Scuba Diving Hand Signals Every Diver Must Know

Forty feet underwater, surrounded by nothing but the sound of your own breathing, and your buddy is trying to tell you something. You can't hear them, you can't read their lips, and your dive slate is clipped to the back of your BCD. Your hands are your only voice underwater. Knowing your hand signals isn't just part of your certification. It's a skill that could one day save your life or your buddy's.

Why Hand Signals Matter More Than You Think

There are over 200 recognised hand signals used by divers worldwide. Most recreational divers only need to master around 15–20 of them fluently. But those 15 signals cover every situation you'll encounter on a normal dive, from checking in with your buddy to declaring an out-of-air emergency. Misreading a signal underwater can delay a critical response. Practise them until they're automatic.

The Golden Rule: Thumbs Up ≠ OK

This is the number one mistake new divers make. In everyday life, a thumbs up means "great." In scuba diving, thumbs up means one thing only: ascend now, the dive is over. If you're OK underwater, use the OK signal. Never thumbs up, unless you want to end the dive.

Essential Safety Signals

OK ✅

Underwater: Touch your thumb to your index finger to form an "O", extend the other three fingers upward.
On the surface: Raise one arm overhead and touch your fingertips to the top of your head, forming a circle with your whole arm.
This is both a question and an answer, use it to ask "Are you OK?" and to reply "Yes, all good."

Not OK / Problem ⚠️

Hold your hand flat, palm down, and rock it side to side like a wobbling fish. Then point to the source of the problem : your ear, your equipment, your chest. This signal means "something is wrong" and always requires a response from your buddy.

Ascend / Go Up 👍

Closed fist, thumb pointing straight up. This is a direct instruction: we are going up, now. When any diver in a group signals thumbs up, the entire team ascends, no exceptions.

Descend / Go Down 👎

Closed fist, thumb pointing straight down. Given by the dive leader at the start of a dive, or to signal a descent to a specific depth.

Stop ✋

Open hand, palm flat facing your buddy, fingers together and pointing up. Hold your position, do not move. Used when a diver spots something that requires attention, or when spacing between divers needs to be corrected.

Come Here 👋

Extend your arm toward your buddy and curl your fingers toward you in a beckoning motion. Used when divers drift apart or when something needs immediate attention.

Air Management Signals

These signals are critical. Running low on air without communicating it is one of the most dangerous situations in recreational diving.

How Much Air? 💨

Tap your fist on your chest. This is a question: "Check your pressure gauge and tell me how much air you have." A good buddy checks proactively, don't wait to be asked.

Low on Air

Hold your fist against your chest and tap it several times. Means your tank is getting low, typically under 70 bar (1,000 psi). Time to begin moving toward the exit or boat.

Out of Air 🚨

Slice a flat hand horizontally across your throat in a cutting motion. This is an emergency signal, it means "I have no air, I need yours now." Every diver must know this signal and be ready to respond by offering their alternate air source (octopus) immediately.

Share Air / Buddy Breathe

Point two fingers at your eyes, then at your buddy's regulator, then at your own mouth. This signals a request to share air from their alternate second stage.

Navigation & Dive Management Signals

Turn Around / Go Back

Extend your index finger and rotate it in a circular motion, then point in the direction of the exit. Used when it's time to reverse course and head back.

Level Off / Stay at This Depth

Hold your hand flat, palm down, and move it horizontally side to side, like smoothing a table. Signals to maintain current depth.

Slow Down

Hold both hands out flat, palms down, and push them gently downward. Used when a diver is moving too fast and burning through air unnecessarily.

Look / Watch This

Point two fingers at your own eyes (like "watch me"), then point with an open hand toward what you want your buddy to see. Always use an open hand to point direction, a closed fist pointing has a different meaning.

Marine Life Signals

These aren't safety-critical but they make dives infinitely more fun:

• Shark: Place one hand flat on top of your head like a dorsal fin
• Turtle: Cross your thumbs and flutter both hands like flapping flippers
• Manta Ray: Extend both arms out wide and flap them slowly up and down
• Octopus: Hold both hands in front of you and wiggle all eight fingers
• Moray Eel: Hold one arm straight out and open and close your hand like a biting mouth

Quick Reference: The 10 You Must Know Cold

Signal Gesture Meaning OKThumb + index finger circleAll good / Are you OK? Not OKFlat hand rocking side to sideSomething is wrong AscendThumb upGo up / End dive DescendThumb downGo deeper StopOpen palm facing buddyHold position Air checkFist tapped on chestHow much air? Low on airFist tapped repeatedly on chestRunning low Out of airHand slicing across throatEmergency : need air now Turn aroundRotating index fingerReverse direction LookTwo fingers at eyes, open hand pointsLook at this

Tips for Communicating Underwater

• Make eye contact first before signalling, a signal your buddy doesn't see is useless
• Signal slowly and deliberately, rushed gestures are easy to misread
• Always wait for acknowledgement, your buddy must signal back to confirm they understood
• Practise on land before every dive, especially with a new buddy
• Carry a slate for anything beyond the standard signals, a $5 wrist slate handles any situation

Final Thoughts

Hand signals are the universal language of diving. They cross every nationality, every certification agency, every language barrier. Learn them once, practise them often, and they'll become second nature within a dozen dives. Your buddy is counting on you and you're counting on them.

New to the sport? Check out our Complete Scuba Gear Checklist for Beginners and learn how to equalize your ears properly on descent before your next dive.