One of the most profound things about scuba diving is the absolute silence. The moment you slip beneath the surface, the noise of the boat engines, ringing phones, and everyday life completely vanishes. But losing your ability to speak comes with a massive challenge: how on earth do you tell your dive buddy that there is a massive sea turtle right behind them?

If you don’t know your standard hand signals, diving quickly devolves into a game of aggressive underwater charades. While it’s funny to watch someone try to mime a moray eel, poor communication can turn a minor problem into a major panic.

Whether you are a newly certified Open Water diver or you are gearing up for a shop trip to Fiji, here is a refresher on the universal language of diving that you need to have hardwired into your brain.

The Non-Negotiables: Safety and Air

These are the signals that keep you alive. They should be sharp, clear, and immediately acknowledged by your buddy.

• “Are you OK?” / “I am OK!”: Form a circle with your thumb and index finger, extending the other three fingers. This is a question and an answer. If your buddy flashes this to you, you must reply with the same signal to confirm. Do not give a thumbs-up (we will explain why in a second).
• “Low on Air”: Bring a closed fist to your chest. This doesn’t mean you are out of air, but it tells your buddy and the divemaster that it is time to start navigating back toward the boat or shore.
• “Out of Air”: A flat hand slicing across your throat. This is an immediate emergency. Your buddy should immediately swim to you and deploy their alternate air source.
• “Up” (End the Dive): A closed fist with the thumb pointing straight up. This is the most misunderstood signal by new divers! In the real world, a thumbs-up means “Awesome!” Underwater, a thumbs-up means “I am ascending to the surface.” Never use a thumb to say you are having a good time.
• “Down” (Descend): A closed fist with the thumb pointing straight down. Used at the beginning of the dive to signal it is time to drop below the surface.

The Problem Solvers

Things don’t always go perfectly perfectly smoothly. When a minor issue pops up, you need to communicate it before it becomes a major one.

• “Something is wrong”: Hold your hand out flat, palm down, and wobble it side to side (like the “so-so” gesture). You immediately follow this by pointing to the source of the problem with your index finger.
• “Ear Problems”: Wobble your hand (“Something is wrong”), then point directly to your ear. This tells your buddy to stop descending while you try a different equalization technique.
• “I am cold”: Cross your arms over your chest and rub your upper arms. If a diver is shivering, they are burning through their air rapidly. It might be time to move to shallower, warmer water or call the dive.
• “Stop” or “Hold”: A flat hand held up, palm facing your buddy (like a traffic cop). Alternatively, a closed fist held up at shoulder height. This means stop swimming and hold your position.

The Fun Stuff: Marine Life Signals

Once the safety checks are done, it is time to look at the reef! Dive guides use a whole vocabulary of animal signals to point out camouflaged critters before they swim away.

• Shark: Place a flat hand vertically against your forehead, like a dorsal fin.
• Sea Turtle: Stack your hands flat on top of each other, palms down, and twiddle your thumbs in circles like flipping flippers.
• Ray: Place your hands flat next to each other and slowly flap them up and down like wings.
• Nudibranch (Sea Slug): Hold up two fingers (index and middle) on one hand and wiggle them like tiny antennae.
• Moray Eel: Use one hand to form a mouth (thumb on the bottom, four fingers on top) and open and close it rapidly.

The Pre-Dive Huddle

Here is the golden rule of dive communication: Always review your signals before you get in the water.

If you are traveling and get paired up with an “instabuddy” from a different part of the world, their signals might be slightly different. For example, some divers signal a half-tank (usually 1500 psi or 100 bar) by holding their hands in a “T” timeout shape, while others hold a single fist up in the air. Take two minutes on the dive deck to review the basics: “How do you signal half tank? How do you signal turn around?”

Communication is the foundation of the buddy system. Master these signals, and you will never have to play underwater charades again!