NO PERSON could keep that shark from killing them. Not even with any gun.
The ocean is totally their territory, we're intruding everytime we go in. I don't let it bother me though. Where I go to the beach, there's never really been a shark attack that I've heard of.
Although last year, me and my friend were way out, just swimming, and a baby shark (I'm pretty sure it was a fucking shark) about 2-3 ft. long jumped like 6 ft. out of the water, about 15 or 20 ft. in front of us. We just halued ass back. We were out like 8 ft. deep.
It's fun though. Good stories like that one.