More than 375 species of sharks swim the world's oceans, but you'll probably only see a fraction of those in your diving experiences. Your shark encounters will be limited by where you're diving, as different species of sharks, much like bears or snakes, are comfortable in some ocean areas and not in others. Where they are found largely depends on the same things that keep brown bears out of the Great Plains: climate and availability of food. Companies will know exactly where to go to find the most sharks.
Perhaps you are eager to see a great white shark. As a result of this intimidating animal's fame, entire companies devote their time to taking people out to see the great white in action. That being said, there are numerous sharks that you might see on a dive, and all of them hold the same power and excitement. Some common species that might swim by include blacktip reef sharks (which look very similar to the great white except for a black mark on the dorsal fin), tiger and bull sharks, and the very distinctive hammerhead shark.
It's worth repeating that no matter the species, these are all predators, and swimming with them poses as much risk as any outing involving wild animals. Most sharks, though, are only curious about divers and will leave them alone unless they feel threatened or are agitated to the point of attack. Of the 375 species worldwide, only about 30 have been identified as attacking a human, and only a dozen or so of those should be considered dangerous. The species that have been most associated with unprovoked attacks are great white, tiger and bull sharks [source: National Shark Research Consortium, Shark Attacks].
All this begs the question, what is the actual risk of a shark attack, and how should you handle an attack if it happens? Read on to find out.