It was one of the most exciting scenes in "Mission: Impossible - Rogue Nation." Tom Cruise stays underwater for minute after heart-pounding minute without using a scuba tank or surfacing to breathe.

The 53-year-old star insists this all happened without a stuntman or slick editing. Instead, he learned to hold his breath for more than six minutes.

"Normally in underwater sequences people hold their breath for 10 seconds, 15 seconds max, so I had to prove to everyone that it was actually safe," Cruise says in this behind-the-scenes video for Access Hollywood.

Cruise says he told the safety team on the movie: "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 has to rush in, no one has to panic."

Working with free-diving expert Kirk Krack, Cruise and costar Rebecca Ferguson trained their bodies and minds.

"Basically what I'm doing is taking Tom and Rebecca through a breath-hold special operations program," says Krack. "It's a program I've developed for militaries. And what we're really trying to do is we're developing their ability to hold their breath under extreme conditions."

How extreme?

"You have to overtrain for a sequence," says Cruise. "We were doing up to six-and-a-half minute breath holds."

Which left the crew gasping -- with fear.

"Tom is very comfortable underwater," says Krack, "and he likes to challenge the crew by staying under longer than he should on a breath hold and get us all worried."

"Mission: Impossible - Rogue Nation" will be released on Digital HD on Nov. 17 and on Blu-ray combo pack/DVD/On Demand as part of the "Mission: Impossible" five-movie Blu-ray collection on Dec. 15.