A film adaptation of the iconic 1990s TV series Baywatch has been in the works for years, and it's finally here, with Dwayne Johnson assuming the red trunks to play Mitch Buchanan, David Hasselhoff's character in the show (with the Hoff himself appearing in a cameo as his mentor). Johnson says that turning the series into a film allowed them to emphasise what made the show so hugely popular.

The Rock and Zac on the Baywatch set

"Baywatch is all about gratuitous boobs, bums and abs," Johnson laughs. "We worked hard to make sure the flesh quota was high. And we are far dirtier than the show ever was! Obviously the show was a family show on at family time of day, but in the movie we could be dirtier. Actually, I think people are going to be shocked that Baywatch has got dirty, but there are a lot of laughs. Plot was important - don't get me wrong! But so was sorting out our slow-motion runs."

For his sidekick, Johnson has the almost impossibly fit Zac Efron as Matt Brody, a disgraced Olympic champion swimmer. "Let's take a moment to look at the shape that this guy came in," Johnson notes before laughing again, and adding, "I don't get in shape; I stay in shape."

And Efron returns the compliment. "This guy motivates you to work out," Efron says of The Rock. "He's so cool. He's like the coolest dude in the world. He's an animal! In real life, if you look in the mirror, there's nothing wrong with you. But if you're The Rock, what the heck? Where'd you come from?"

Efron admits that he had to work to keep up with Johnson. "That's as much a part of the character as anything," he says. "I wanted to be accurate and to look like an Olympic athlete, so I started training like one. I trained my arse off. It was really, really hard. Although to be honest, wearing heels was one of the most difficult stunts in the movie!"

He also found it challenging to be on a set where improvisation was encouraged. "There's always a version of what was on the page," Efron says. "Then sometimes if you go off on a tangent and you don't hear cut, you just keep going. Sometimes those would lead us very far in this movie! Some of the funniest things are actually when we would go past the dialogue and we were just trying not to laugh."

Watch the trailer for Baywatch: