John Cena is a muscled merman in ‘Barbie’ movie: ‘A happy accident’

He’s trading WWE for “Under the Sea.”

Wrestling icon John Cena stopped by the “Today” show Monday where he revealed how he got cast as a merman in Greta Gerwig’s upcoming “Barbie” film.

According to Cena, 46, the opportunity to be in the highly anticipated film came in the form of a chance encounter with “Barbie” actress Margot Robbie, 32, who was filming her movie across the street from his latest “Fast & Furious” installment.

“It was a happy accident, and I think ‘Barbie’ and ‘Fast X’ share a lot of parallels,” Cena said during the “Today” interview. “Their cast list is amazing. The ‘Barbie’ cast list is amazing. The ‘Fast X’ cast list is amazing. It was a chance maybe to [say], ‘Hey, would you guys be willing to have me if I could do something?’ “

Cena said that he told Robbie he “would do, pretty much, whatever you guys need ’cause I really enjoy the movie.”

Fortunately for the athlete, his “Suicide Squad” co-star made “a lot of the decisions” regarding casting and was later asked if he would be a merman.

The Post reached out to Cena and Robbie for comment.

When pressed by host Hoda Kotb, Cena recalled the experience of being on the film’s set as “surreal.”

“Honestly, I think people are going to have a lot of fun watching this,” he added. “I think it’s going to take a lot of people by surprise. [It’s] a very interesting take on everything but I was super lucky and it’s tremendously surreal.”

The “Playing with Fire” star revealed last week that his official audition for the summer flick initially did not go well.

“I tried and got rejected,” Cena said on SiriusXM’s “Pop Culture Spotlight” with Jessica Shaw. “They were putting out open casting for the movie. I get it, I wasn’t a piece for the puzzle.”

“I think a lot of times people think, ‘Oh, he wouldn’t do that,’ ” continued Cena. “I don’t think there are any small parts. A chance is a chance. An opportunity to show your skill or develop a new skill, that’s fantastic. That’s why I want to do all this stuff, so I think once they realized I would just be grateful to be involved, they were like, ‘Yeah, you can do this.’ “

Cena will flip his fin alongside pop star Dua Lipa who was revealed to be playing the mermaid version of the popular Mattel doll.

Gerwig’s film has spawned unending waves of social media frenzy.

In April, the film dropped a full trailer featuring the entire cast as well character posters for all the different versions of Barbie.

The trailer later became the subject of Twitter memes about Robbie’s interpretation of the doll’s feet causing some to wonder if the director had a foot fetish.

“Barbie” is set to party its way into theaters July 21.