Didson Diver-Held Sonar
Sometimes venturing underwater isn't about taking stunning pictures of marine life or discovering a new species. Sometimes you dive in because you have to find a critical bit of evidence that's been lost, or tossed, in the sea – like, say, guns, boats, or bodies.
And sometimes you have to look for such things in water about as clear as a milkshake. Mike Zinszer knows this as well as anyone. He's a former Navy diver and professor at Florida State University, where he's the director of advanced science diving at the Panama City campus and runs the Underwater Crime Scene Investigation Program. Which is why Zinszer's aquatic world lit up when the Didson Diver-Held sonar recently came along. Think night-vision goggles for divers.
"It's literally like you're giving sight to the blind underwater," Zinszer says.
Using conventional sonar at the surface provides only an approximate location. In murky water, it can be difficult – and time-consuming – to pinpoint an object, whether you're looking for a .357 Magnum or a jet engine.
Sound Metrics Corp., conceived a decade ago in the Applied Physics Lab at the University of Washington, developed imaging sonar that transmits sound pulses and converts the returning echoes into digital images, sort of like a medical ultrasound sonogram. With the Didson Handheld, a viewfinder attaches to a diver's mask and the invisible becomes visible – and recordable.
"This technology is a good tool to search in small areas," Zinszer says, "it's not like scientific scanners that cover a large area. You can pick out a pistol in zero visibility."
Diver-held sonar is available to anyone bent on exploring muddy waters. A Didson unit goes for $74,000 and up at serious ocean outfitters like Ocean Marine Industries in Chesapeake, Virginia. It's a lot of money, but there is no cheaper way to explore in dark water – unless you count feeling around with your hands for months at a time.