Underwater communication
0 of 4 hands-on
01 Introduction
Underwater you cannot talk, and a regulator in your mouth makes it worse. Divers use a small set of standard signals, practised until they are second nature. This lesson explains the most common signals and the habits that make communication work.
Objectives
- Describe the common hand signals used by recreational divers
- Explain how divers communicate at the surface and with the boat
- Describe how to attract attention and how to confirm a message has been understood
02 Watch
Talking without words
4 min · Video in production
- 1
A close-up of hands making a series of signals: OK, up, down, stop, look, and low on air.
- 2
Two divers exchanging signals above a reef, with each signal repeated back.
- 3
A diver tapping a cylinder with a metal object to attract attention, then pointing.
- 4
A boat crew and a diver exchanging OK signals at the surface across a stretch of water.
03 Learn
The basic signals
Signals are very similar across training organisations, but they are not identical everywhere. Always agree your signals before the dive, and check the briefing. If you use an unusual signal, show it to your buddy first.
| Signal | How it looks | Meaning |
|---|---|---|
| OK | Thumb and forefinger forming a circle, other fingers raised | I am OK. Are you OK? |
| Thumb up | Thumb pointing up | Go up, or end the dive |
| Thumb down | Thumb pointing down | Go down, or descend |
| Stop | Flat palm held out | Stop, or hold your position |
| Slow down | Flat hand moving up and down slowly | Slow down, or relax |
| Look | Two fingers pointing to the eyes, then at the thing to see | Look at that |
| Low on air | A clenched fist held against the chest | I am low on gas |
| Out of air | A flat hand moved across the throat | I am out of gas and need to share |
| Problem | A flat hand rocking from side to side | Something is wrong |
| Buddy up | Two fingers held together | Stay together |
Predict first
You see your buddy make a flat hand rocking from side to side. What does it mean?
Surface signals
At the surface, divers use larger signals, because the distance is greater and there are waves. An arm raised over the head with the hand on the head means OK. Waving an arm, or blowing a whistle, means help. A raised, bright marker shows the pair's position. Many dive operators brief their own signals, so check the briefing.
Attracting attention
- A light waved in a circle, or aimed at a surface, can catch the eye of a buddy underwater.
- A small metal rattle or a tap of a metal object on a cylinder makes a sound that carries well underwater.
- A whistle or an audible signal attracts attention at the surface.
- Approach your buddy, make eye contact, and then signal clearly. Do not grab or pull them.
Slates and written messages
For anything complicated, a slate and pencil is a good option. Write short, clear messages and show them at eye level. A slate can be used for numbers, such as the gas remaining, or a plan change.
Habits that make signals work
- Make signals slowly, clearly and in the open, and in the line of sight of your buddy.
- Use a light in poor light, so that a signal can be seen.
- Give your buddy time to see and respond, and repeat it if needed.
- Check on each other often with an OK, and confirm any change to the plan.
- Do not use jokes or unclear gestures, which can be mistaken for real signals.
Take a guess first
On a two-person dive, each diver gives an OK check every 2 minutes. How many OK checks does each diver give in a 40 minute dive?
04 Explore
Try it yourself
Match each signal with its meaning.
Match each signal with its meaning.
- Thumb up
- Flat palm held out
- Fist held to chest
- Flat hand across the throat
- Flat hand rocking side to side
05 Apply
Scenario
Midway through a dive, your buddy signals 'low on air' by holding a fist against their chest. You look at your own gauge, which shows plenty. Your buddy looks calm, and you are in the middle of a lovely school of fish.
What is the best response?
06 Check
07 Summary
Key points
- A small set of standard signals covers most needs, and divers agree them before the dive.
- Always answer a signal. A problem or out of gas signal needs an immediate response.
- At the surface, use big signals, a whistle and a marker.
- Use slates, lights and sounds to attract attention, and check in regularly.
Before you apply this in the water
- Have I been trained by a qualified instructor for this?
- Am I medically fit to dive?
- Do I have a buddy and a plan?
- Am I diving within my training and limits?
Answer every question in the Check section to mark this lesson complete.