The best option is to avoid them altogether by staying out of the water during warnings or by making sure not to swim near seals -- one of their favorite snacks. Keep away from fishing boats and fishermen as well.
But if you ever do find yourself in an encounter, here are some things you can do, according to an article on CNN Travel:
- Punch it in the nose. Yep, the nose is a sensitive area, as are the gills.
- Be active, not passive. Playing dead only tells the shark it won, at which point it'll chow down.
- Avoid splashing around. Yes -- this sounds ridiculous. But the more you splash, the more it excites the shark. If a shark is circling, back away slowly.
- Look it in the eye. Sharks like an ambush, and you can help discourage it from attacking by continuing to face it as you swim away slowly.