As regular viewers of a certain TV channel will already know, the orca (or killer whale) is one of the only animals that kills sharks. It would follow, therefore, that sharks generally try to stay away from them. It was with this fact in mind that the SharkStopper Personal Shark Repellent (PSR) device was created. The ankle-worn gadget emulates orca vocalizations, and has reportedly been shown to repel various species of sharks.
Read the full article: SharkStopper is claimed to make you sound scary to sharks