Another manufacturer:



From Mythbusters:
Magnets are effective for repelling sharks.

busted

"This myth is based on the fact that sharks have sensory organs called ampullae of Lorenzini, which are capable of detecting electro-magnetic fields. The Mythbusters tried several experiments to test the deterrent power of magnets. First they used a young, captive nurse shark. A handler immobilized the shark by turning it upside down. Jamie then brought a magnet near the shark, and it bent away from the magnet. When the shark was upright, it bent away strongly and tried to escape from the handler. The Mythbusters also used a sheet of plastic to hide the approaching magnet from the shark’s vision. In this condition, the shark tried to bite at the magnet through the opaque sheet when the magnet was brought near. Next, another nurse shark was used for a different test. The shark was in a small pen, and the a row of magnets was used to divide the pen in half. The shark would not swim over the magnets, but it would swim over a line of steel chunks used as a control. Finally, the Mythbusters covered fish-filled bait boxes with strong neodymium magnets and submerged them in waters infested with wild, adult lemon sharks. These sharks attacked the boxes aggressively regardless of whether there were magnets on them. This myth was declared “busted” because the magnets did not work for all species of sharks nor when there was food present."

Some various posts around the Internet on magnets as shark repellents:

Hooray for the news media giving free advertising to fraudsters.
It might actually work if you use big-ass rare earth magnets or an electromagnet so the shark could detect it more than six inches away, but those same magnets would make it quite tricky to stay on the surface for very long.
I'm guessing the feet that washed up BC were from the beta testers then?
Fortunately the bracelet is effective at repelling Nurse Sharks.Unfortunately the bracelet is effective at attracting Great White Sharks.
It’s only a matter of time before the product is recalled and they’re being sued by a bunch of angry (not to mention limbless) customers…
okay let’s just say this works and the sharks are repelled..the shiny glistening beading will surely attract barracuda…still want that cool embellishment?
At Least My Ankles Will Be Spared! Should have worn it on my friggin wrist!
Here is a rather well done article with citations:

http://animals.howstuffworks.com/fis....htm/printable



I think Batman's shark repellent spray might work better.