I've heard the theory that getting bitten by a shark in on the same order of risk as being hit by lightning. I disagree with that. You can't avoid lightning, but if you don't go in the ocean, you won't get bitten by a shark.
The only thing that ever bit me in the water at the beach was a crab. I kicked my leg out of the water and the little bugger went flying. (Jellyfish don't bite, but I've been stung plenty of times.)