We already knew that Tom Cruise is a wild man who insists on doing his own stunts in movie after movie, but he just keeps proving to us just how far he’s willing to go. For this year’s Mission: Impossible - Rogue Nation, Cruise now-famously strapped himself to the side of an airplane and flew around several times to nail a key moment in the film’s opening scene. The plane stunt might be among the most daring things Cruise has ever done, but it wasn’t the only extreme thing he did to capture a Rogue Nation moment.

In a new featurette from the film, Cruise and crew reveal that, for the sequence in which Ethan Hunt must infiltrate a databank kept in a secure and very deep tank of water, the star actually learned how to hold his breath for up to six minutes.

“Normally in underwater sequences, people hold their breath for 10 seconds, 15 seconds max,” Cruise said. “So I had to prove to everyone that it was actually safe, and spend time with the safety guys and the safety officers to show them, look, not only is it safe, it’s better that I know how to hold my breath because I’m going to be very relaxed. No one’s going to have to rush in, no one’s going to have to panic.”

To perfect the breathing techniques needed for the movie, Cruise and his co-star Rebecca Ferguson underwent a military training program specifically designed for long breath holds, and just in case you think he’s making it up, there’s a time lapse video with a timer to prove that, yes, he really is holding his breath that long.

Check out the video:

Tom Cruise’s Underwater ‘Mission: Impossible’ Training (Exclusive)