The Marvel star joins Grylls in the season 6 premiere of his National Geographic series, airing Monday night, and is subjected to the usual rigorous survival challenges, including rappelling down a massive cliff. As Grylls notes in the exclusive clip above, "I do a lot of climbing and rappelling, but this drop even makes me nervous. The rocks are unstable, the cold is numbing our hands, and it's a dizzying height to the bottom."
"This is why I have stuntmen," Mackie quips, adding, "I'm going full Tom Cruise." (Speaking of which... he'd be a great Running Wild guest!)
The Falcon and the Winter Soldier actor is the latest celebrity to take part in the punishing reality series, whose previous highlights include Nick Jonas crossing a frozen lake in his underwear, Michelle Rodriguez eating a urine-soaked mouse, and President Obama consuming a half-eaten fish. Ah, wilderness.
Running Wild (which previously aired on NBC) is part of Nat Geo's new Adventure Night programming, which also includes the series premiere of the new competition show Race to the Center of the Earth. That series pits four teams against each other in a race for a $1 million prize, with each group starting on a different continent.
Season 6 of Running Wild With Bear Grylls premieres on Nat Geo at 9 p.m. ET on Monday, followed by Race to the Center of the Earth at 10 p.m.