Hand signals divers and snorkelers use underwater

Underwater, speech does not carry, and a mask or regulator makes it hard to talk even at the surface. Divers and snorkelers therefore rely on hand signals to ask questions, report problems, and point out things of interest. A small, shared set of signals prevents confusion, but only if both people know what each one means before they enter the water.

Signals are not fully standardized. Training agencies, dive operators, and regions teach slightly different versions, so the most useful signal is the one you and your buddy have both agreed to use. The examples below are widely used, but confirm them with your instructor before you rely on them.

Signals for air, cold and problems

Several signals appear in most training courses and are worth learning first:

• OK: Form a circle with the thumb and index finger, with the other fingers extended. Use it as a question, "Are you OK?", and as the answer.
• Out of air: Draw a flat hand across the throat. This signal means you need air, and your buddy should respond by offering an alternate air source.
• Low air: Make a fist and hold it against your chest, then show your pressure gauge if your buddy needs the reading.
• Cold: Wrap your arms around your body and shiver to show you are cold and want to end or shorten the dive.
• Something is wrong: Hold a flat hand out and rock it side to side, then point to the item that has the problem, such as your mask or regulator.

Agencies and operators sometimes teach variations of these signals, so confirm each one with your buddy before the dive. Both divers should also watch their gauges regularly, because a low-air signal may come too late if one person checks air only after the other is already low.

A signal that goes unanswered should be repeated, not assumed. If your buddy does not respond to an OK question, repeat the signal and wait. If the message is still unclear, end the dive together, following the plan you agreed before entry.

Signals for direction, depth and the surface

Thumbs up means ascend, and thumbs down means descend. Underwater, a thumbs-up must never be used to mean OK, since it tells your buddy to go up or end the dive. Beginners often confuse the two, so keep the circle for OK and reserve the thumb signals for direction. Confirm any thumb signal when visibility is poor and the message matters.

Signal before each change in depth, even a short one. Changing depth without telling your buddy is one of the easier ways for a pair to separate in poor visibility.

To show where to go, point with the index finger in the direction you want to travel, then use a beckoning motion to indicate "follow me" or "come here." To draw attention to something interesting, such as a turtle or a nudibranch, place two fingers at your own eyes and then point toward the object. This signal lets you share a sighting without touching the animal or crowding it.

In a guided group, follow the guide's signals and pass them on to your buddy, so the group moves together.

At the surface, the OK signal is often given with a hand held on top of the head, or with both arms forming an O overhead, so that it can be seen from a boat or the shore. Waving one or both arms overhead is the distress signal. It asks the boat crew or the shore for help, so reserve it for a real need. Make surface signals large and slow so that a boat crew or someone on the shore can read them from a distance.

Confirming signals with your buddy

A signal works only when the other person understands it, and signals work in both directions, so pay as much attention to the signals you receive as to the ones you give. Confirm each important signal by repeating it back, and use the OK signal to show that you have understood and are fine. If you are unsure what a signal means, do not guess: ask again with the OK question and wait for a clear answer before you continue. Keep the set small and memorable, and add a new signal only when both of you agree on it, because an unfamiliar signal in the middle of a dive invites misunderstanding.

Before entry, run a short check on the surface. Ask each other the OK question and answer it, then show the out-of-air, low-air, cold and something-is-wrong signals so both of you know the other can read them. Practice on the boat or the beach rather than trying to remember a long list underwater, and review any differences from your training agency's set with your instructor before you enter the water. Repeat this check at the start of each day of diving, since a signal agreed on earlier may be forgotten by the time you are back in the water. Clear signals help during the dive only if you keep your buddy in view and treat any unclear message as a question to answer before you move on.