Diving hand signals

In short

Underwater, you cannot talk: you communicate with hand signals. About a dozen essential signals, known by all divers, are enough to say that everything is fine, that there is a problem, that you need to ascend or that you are short of air. Practices vary slightly between training agencies and regions: agree on them at the briefing. Above all, a signal always calls for an answer.

Why it matters

Communication is what links the members of a dive team. A problem signalled early, and understood, is almost always easy to solve: a leaking mask, an ear that will not clear, reaching the reserve pressure. A signal that is badly made, misunderstood or left unanswered lets the problem grow. Knowing and practising the signals is part of basic safety.

Basic rules

• Get attention before signalling: look at your buddy, touch them lightly if needed, or tap your cylinder.
• Face them, at arm's length, hand clearly visible, in front of your mask or chest.
• Make clear, slow signals, and repeat them if necessary.
• A signal calls for an answer: reply "OK" to show you have understood, or with the appropriate signal. If there is no answer, signal again or go and check.
• When in doubt, end the dive safely rather than carrying on without understanding each other.

Essential signals

These signals are described as they are most often used; check them at the briefing.

Signal	Usual gesture	Expected answer
OK (question or answer)	Thumb and index finger form a circle, other fingers straight	"OK" or the problem signal
Something is wrong	Flat hand, palm down, rocking from side to side, then pointing to the cause	Move closer, help
Go up	Closed fist, thumb up	"OK", then ascend together
Go down	Closed fist, thumb down	"OK"
Stop / stay here	Flat hand, palm facing the other diver	"OK"
Reserve reached	Closed fist shown in front of the mask or chest	"OK", adapt the dive
Out of air	Flat hand moving across the throat	Provide the alternate air source at once
Share air	Hand pointing to one's mouth then to the other's regulator	Give the alternate second stage
Safety stop	Flat horizontal hand, fingers of the other hand underneath to show the minutes	"OK"
Breathless	Open hand moving up and down in front of the chest	Stop exertion, help to breathe calmly
Cold	Arms crossed, hands rubbing the shoulders	Cut the dive short
Ear problem	Index finger pointing to the ear	Ascend a little, equalise gently

"Something is wrong", "out of air" and "breathless" have priority: answer them immediately.

Additional signals

• Remaining pressure: show the pressure read on your gauge with agreed numbers (fingers, tens or hundreds of bar depending on practice), or show your gauge.
• Numbers: different conventions exist for counting with one hand; agree on one.
• Direction: a flat hand pointing the way to go.
• Look: index and middle fingers pointed at your eyes, then at what to look at.
• Stay together: two index fingers side by side.
• You / me: index finger pointing to the other diver or to yourself.
• Marine life: many descriptive gestures refer to animals (a hand like a fin for a shark, wriggling fingers for an octopus). They vary a lot: present them at the briefing if the guide intends to use them.

Differences between agencies and local practice

The essential signals are similar from one training agency to another (federations, international agencies), but some differ: the reserve signal, how to show pressure or numbers, some marine life signals. A diver trained elsewhere may therefore misread a gesture. The rule is simple: at the briefing, the guide reviews the signals they will use, and everyone asks their questions.

Practising

• Review the signals before getting back into diving and practise them with your buddy at the start of the dive.
• Practise the "out of air" then "share air" sequence in a pool or in shallow water, with an instructor.
• With thick gloves, some signals are hard to read: exaggerate them.

Key takeaways

• A signal always calls for an answer.
• Face your buddy, hand visible, clear and slow gestures.
• "Something is wrong", "out of air" and "breathless" have priority.
• Practices vary: agree on them at the briefing.
• When in doubt, end the dive safely.

Further reading

The guide on surface and night communication presents the signals visible from the boat and those made with a light; the air management guide details what to do after an "out of air" signal. An illustrated chart of the signals is planned: it will be added as a gallery from the guide image library, with alternative text describing each gesture.