Underwater, you can’t exactly lean over and say “hey, I’m getting low on air, let’s head back.” So divers talk with their hands. Hand signals are the language of the sport, and knowing them cold — and agreeing them with your buddy before you drop — is a genuine safety skill, not just a nice-to-have.
Here’s a run-through of the essential scuba hand signals every diver should know, plus how to use them so your message actually gets across.
The one everyone gets wrong: ‘OK’
Start here, because it trips up beginners. The “OK” signal is thumb and forefinger together in a circle, other fingers up. It’s both a question and an answer — you signal it to ask “are you okay?” and your buddy signals it back to say “yes, I’m okay.” What it does not mean is “go up”; that’s the thumb. And a thumbs-up does not mean “great, all good” the way it does on land — underwater, thumb up means “let’s ascend.” Getting those two straight is lesson one.
At the surface, where you might be too far to make the small hand signal clearly, “OK” can also be a hand on top of the head (arm in a big loop) or both arms in a circle overhead — the big versions carry at a distance.
The core signals
These are the ones you’ll use constantly. Commit them to memory.
Up — thumb pointing up: let’s ascend / end the dive. Down — thumb pointing down: let’s descend. Stop — a flat, open palm held up, like a traffic cop. Something’s wrong / not okay — a flat hand rocked side to side, often followed by pointing at the problem (your ear, your head, whatever it is). Level off / stay at this depth — a flat hand held palm-down, patting the water.
Low on air — a closed fist to the chest (or the specifics you’ve agreed): I’m getting low, let’s think about heading back. Out of air — a flat hand slicing across the throat: this is an emergency, I need to share air now. These two are the most important signals you’ll ever give, so make sure you and your buddy both know them without hesitation.
Which way / direction — a flat hand or point indicating where you’re headed. Look / watch — two fingers pointing from your eyes to whatever you want them to see (this is how you share the cool stuff). Come here / stay together — a beckoning hand. Buddy up — two fingers held together.
Numbers and details
You’ll also want to communicate numbers — your remaining air pressure, mostly. Divers use finger counts, and there are conventions for the larger numbers, but the specifics are exactly the kind of thing to confirm with your buddy on the surface rather than assume. That’s the theme here: agree your signals before the dive.
Agree them before you descend
Here’s the part people skip. Hand signals aren’t perfectly universal — there’s regional variation, agency variation, and personal habit. The fix is simple and takes thirty seconds: as part of your pre-dive plan, run through the key signals with your buddy so you’re both on the same page, especially anything non-standard you like to use. A signal only works if the person watching reads it the way you meant it.
Signalling so you’re actually understood
Two practical habits. First, get your buddy’s attention before you signal — a signal nobody’s looking at communicates nothing. A wave in their field of view, a tank tap they can hear, or a light beam swept across their line of sight (never in their eyes) all work. Second, make your signals deliberate and clear rather than a vague flap. Underwater, an ambiguous signal can be worse than none, because it invites a wrong guess. Slow, clear, confirmed.
Learn them properly
Hand signals are taught from your very first course, and they become second nature with practice — but they’re worth a deliberate refresher if they’ve gone fuzzy. They’re core to the way we teach and dive, and if you’re just getting certified you’ll build them in from day one. Got a question about a specific signal or convention? Our FAQ is a good starting point, or just ask us.
Learn the language, agree it with your buddy, and the whole dive gets safer and more fun — because now you can actually share it.
