of times, and it is pretty cool.

It’s a powerful magnetic that keeps the octo in place. However, there have been reports that the magnet can interfere with your compass if they are too close to one another. In this case, I would have both items on opposite shoulder straps.

Dive Triple Hose Holder with Clip

This is a simple hose holder and you can configure it into the way that you want.

Depending on your hose width, this clip can be quite tight and difficult which means it is slightly harder to pull out.

However, this does mean your hoses are very secure!

Octopus Retainer and Plug with Clip

This octopus retainer secures around the mouthpiece, rather than the hose. It also comes with a plug that blocks the mouthpiece when it is not in use. This stops sand or debris from entering the regulator.

It is slightly harder to release, so do make sure you and your buddy know how to use it before a dive!

Other Alternate Air Sources

Breathable Power Inflators are quite a new thing in the scuba equipment world. Us, divers love the newest and coolest gadgets, but I do find that we tend to stick to what we know best.

In the PADI Open Water videos that you watch during your course, you may have noticed these power inflators that you can breathe from. In real life, I’ve only seen this perhaps once or twice over hundreds of scuba divers. Breathable power inflators have been adopted very slowly and fairly sparsely.

How it works, is that this power inflator comes with a regulator that you can breathe from. This means there is no bright yellow secondary regulator and yellow long hose on your equipment. This keeps it very streamlined.

In the case of emergency, you will switch from your regular primary regulator to this breathable power inflator. You will then give your primary regulator to your buddy to breathe from.

As the primary regulator’s hose is quite short, you will be very close to your buddy as you ascend. There is also the fact that you will have shared a mouthpiece (from your mouth to your buddy’s), so this is a factor you should consider.

Personally, I’m not a big fan of these breathable power inflators. I prefer the old school way of having a long yellow hose that is easy to remove and use in emergencies! It’s also the method and scuba setup that most people have dived with, which means it is more accessible!

Emma was initially terrified of the deep ocean but dived into scuba diving in 2013, and hasn't looked back since! She worked as an underwater videographer for several years and is now a PADI Master Scuba Diver Trainer. She currently runs a dive shop on the island of Koh Tao in Thailand and is the founder of Down To Scuba.