Scuba Hand Signals Chart
In scuba diving the OK signal is the thumb and forefinger touching in a circle with the other three fingers extended. Thumbs up does NOT mean OK: it means ascend and end the dive, and any diver can call the dive with it. A flat hand drawn across the throat means out of air and is treated as an immediate emergency.
A hand signal is a shared agreement about a gesture, and that is worth stating plainly, because it explains everything else on this page. Signals are not a language with a dictionary somewhere that settles disputes. The core set below is close to universal, but past that they vary by training agency, by region and by individual dive operator, and the place they get agreed is the briefing and the buddy check before the dive.
The reason they matter more than they look is that underwater you lose almost every channel you normally use. Voice through a regulator is mostly noise. Facial expression is behind a mask. Body language is distorted by neoprene and buoyancy. What is left is a set of about twenty gestures, and the discipline to make them large, deliberate and acknowledged.
What are the standard scuba hand signals?
The table gives the signal, how it is made, what it means, and the response the person receiving it is expected to give. That last column is the one usually left out of signal charts, and it is the half that actually prevents accidents: a signal nobody answers is a signal that failed.
| Signal | Group | How it is made | What it means | Expected response |
|---|---|---|---|---|
| OK | Status | Thumb and forefinger touching in a circle, other three fingers up | I am fine, or, is everything fine | Return the same signal. Anything else is treated as a problem |
| OK at distance or on the surface | Status | One arm raised over the head in a circle, or both arms in a circle | I am fine, signalled to a boat or a distant buddy | The boat repeats it back. Do not use the underwater OK on the surface |
| Not OK, problem | Status | Flat hand, palm down, rocked side to side | Something is wrong. Usually followed by pointing at what | Close the distance, ask what, and be ready to end the dive |
| Up, ascend | Direction | Closed fist, thumb pointed up | End the dive and go up. It does NOT mean everything is fine | Acknowledge and ascend together. This is a command, not a question |
| Down, descend | Direction | Closed fist, thumb pointed down | Descend, or continue descending | Acknowledge and descend together at a shared rate |
| Level off, stay here | Direction | Flat hand, palm down, moved horizontally | Hold this depth, stop descending | Level out and acknowledge |
| Stop, hold | Direction | Flat open palm facing the buddy, like a traffic signal | Stop what you are doing right now | Stop immediately, then look for the reason |
| Low on air | Gas | Closed fist held against the centre of the chest | I have reached my reserve. The dive is turning now | Acknowledge, begin the turn or the ascent, stay close |
| Out of air | Gas | Flat hand drawn across the throat | I cannot breathe from my own supply. This is an emergency | Present your alternate air source at once and start a controlled ascent |
| Share air, give me air | Gas | Fingers pointed to the mouth, then hand out toward the buddy | Pass me your alternate second stage | Donate, establish a firm grip on each other, ascend together |
| How much air do you have | Gas | Flat hand held across the palm of the other hand, or two fingers tapped on the palm | Report your remaining pressure | Answer with number signals, or show the buddy your gauge |
| Look, look at that | Attention | Two fingers pointed at your own eyes, then at the object | Direct attention. Almost always a fish rather than a problem | Look, then acknowledge with OK |
| Danger, hazard | Attention | Closed fist held out toward the hazard, or a fist tapped on the palm | There is something here to keep away from | Stop, identify it, and move away as a pair |
| Slow down | Attention | Flat hand, palm down, pushed down slowly two or three times | You are moving, or ascending, too fast | Slow immediately, particularly on an ascent |
| Cold | Comfort | Arms crossed over the chest, hands rubbing the upper arms | I am getting cold. Often the first sign a dive is about to end | Acknowledge and plan to shorten the dive |
| Cramp | Comfort | Both hands with fingers clenched, or pointing at the cramping muscle | I have a cramp, usually in a calf | Steady the buddy, help stretch the fin tip toward the knee |
| Buddy up, stay together | Team | Two index fingers held side by side | Close the distance and stay with me | Move in and hold position within arm reach |
| Which way, where is the boat | Team | Hands held out, palms up, with a shrug, then pointing | I have lost the reference. Which direction | Point the heading, or produce the compass and agree it |
| Boat, exit | Team | Both hands angled together to make a roof shape, or a flat hand over the head | The boat, or the exit point, is over there | Acknowledge and set the heading together |
Why is thumbs up not the same as OK?
