Eight sharks! And not just any sharks -- when I climb back on the boat in a half hour or so, the dive master will tell me that those were Bull Sharks, the most dangerous shark in the ocean. But right now, I'm about 75 feet underwater with my wife and daughter, here, hanging on a rock, entranced by eight beautiful, circling Sharks. Later, though, when I tell people what I did for summer vacation, most of those people think I'm nuts.
The thing is, shark diving is really pretty safe. Here's why I think so...
Many people, when you ask them why they think sharks are dangerous, will tell you to look at the statistics. I think that's a pretty good idea. The University of Florida keeps tabs on shark attacks at the International Shark Attack File. Check them out at:http://www.flmnh.ufl.edu/fish/Sharks/ISAF/ISAF.htm
They'll tell you that "Worldwide there are probably 70-100 shark attacks annually resulting in about 5-15 deaths." PADI, alone, certifies more than one million divers a year -- assiming about 10% are of those attacks are versus divers (the shark attack file provides this percentage), that those are the only divers in the ocean (this assumes that people quit diving after they get open water certified), that's about 1/1000 of 1% chance of getting attacked EVER (not killed, just attacked). Now, looking at fatalities, the number of deaths by shark attack worldwide in 2005 was...four. In 1987 (the last year for which I can find data), more than five times as many people got bitten by squirrels in New York City than were bitten by sharks in the whole United States (though, I must admit, people usually don't lose a limb even to the nastiest squirrel).
You'll find that the number of unprovoked fatal shark attacks is EXTREMELY low (IIRC, you're more likely to be trampled to death by elephants than killed by a shark). Also, the scuba bubbles scare sharks (and many other marine animals). Most of the sharks you see will be from the rear -- as they're swimming away from you.
Some more information: sharks are lazy (as top-tier predators, they have to be or they expend too much energy getting food than they get from the food). Lazy predators don't want a fight -- they want a quick and easy meal. Unless a shark is 1.5 to 2x your size, you're going to be a fight and not worth going after. You are a lot less likely to find those than the small ones. Even then, many large sharks aren't anything to be worried about.
There's more information but that should go a long way to putting your mind at rest.
FWIW, I really enjoy diving with sharks; I go out of my way to do that. It takes a lot of work for us to find sharks and dive with them.