Justin and Fritz in Sodwana

Communicating underwater

One of the things I love about diving is the silence – the only sounds are your breathing, and the sounds of the underwater world. These could include crackling coral, the sound of parrotfish munching the coral or triggerfish being aggressive, and perhaps boat traffic above. Unless you’re wearing a full face mask (ask Andre about those fabulous devices) you won’t be able to rely on normal speech to make your thoughts and needs known. So what are the options?

Inaudible communication

Hand signals

There are the standard scuba signals that you’ll learn on your Open Water course (OK, I have a problem, up, down, etc), there are fairly standard signals for various kinds of fish (the one for shark being the most obvious!) and then there are the hand signals you’ll invent as you go along. If you have a regular dive buddy, you’ll be surprised how much you can communicate with each other as you figure out a little language between yourselves.

Justin and Fritz in Sodwana
Justin and Fritz chatting at the safety stop in Sodwana

I was highly amused to see in Sodwana that Fritz and Justin the Silver Fox, who are regular dive buddies in Cape Town, chat more underwater than on land. Thanks to his hand signals, the famously taciturn Fritz almost had his own current system swirling around him at the safety stop after our deep dive, as he and Justin discussed the turtles we’d seen and the shark who’d swum by in the distance. The photo above is dodgy because I think I was laughing so much when I took it!


If you’re in an environment where it’s dark enough for a light to be discerned, such as a cave, wreck or on a night dive, you can use your light to get your buddy’s attention. DO NOT shine it in his eyes… I can’t tell you how annoying that is!


Slates are usually white pieces of plastic that you can write on underwater with a pencil, and show to your buddy. This method of communication isn’t ideal for emergencies or for getting someone’s attention at a distance, but they can come in handy… Such as when Tami wrote “SMB?” at me on her slate after a wreck dive on the SAS Pietermaritzburg, while we completed our safety stop.

Audible communication

One of the central tenets of safe recreational scuba diving is to dive in a buddy pair, and buddy awareness is essential. You should be close enough to see your buddy’s face, if not to actually reach out and touch him. Audible signalling devices should thus not be necessary.

In an ideal world of perfect buddies and perfect diving conditions, none of these devices would be necessary. Fact is, they do come in handy, more often than not.


A shaker looks like a sealed test tube made of plastic, with a metal ball inside it. They are marketed under such catchy names as “Aqua Maraca”, which make me want to crawl under a table and hide.

You attach it to your kit somewhere, and shake it to make a loud rattling noise underwater that will hopefully get your buddy’s attention. Just make sure your buddy knows what it sounds like underwater so that he’s not left looking around wondering what that odd noise is, while you get into trouble!

These can be SUPER annoying if you misuse them… I’m just saying!

Signalling devices
Signalling devices, from left to right: shaker, air horn, whistle

Tank bangers

This is nothing more than a large ball or bead on an elastic band that you put over your cylinder. When you want to signal to someone, you reach back and snap the elastic, hopefully causing the bead to bang against the tank. (This is the ideal device for Tony, who LOVES to snap elastics of all kinds.)

This is a very simple device and very easy to make at home, but relies on you positioning it such that you can reach around to it when you need it. If you’re stuck somewhere, or have limited arm dexterity when in a wetsuit, perhaps this isn’t the right choice for you.

You could equally well rap on your cylinder with anything else hard that you have at hand – dive knife, torch, or a well-placed stone if you’re desperate!

Air horns

An air horn attaches to your inflator hose, and works above and below the surface. It’s essentially a pneumatic signalling device that takes a bit of air from your cylinder and uses it to generate a sound. This is probably the quickest of the noise-making signalling devices to use, because you should be very familiar with the location of your inflator button and able to find it by touch.

(Just as an aside, an air horn can be more useful than a whistle above the surface because you don’t need to remove your regulator to use it.)


If you’re quite nearby to someone, you can potentially get their attention by yelling into your regulator. Tony’s Zero to Hero student Kate would often sing classic rock songs to herself while we swam, and when I was buddied with her I could hear her singing. As far as forming actual understandable words… Well, good luck!

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Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

3 thoughts on “Communicating underwater”

  1. RE: Audible comms…..Ok, I will not go into the technical side of FFM’s (Full Face Masks) and wireless underwater comms……
    Here is something you can try if you really need to say something and have mastered your regulator clearing skills….
    Remove a glove and take a deep breath from your reg, put the glove opening over your mouth and blow some air into it (or “pre-fill” it with your octo)….speak into the air-space of the glove…..and do your reg clear….it may surprise you. Hint: (do not exhale when trying to listen due to the bubble noise)

    have fun

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