Bradley Cooper is baring all.

The 45-year-old actor opened up in a new interview about filming nude for his role in Guillermo del Toro's "Nightmare Alley."

 The actor plays a con man Stanton Carlisle and spent a total of six hours filming a bathtub scene naked in one day.

"I can still remember that day, just to be naked in front of the crew for six hours, and it was Toni Collette’s first day," Cooper recalled in a new interview with KCRW.

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Bradley Cooper in "Nightmare Alley." (Nightmare Alley Official Trailer )

That specific day of filming was "pretty heavy," he added.

"The content of what the movie is, what we were exploring, in order to do it in a real way, it demanded that we’d be naked emotionally and soulfully," he continued.

Although Cooper is a seasoned actor, he admitted stripping down to nothing for the role was no easy feat. The "A Star Is Born" actor confessed it was a "big deal" for him. 

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NEW YORK, NEW YORK - FEBRUARY 05: Bradley Cooper speaks onstage at Oprah's SuperSoul Conversations at PlayStation Theater on February 05, 2019 in New York City. (Photo by Jamie McCarthy/Getty Images)

Bradley Cooper is opening up about what it was like to film nude for his role in "Nightmare Alley." (Jamie McCarthy)

"I remember reading in the script and thinking, ‘He’s a pickled punk in that bathtub and it’s [the] story. You have to do it.’"

In terms of preparing for nudity on-camera, he likened it to "putting on a miner’s kit, hat and flashlight, and looking at each other and then going down in the tunnel, knowing that you may be excavating a route that won’t ever get you to the end that day but you come back up and go down again the next day."

Cooper is no stranger to getting vulnerable in front of the camera. In an interview with The Hollywood Reporter in November, he addressed the previous dating rumors about him and Lady Gaga, stemming from their performances in "A Star Is Born."

"Just from a personal standpoint, it reduces the anxiety level," Cooper told the outlet, referring to the way the two stared into each other's eyes as they performed "Shallow" at the Oscars.

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FILE - This file image released by Warner Bros. Pictures shows Bradley Cooper, left, and Lady Gaga in a scene from "A Star is Born." The film may be the lead nomination-getter Tuesday, Jan. 22, 2019, when nominations to the 91st Oscars are unveiled. (Warner Bros. Pictures via AP, File)

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"They kind of fall in love in that scene in the film," he added. "It’s that explosive moment that happens to happen to them on a stage in front of thousands of people. … It would have been so weird if we were both on stools facing the audience."