Underwater, divers cannot speak. Hand signals are the primary means of communication between dive buddies, and knowing them fluently is both a safety requirement and a marker of diving experience. Some signals are universal across all dive training agencies; others vary by region, instructor, or dive operation. When diving with a new buddy or in a new location, always agree on signals before entering the water. Here is the complete set of essential scuba diving hand signals.
The Most Important Signal: OK
The OK signal is the most frequently used and most important to get right. It means “I am fine” or “Are you OK?” — and it is also the correct response when asked.
- Standard OK (surface): Form a circle with thumb and forefinger, three fingers extended — the universal “okay” gesture
- Underwater OK (alternative): Touch the top of your head with your whole hand (fingers together, palm down). This is preferred at distance because it is more visible than the finger circle.
- Surface OK (at distance): Hold one arm up in a circle above your head — used to signal “OK” to a boat or shore crew
Critical note: A thumbs-up underwater does NOT mean “OK” — it means “go up / ascend / end the dive.” Never confuse these.
Ascent and Descent
- Go up / Ascend: Thumbs up — fist with thumb pointing upward
- Go down / Descend: Thumbs down — fist with thumb pointing downward
- Level off / Stay at this depth: Hand flat, palm down, moved horizontally
Safety and Emergency Signals
- Problem / Something is wrong: Hand flat, palm down, rocked side to side (the “so-so” gesture)
- Out of air / Emergency: Hand cutting across the throat in a slashing motion — the universal distress signal. Requires immediate buddy air sharing.
- Low on air: Fist against the chest. Follow with the numerical amount of air remaining (shown in bar or PSI using fingers)
- Out of air — please share: Two fingers pointing toward your mouth (requesting the alternate air source)
- Emergency ascent: Fist to chest (out of air) combined with thumbs up (go up) — performed rapidly to communicate urgency
- I cannot equalize / ear problem: Point to ear, then give the “problem” hand signal
Navigation and Direction
- Come here / Follow me: Beckon with an index finger, or arm extended with hand waving toward yourself
- Go that way: Point with whole hand in the direction of travel
- Turn around / Go back: Index finger rotated in a circle, or arm swung in a 180-degree arc
- Stay together / Stay close: Two index fingers held together, side by side
- You lead / After you: Hand extended flat toward the other diver
Air and Diving Condition Signals
- How much air? Open hand placed on top of closed fist (miming a pressure gauge) — often followed by tapping your gauge
- Half tank / 50%: Flat hand, edge-on, perpendicular to the body (slicing gesture)
- Cold: Cross arms across chest and rub shoulders — the universal “I’m cold” gesture
- I don’t understand: Hand held flat in front of face and rocked side to side
Marine Life Signals
Many dive guides and buddies develop shorthand signals for common marine species. Some are widely standardized:
- Shark: One hand flat on top of the head, fingers pointing forward — mimicking a dorsal fin
- Manta ray / ray: Both arms extended to the sides, slowly flapping up and down
- Turtle: Both hands crossed at the wrists, thumbs interlocked, fingers spread like flippers — waved slowly
- Octopus: Both hands together, fingers spread and waving like tentacles
- Look / Did you see that?: Two fingers pointed at your own eyes, then pointed toward the subject
Skill and Communication Signals
- End the dive / Go up: Thumbs up (same as ascend signal)
- Safety stop: Three fingers held up — indicating 3 minutes at 5 meters
- Watch me / Pay attention: Point two fingers at your eyes, then direct toward yourself
- Take a photo of me: Frame a square with both thumbs and index fingers — the universal photo gesture
Numerical Signals (for air pressure)
Communicating remaining air in numbers:
- 1–5: Show that many fingers on one hand
- 6–9: Show the second digit on one hand while showing 1 finger of the other (indicating “tens” then “units”)
- 100 bar / 1500 PSI: Closed fist (representing 100 or 1500 depending on your system)
- 50 bar / 500 PSI: Five fingers on one hand (representing 5 x 10 bar, or 500 PSI)
Always establish with your buddy before the dive whether you are communicating in bar or PSI.
Key Facts
- Most important signal: OK — confirm understanding before every dive
- Most critical distinction: Thumbs UP = ascend (NOT “okay”)
- Emergency signal: Hand across throat = out of air
- Review before every dive: Signals with any new buddy or in any new region
Frequently Asked Questions
Are dive hand signals standardized globally?
Core safety signals (OK, ascend, out of air, problem) are recognized across all major training agencies (PADI, SSI, NAUI, BSAC). However, regional variations exist — particularly for marine life signals and air quantity communication. Always review signals with your buddy or dive guide before entering the water, even if you are both certified divers.
How do you signal an emergency underwater?
The hand-across-the-throat signal means “out of air” and requires immediate response — your buddy should offer their alternate air source (octopus regulator) immediately. The thumbs-up means “go up now.” Hitting your tank with your dive knife (if carried) produces noise that attracts attention. Banging your tank creates a sound audible across a surprising range underwater.
What happens if you panic underwater and cannot remember signals?
The universal behavioral indicator of a problem is erratic, rapid, or unusual movement. A diver waving their arms, swimming fast, or acting out of character is a signal that something is wrong — a good buddy watches their partner’s behavior as much as their explicit hand signals. In an emergency, make eye contact, point to yourself and then the surface, and ascend together.