Because on land it means good and underwater it means go up, and that difference has ended more dives by accident than any other single gesture. OK is the thumb and forefinger touching in a circle, with the other three fingers extended. Thumbs up means ascend and end the dive. New divers reach for the land habit constantly in their first ten dives, and an instructor who sees a thumb goes up, because that is the only safe way to treat it.
Treating the thumb as absolute is not pedantry, it is the mechanism that makes buddy diving work. Any diver in a team can call the dive, for any reason, and does not have to explain it underwater. A diver who is cold, or narked, or uneasy, or simply not enjoying themselves, will only call a dive if calling it is free of argument. Introduce negotiation at depth and people stop calling dives they should call. The explanation, if there even needs to be one, happens on the boat.
The same logic applies to the OK signal itself. It is a question as often as a statement, and it demands a reply. If you signal OK to a buddy and they do not return it, treat that as a problem and close the distance, even if they look fine. Silence is not agreement.
How do you signal air pressure and numbers?
Number signals are the least standardised part of the whole system, and above five there are several competing conventions in common use. The most widely taught are below, but the practical advice is simpler: for anything that matters, show your buddy the gauge.
| Number | How it is commonly made |
|---|---|
| 1 to 5 | Fingers held up, palm toward the buddy |
| 6 | Thumb and little finger extended, or five fingers then one |
| 7 | Thumb, index and little finger, or five fingers then two |
| 8 | Thumb and two fingers in an L, or five fingers then three |
| 9 | A closed fist rotated, or five fingers then four |
| 10 | Two closed fists tapped together, or ten fingers shown at once |
| Hundreds of psi | The number, then a flat hand, read as hundreds. Five fingers plus a flat hand is 500 psi |
| Bar | Shown in tens of bar. Five fingers then a fist reads as 50 bar |
Handing over a submersible pressure gauge for two seconds transmits the exact number with no ambiguity at all, which is worth more than an elegant signal for 1,700. It also has a useful side effect: both divers look at a real reading rather than a remembered one. On any dive where pressure is going to matter, agree the reporting interval in the briefing, so that the question gets asked on a schedule rather than when somebody happens to think of it. The gas planning calculator gives you the reserve and turn pressure those checks are measured against.
Which signals vary between operators?
More than most charts admit. The table below covers the ones that actually cause confusion, and the fix for every one of them is the same: agree it out loud on the surface, before the dive, with the person you are diving with rather than with divers in general.
| Signal | Why it varies | How to settle it |
|---|---|---|
| Number signals above five | At least three common systems exist and none has won | Agree the system in the buddy check, or show the gauge instead |
| Danger and low on air | Both are made with a closed fist and are easy to confuse at distance | Low on air goes to the chest, danger points outward. Exaggerate both |
| Turn the dive | Some operators use a rotating index finger, others use low on air | Confirm the turn signal in the briefing on any new boat |
| Level off versus slow down | Both are a flat palm down hand, differing only in movement | Make the movement deliberately large, and confirm with OK |
| Something is wrong with my ears | Commonly pointing at the ear, but not universal | Point at the ear, then give the stop or level off signal so intent is unambiguous |
There is also a whole family of local marine life signals, which range from a hand held flat on the forehead for a shark to elaborate operator specific gestures for whatever the site is known for. None of these are safety critical, all of them are fun, and every one of them should come out of the site briefing rather than out of a chart. Guides who dive one site every day have signals for that site, and asking about them before you get in is both safer and more interesting than guessing.
Where do signals actually get agreed?
In the pre-dive briefing and the buddy check, and nowhere else. The briefing covers the site, the plan, the maximum depth and time, the turn condition, the exit, and any signals specific to that operator. The buddy check covers the equipment and, critically, the two things people skip: where your buddy's alternate air source is and how it comes free, and where their weight release is and how it operates.
Add three sentences to that check and most signal failures disappear. Agree how you will call the dive. Agree the turn pressure and how you will report pressure. Agree what you will do if you lose each other, which for recreational diving is normally to search for one minute and then surface. That last one is worth saying out loud even with a buddy you have dived with a hundred times, because the plan only works if both divers do it at the same time. The beginner diving guide walks through the whole sequence.
