The Facebook CEO was hydrofoiling, which is a new type of watersport that has grown in popularity among outdoor enthusiasts — and those with plenty of cash to spend on a piece of sporting equipment that costs thousands of dollars.

Though Zuckerberg is mostly known for being the awkward founder of the world’s largest social network and one of richest people on the planet, he’s also become one of the most visible hydrofoilers out there, bringing more attention to the up-and-coming sport.

While surfing requires the power of a wave to get going, and wakeboarding relies on a boat to tow the rider, hydrofoiling uses a winglike structure under the surface of the water to create lift. The rider uses a handheld bluetooth controller that connects to an electric motor and underwater propeller, or creates momentum manually by pumping their legs up and down, as Zuckerberg does in his Fourth of July post.

“It’s a hydrofoil. There’s a wing under the water that I’m riding that pushes the board into the air,” Zuckerberg wrote in a comment on his post. “It’s a lot of fun. There’s an electric-powered version that you can get, but in this video I’m riding a regular foil board and surfing a little wave.”

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