Look Out Below! Diver Has Incredible Encounter With Massive Whale Shark

Is this a near-fatal encounter with a ferocious shark?

Probably not. The beast in this one-of-a-kind shot is actually a whale shark -- the world's largest known extant fish species. Marine biologist Simon Pierce captured this amazing shot while diving off Isla Mujeres near Cancún, Mexico.

Despite their enormous size, whale sharks are actually filter feeders -- they suck in lots of water and feed mostly on plankton. They're often docile and generally don't pose a danger to humans.

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The relative ease of swimming with whale sharks has brought a rise in eco-tourism where the vulnerable sharks still remain, worrying some scientists and environmentalists.

Eco-tourism is generally viewed positively, the Washington Post reported in 2012, but as with other things, it must be managed properly.