Swim with the Sharks Off Isla Mujeres

Mexico's Isla Mujeres -- off the Caribbean coast near Cancun -- is one of the best places to swim with sharks, USA Today reports. It's also a heck of a lot easier to get to than some of the other places on the list (like the Great Barrier Reef and Palau), and because they're plankton-loving whale sharks, the Isla Mujeres population will consider you "friends, not food." Which is good, because whale sharks can be up to 50 feet in length, weigh up to 10 tons, and can travel in packs of up to 50.

A number of Isla Mujeres outfitters organize whale-shark tours, including Ceviche Tours, Searious Diving, and Aqua Adventures. Isla Mujeres also holds an annual Whale Shark Festival every July.