Zac Efron was one of Bear's guests on his show "Running Wild" - and they decided to repel off this cliff!! I mean - really the best part is just that Zac takes his shirt off - HAHA!! JK - It's exciting to see them go repelling ;) 

Check out the instagram video below of Zac going skydiving!! 

Video Credit - Instagram @ZacEfron

"From his first skydive to #RunningWild with @BearGrylls, #ZacEfron is kicking off the #RunningWild season with a bang July 28th at 8/7c on NBC and will be live tweeting his episode! Follow on Twitter at http://twitter.com/ZacEfron to watch with Zac and get the inside scoop before you see the show at http://bit.ly/zerwbear!"