Even the best-rigged dive boat can't help you if you lose your way underwater or are swept away by current. When the unthinkable happens and you surface to an empty blue ocean, you need emergency signaling gear. To be seen and heard, the pros from ScubaLab's test team (scubadiving.com) at Boating's sister magazine recommend carrying both visual and audible devices.
Nautilus Marine Rescue GPS
ScubaLab's Testers' Choice winner, this waterproof NautilusGPS broadcasts a digital man-overboard signal with GPS coordinates to any boat within 34 miles equipped with an AIS-enabled VHF radio. Open the cap, press the blue button, pop off the retainer to unfurl the 9-inch antenna, and hold the red button for five seconds. $199; nautiluslifeline.com
DAN Signaling Sausage
Bright orange and nearly 8 inches wide, this tube was visible in the daytime from a half-mile away in our test, thanks to a 2-inch-wide vertical reflective strip that flashes in the sun. It has a mesh pouch that can hold emergency supplies, like a light and mirror. $80; dan.org/store
Tektite Strobe 3500
This emergency strobe has full 360-degree coverage, so you don't have to aim it to be spotted. During our test, the strobe was clearly visible a mile away and became brighter as the sun set. Tektite says the three C batteries burn for 100 hours on flash; ours was still going like new after 70 hours. $89.95; tek-tite.com
Dive Alert Plus V.2 Air Horn
Its foghornish honk is clearly audible from a mile away, is easy to install, and clips in between your hose and power inflater. Trust us, it's ear-splittingly loud. $89.95; divealert.com
Trident Fold-Up Divers Alert Flag
This collapsible flag can easily be stowed in a buoyancy-compensator pocket or attached to a D-ring, so it's out of the way when it's not needed. $25.95; leisurepro.com
