Well, I saw Phunkie's thread linked in the Anniversary thread, and decided that instead of bumping a long since dead thread, I may as well make a new one.
I don't want to necro the thread, but they have "armors" you can wear if you're really concerned: http://www.neptunic.com/
Though, they're quite expensive... They also have these ankle things that give off a current or something that sharks hate.
There's also a shark shield - check out the vid:
[video=youtube;iZ_8dLnN8aE]http://www.youtube.com/watch?v=iZ_8dLnN8aE[/video]
There's specific shark shield surf boards made too...
[video=youtube;XjtAwlvgNpQ]http://www.youtube.com/watch?v=XjtAwlvgNpQ[/video]
Here's someone attacked that lived because their friend had it:
[video=youtube;qVsp12iYSUc]http://www.youtube.com/watch?v=qVsp12iYSUc[/video]