although I think it was a repeat, on mythbusters they did the whole show on some of the myths of sharks. Very cool, they did show that it was "plausable" to drive a shark away from you, albeit momentarily, by whacking it in the nose.
Could give you enough time to get out of the water or find shelter.
Gambitt, i hope you were watching this one. :D
Also showed scenes of them diving the Bahama's with Stuart Coves undersea adventures.