Think of the worst band on Earth. Yanni. The Yodel Sisters. No, wait — Alvin and the Chipmunks. Picture them live and cranked it to 11. Now imagine having hundreds of ears. How close could you get to the speakers before it became physically unbearable? That's the idea behind Shark Shield's technology. Except instead of volume, they use voltage.

Ever seen a shark's snout up close? It's covered with clogged pores — almost like acne — called the "Ampullae of Lorenzini." (The average hammerhead has more than 3000.) Each one marks a channel from 3 to 20 centimeters deep, filled with gel and sensory hair cells for detecting and processing the tiny electrical charges that all animals produce — making predatory sharks the most electro-sensitive animals in the world. In 1998, South Africa's Natal Shark Board discovered you could "jam" these sensors. Ten years later, Shark Shield created a portable device that mounts to a scuba diver's calf or a surfer's board and trails a three-meter cord slightly thicker than a legrope. It only emits a small, 12-volt pulse every half-second but — since sharks can detect signals as weak as one-half billionth of a volt — the effect is like hooking the fish with a taser, sending muscle spasms though its body until it retreats.

"They physically quake," says the company's Chris Bosley. "We've had scuba divers report seeing a big white come right at them, boomerang backward at about the four-meter mark, then circle around them at that exact distance."

The result is a protective radius between three and five meters. But, don't worry: it doesn't cause any permanent damage; and it doesn't affect other sea life — except stingrays. Better yet, the bigger the shark, the more Ampullae in its snout, the more sensitive it is, the greater the electric field. And there's a more powerful model, the {{{Mariner}}}, that triples the output to 15 meters, built for attaching to buoys off lineups as "safety points" for surfers to paddle to in case of a sighting —almost like "anti-chum." Wait, make that exactly like anti-chum.

"{{{Commercial}}} fishermen have begun hanging them off boats for when they pull in a catch," Bosley continues. "That's when the fish are weakest and most prone to attack, but sharks still can't get through. It's like a force field. No matter how bloody the water, they'll turn themselves inside out to get away."

And you thought you hated Hanson.