Anything the standard set cannot carry goes on a folding wrist slate . Headings, depths, turn pressures, the mix and its maximum operating depth, and any message with more than a yes or no answer belong in writing. Miming a complex idea at depth burns gas, invites misinterpretation, and regularly ends with two divers confidently agreeing to two different plans. A pencil settles it in ten seconds. Depth and time limits worth writing down are the ones on the no-decompression limits table.
How do you get attention before you can signal at all?
A signal nobody sees is not a signal, and the most common communication failure underwater is simply that the other diver was looking the other way. Three methods cover almost every case.
Sound. Two taps of a hard object on the cylinder, or a purpose made tank banger, carries well at short range. It is directionally vague underwater, so expect your buddy to look around rather than straight at you. Do not use it constantly, because a signal used for fish sightings stops meaning anything when you need it for a problem.
Light. At night, and in poor visibility during the day, a dive light is the primary signalling tool. Sweep the beam across your buddy's field of view rather than shining it into their eyes, and learn the standard beam signals: a slow circle for OK, a rapid back and forth sweep for attention or a problem. A second light is not optional on a night dive, which the dive light roundup covers.
Touch. At arm's length, a firm touch on a fin, a forearm or a cylinder is normal, expected and by far the most reliable. It is also the method that matters most in an out of gas situation, where the donating diver takes hold of the receiving diver's harness and keeps hold of it through the entire ascent.
One surface signal deserves separate mention because it is not a hand signal at all. A surface marker buoy is how you communicate with the boat, and on a drift dive it is the difference between being collected and being searched for. Deploying one from depth is a trained skill with real entanglement risk, so learn it with an instructor before you need it, and carry it as part of a complete kit like the beginner scuba setup.
Related charts and guides
- Scuba diving for beginners, briefings and buddy checks
- Gas planning calculator, for the turn pressure you signal
- No-decompression limits table, the other number worth writing on a slate
- Best dive lights, for signalling at night and in poor visibility
- Beginner scuba setup, the kit the signals assume
Frequently asked questions
What does thumbs up mean in scuba diving?
Thumbs up means ascend and end the dive. It does not mean everything is fine, which is the single most common mistake new divers make. The signal for fine is the thumb and forefinger touching in a circle. Thumbs up is treated as a command rather than a suggestion: any diver in a team can call the dive with it, and the correct response is to acknowledge and go up together, without negotiating.
How do you signal that you are out of air?
A flat hand drawn across the throat, usually followed by pointing to your mouth or making the share air signal. It is one of the very few signals treated as an emergency on sight. The receiving diver presents their alternate air source immediately rather than asking questions, the pair establishes a firm hold on each other, and they begin a controlled ascent together without pausing to work out what happened.
Are scuba hand signals the same everywhere?
The core set is close to universal, and OK, up, down, stop, low on air and out of air are recognised worldwide. Beyond that they vary by agency, by region and by operator, and number signals above five vary a great deal. That is why the pre-dive briefing and the buddy check exist. Agree the signals you plan to use with the person you are actually diving with, before the dive.
What is the difference between low on air and out of air?
Low on air, a fist against the chest, means you have reached your planned reserve and the dive is turning now. It is a planning signal, not an emergency. Out of air, a hand across the throat, means you cannot breathe from your own supply and need a regulator from your buddy immediately. Confusing the two at distance is common, so make both signals large and deliberate.
How do you communicate something with no signal for it?
Write it down. A wrist slate settles anything the standard set cannot express, which includes headings, pressures, names of things and any question with more than a yes or no answer. Trying to mime a complex message underwater wastes gas, causes misunderstanding, and often ends with both divers agreeing to something neither intended. A pencil removes all of that in about ten seconds.
How do you get a buddy attention underwater?
Voice through a regulator carries poorly, so use a sound or a light. A tank banger or two taps of a hard object on the cylinder works at short range, and at night the standard method is to sweep your dive light across your buddy field of view, never directly into their eyes. If neither works and they are close, a firm touch on a fin or a forearm is normal and expected.
How we choose: we compare published manufacturer specifications, published training agency standards, and verified owner reviews across retailers. We do not test gear in person, and every depth rating, cylinder capacity and algorithm name quoted here is the manufacturer's published figure unless we say otherwise, so confirm it on the current spec sheet before you buy. Nothing here is dive instruction, and no calculator output on this site is a dive plan. Scuba diving carries a real risk of decompression sickness, oxygen toxicity, barotrauma and drowning. Dive within the limits of your certification, verify every plan with your own computer, and buy the training before the gear that assumes it.
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