Scuba Diving Hand Signals: Chart, Gas Numbers and Night Light Signals

Is there one standard set of diving hand signals?

The closest thing is the Recreational Scuba Training Council's Common Hand Signals for Recreational Scuba Diving, effective 1 December 2005 and approved by IDEA, PADI, PDIC, SDI and SSI. Its authors chose hand motions over finger motions so the signals work in mittens, and borrowed meanings from land gestures so that divers trained by different organisations, or in different languages, can read each other.

It is not universal. The U.S. Navy Diving Manual has its own chart: a clenched fist for stop where RSTC raises a flat palm, and four fingers pointing up for go up where RSTC uses the thumb. France's diving federation, FFESSM, requires every Level 1 diver to perform its own list, which includes signals for half pressure, reserve and being out of breath. The set also grows: PADI introduced an "I don't feel well" signal in 2023. Our training guides show where signals sit in an entry-level course.

Scuba diving hand signals chart

The chart uses the RSTC description as its base and notes where the U.S. Navy chart, SSI's beginner list or other sources differ. Signals that ask a question, like OK, expect the same signal back if the answer is yes, or a different one if something is wrong. RSTC asks for deliberate, clear movements, with a pause between signals so your buddy keeps up.

How to signal gas pressure: bar, psi and digit by digit

This is where divers disagree most. RSTC standardises only two gas signals, low on air and out of air, and treats pointing at a gauge as a natural question meaning "what does it read?". The numbers themselves are left to agencies, regions and dive centres, and DAN's Eric Douglas describes several systems in use side by side.

Units make it worse. SSI tells beginners that the answer to "how much air do you have?" depends on whether the gauge reads bar or psi, and sets its low-on-air point at 50 bar on a metric gauge or 500 psi on an imperial one. Spelled out digit by digit, 2, 0, 0 is a full cylinder in bar and an almost empty one in psi, because 200 psi is about 14 bar.

The simplest fix comes from DAN: many divemasters skip the code and say, "When I point to my gauge, please just show me yours." A gauge shown to your buddy needs no code at all.

Night dive light signals

At a distance the torch beam does the talking. Every source we checked uses a circle for OK. They split on what a straight sweep means, which makes it the signal to settle before a night dive.

PADI and DAN Europe describe quick side-to-side movements as "I have a problem". The U.S. Navy uses large, rapid up-and-down movements with the arm extended for "something is wrong, I require assistance". The cave and technical convention, as IANTD's Phil Short describes it, uses a slow side-to-side slash for attention and a rapid up-and-down slash for emergency. So a sideways sweep reads as trouble to a PADI-trained diver and as "look at me" to a cave diver. SDI's night course keeps it to two light messages at distance, attention or OK and something's wrong, with standard hand signals up close.

Up close, shine the beam on your own hand and make the normal signal. PADI teaches this, and the Navy chart says to use regular hand signals in front of the light. Hold the hand away from your body so it shows against the water, as PADI's Martin Robson suggests, and keep the beam off faces, which both PADI and SDI ask. BSAC adds that complex hand signals do not work as well in the dark. Our night diving basics cover lights, buddy distance and marking the exit.

Surface signals: OK, help and boat pickup

Surface signals have to be read from a boat, so they use whole arms. The finger OK that works at arm's length underwater disappears at a distance.

• OK at a distance: both arms overhead, fingertips touching, making a large O (RSTC). The U.S. Navy uses this far from the pickup boat; close to the boat, its version is one hand raised overhead giving the finger OK.
• OK with one hand busy: one arm overhead, fingertips on top of the head (RSTC). PADI shows divers touching the top of the head after a dive.
• Help: wave a hand quickly from horizontal to overhead, and the hand may strike the water (RSTC). The U.S. Navy files the same wave under "distress or help or pick me up" and says it means immediate aid is required.
• Sound: SDI's night course gives five or more whistle blasts as distress.
• Recall from the boat: BSAC notes that four pulls on an SMB or DSMB line is a widely recognised signal for divers to return to the surface.

Agree the signals in the briefing

Every source says the same thing: go over signals before each dive. RSTC calls it prudent regardless of the experience and knowledge of the divers involved. BSAC asks anyone with an unfamiliar buddy to check they use the same signals or understand the differences, and says all signals should be acknowledged. The U.S. Navy is stricter: a signal must be acknowledged immediately, and failure of a diver to respond to a signal is an emergency.

Skipping this has real costs. DAN's Eric Douglas nearly failed a dive in his instructor exam because the examiner, a cave diver, gave OK as a closed fist, and Douglas never started the skill. Show each other the signals on the boat as part of the dive briefing, then finish with the buddy check. These are the ones worth showing, not only naming:

• OK: the ring, or does anyone use a fist?
• Gas: bar or psi, which number system, and the pressure at which you show low on air.
• Turn and end: who turns the dive, at what pressure, and whether end the dive and go up are the same signal for you.
• Torch: what a side-to-side sweep and an up-and-down sweep mean tonight.
• Surface: how you show OK, how you call the boat for pickup, and the whistle code. RSTC has no separate pickup signal and the Navy's version is the distress wave, so ask the crew.
• Anything new: the I don't feel well signal dates from 2023, so check your buddy knows it.

Common hand signal mistakes

Most mix-ups come from land habits and from signals that share a hand shape.

• Thumbs up for OK. In the RSTC set a thumb up means go up, or I'm going up, and DAN Europe notes that novice divers often get it mixed up. Use the ring for OK.
• Thumbs down for "not good". It means go down. The problem signal is the rocking flat hand.
• Reading every fist the same way. A clenched fist is stop on the U.S. Navy chart, low on air when pulled to the chest and danger when pushed toward something in the RSTC set, OK for one cave-diving examiner in DAN's account, and 50 bar in the fist-and-finger count.
• Rocking when you mean level off. Both signals start from the same flat hand. Rocked on the forearm it says something is wrong; moved slowly back and forth it says stay at this depth.
• Signalling fast and close to the body. RSTC asks for deliberate movements with pauses, and PADI's Martin Robson suggests holding the hand away from you so it stands out against the water.
• Waving at the boat. For divers a waving arm means help (DAN Europe), and on the U.S. Navy chart it is the distress signal. Give the surface OK instead.
• Missing a vague end-the-dive signal. DAN notes that a diver who suddenly feels ill may simply signal to end the dive, because of pain or anxiety. The right response to the illness signal is to return it, end the dive and surface together. Our guide to panic and anxiety underwater covers the early signs.