VIDEO: Shirtless Zac Efron Swims Behind the Scenes!

Finally! A Zac Efron interview where he is shirtless! The Charlie St. Cloud star takes you behind his underwater scene!

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In a new Charlie St. Cloud featurette, Zac shoot scenes underwater.

“It takes up pretty much the whole stage,” Zac said of the huge tank. “Underwater, there’s this system… but you can actually hear voices underwater! I have no idea how it works."

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“It’s a lot of stuff you wouldn’t have to expect you have to deal with,” Zac added. “When there’s elements involved like swimming through murky water, getting a certain piece of your vest snagged, very precise movements…it’s hard to hold your breath!”

Watch the clip below!