Using Emergency Signaling Devices on the Surface
Learn how to choose and use emergency signaling devices on the surface so you can get attention fast and stay safe after a dive.
SAFETY WHILE DIVING
Using Emergency Signaling Devices on the Surface
Even the best-planned dives can end with a little more distance between you and the boat than you expected. Strong currents, choppy waves, or simply surfacing away from the planned spot can make it hard for a crew to spot you. That’s where emergency signaling devices come in—they bridge the gap between “I’m fine, but you can’t see me” and “Hey, over here!”
There are two main categories: visual and audible. Visual devices are designed to catch the eye, whether it’s a bright surface marker buoy (SMB) standing tall above the waves or a small signal mirror flashing in the sun. An SMB is a must-have for open water, especially in areas with boat traffic. Inflating it before you surface gives anyone nearby a clear target to keep an eye on. Mirrors may seem old-fashioned, but they’re surprisingly effective on sunny days and weigh next to nothing in your kit.
Audible devices—like whistles or air horns that attach to your low-pressure inflator hose—are great for grabbing attention when visibility is poor or the wind is loud. A whistle works well in calm conditions, while an air horn can cut through the roar of an engine or crashing surf.
The real trick is knowing when and how to use these tools. If you’re drifting away from the boat, deploy your SMB early so it’s already visible when you surface. If you spot the crew but they’re not looking your way, a few sharp blasts from a whistle or air horn can quickly turn heads.
It’s also worth practicing with your devices before you need them. The middle of a current-swept channel is not the place to figure out how to inflate a delayed SMB or aim a mirror. A little rehearsal means faster, calmer action when it matters.
In diving, being prepared isn’t just about the time underwater—it’s about making sure you’re safe from start to finish. Emergency signaling devices are small, lightweight, and easy to pack, but when you need them, they can be the most important pieces of gear you own.
Common Surface Signaling Options
Surface Marker Buoy (SMB) or Delayed SMB (DSMB) – Bright, inflatable tubes that make you visible to boats and your dive crew.
Whistle – A compact, high-pitched sound signaler that works well in windy or noisy surface conditions.
Dive Alert (Air Horn) – Connects to your BCD inflator hose and uses tank air for a loud, attention-grabbing blast.
Signal Mirror – Reflects sunlight to catch the eye of a boat or helicopter at a distance.
Waterproof Strobe or Torch – Especially useful in low light or at night for drawing attention.
Fluorescent/High-Visibility Flag or Cloth – Can be waved to signal location in calm surface conditions.
Choose the signaling device that best fits your diving environment, typical visibility conditions, and personal comfort level — you don’t need them all, but having at least one reliable option can make a big difference in an emergency.
Happy and safe diving,
The ScubaBlast Team
Divers Alert Network. (n.d.). Signaling devices for divers. Retrieved from https://dan.org/health-medicine/health-resources/dive-safety/signaling-devices-for-divers
PADI. (n.d.). Surface marker buoys: The diver’s flag in the water. Retrieved from https://www.padi.com/articles/surface-marker-buoys