In the first clip for survivalist Bear Gryll's "Running Wild," a new series where he takes celebrities on weekend adventures, we see him and Zac Efron rappel shirtless next to a waterfall. Yes, these guys are both jacked and yes, network execs are extremely happy that Bear Grylls told Efron to take his shirt off for the stunt. 

"We reached out to [Efron] and he kindly said he was a fan of the show and that he was in 120 percent," Grylls said. "He asked for the biggest, baddest adventure and it was an honor to oblige.

"I like to think he got to use his muscles to their max through the adventure," he added to People

In addition to the waterfall stunt, Efron also jumped out of an airplane with Grylls. The 26-year-old is one of many celebs taking part in the series - including Channing Tatum, Ben Stiller, former NFL pro Deion Sanders, “Today” anchor Tamron Hall and Tom Arnold. 

"‘Running Wild' allows viewers to see inside the hearts and minds of these guests in a very open, honest and vulnerable way, pushing them out of their comfort zones and seeing what they are like in real life when stripped of all the benefits of celebrity," Grylls said in a statement. "Ultimately, this show is about taking these stars on the adventure of a lifetime and being alongside them when they discover something new and empowering about themselves and their world. For me, that is always a privilege."

Check out the videos below. "Running Wild" premieres July 28th. 

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Bear Grylls and Zac Efron rappel off a cliff in first 'Running Wild' clip
And yes, they're both shirtless.