NAOMI WATTS is deservedly getting Oscar buzz for her role as a mom trying to save her family during the 2004 Indian Ocean tsunami, but Tom Holland, who plays her teenage son in the movie, matches her step for soggy step.

Not bad for a 16-year-old in his first film.

And talk about versatility, Holland's previous role was in London's West End, as a ballet dancing miner's son in "Billy Elliot."

"I did 'Billy Elliott' and I enjoyed it thoroughly," Holland said in September during the Toronto International Film Festival. "I loved it. And I've done pretty well since then with a lot of fun experiences that have really built a base for me.

"When I was young, my mom realized I could dance and hold a beat, and I really danced just for fun. It was good exercise. And then 'Billy' came along, and they taught me how to act and sing and dance, which was great. And from there it's been a bit of a snowball effect."

Really more of a tidal wave.

Holland said he was planning to leave the show when "The Impossible" director J.A. Bayona saw a video interview of him talking about his experience with "Billy."

"Within the space of six weeks," Holland said, "I was in Spain drowning in a pool."

Actually, not drowning, thanks to the rigors of his dance role.

"Because I had just come out of 'Billy,' I already was in good shape. And I don't think I would have been able to do the shoot without 'Billy,' because what we did was very demanding. 'Billy' had given me the stamina because we had such amazing trainers. I was very lucky in that sense."

Holland said he got to meet the family "The Impossible" was based on, and "we had a few bonding sessions."

"They were on set as well," Holland said, "and everybody really worked hard for them. They would never hesitate to give you advice, and they were a very lovely family."

As for the differences between acting onstage and screen, Holland said he owes a lot to Watts and his movie father, Ewan McGregor.

"With 'Billy,' you have to perform to everyone in the audience," he said. "There are people 17 meters away, and you have to make sure that they can read your face. But on film, the camera could be 5 inches from your face, so you need to be subtle and everything has to be natural, which was a big change. But Naomi and Ewan gave me advice that no one else can. It was great. I was really lucky."

Since filming required so much water work - on many days the actors were in and out of huge tanks of cold water - Holland said Bayona "would shoot the rehearsal in case something amazing happened."

He added, however, that the actors didn't need much rehearsal in the giant pools, because the waves would just take you. "You'd let your body do what would naturally happen," he said.

"When you see us go down [under] the water, that's two different shots from two different pools on two different days. It's amazing. When you see the hotel get destroyed, that's real. They built a model to a third of the size and just destroyed it.

"It's really terrifying to watch."

And all those tree limbs and car parts floating in the water?

"They're all foam," Holland said, laughing. "It took me ages to get over that. I'd get hit with a plank and I'd be waiting for the pain . . . "

But although the garbage left behind by the movie tsunami was foam, the water and Thailand locations were real.

Holland said the hotel where the actors stayed was the rebuilt hotel where the real family had stayed, and the hospital where Watts' character recuperates is the actual hospital where the real mom spent months in recovery.

"We were filming on the top floor," Holland said, "and my dad and little brother were on the bottom floor of this functioning hospital."

And was this functioning hospital really that dirty?

Holland nodded. "It was filthy."