Mark Zuckerberg Surfing with Ankle Bracelet That Drives Sharks Away

Mark Zuckerberg not taking any chances sharing the ocean with sharks ... because he's hooked himself up to a contraption that supposedly keeps them at bay.

Mark was out on his hydrofoil surfboard in Kauai, Hawaii Thursday, wearing an ankle bracelet called Sharkbanz. The promise is that sharks don't like what it emits, so they stay clear of surfers. The device sends out an electrical current that apparently drives sharks away.

But, there are other, more subtle deterrents. His board has a zebra pattern underneath ... the theory goes that sharks like seeing solid colors because it resembles food, so they're not into stripes. Good theory, but sounds a little sketchy.

Shark Week is coming up on Discovery ... they shoulda featured Mark on how not to get eaten!

Zuck posted video of him on the board, and gotta say .... he's really good in the water. It's pretty choppy, but Mark stays up and bounces atop the swells. He's been surfing for years.