One-Armed Surfing Star Says Upcoming Biopic Is 'Spot On'

March 29, 2011— -- Professional surfer Bethany Hamilton became an international sensation when she lost her left arm and nearly died in a vicious shark attack off the coast of Hawaii more than seven years ago. Now the story of her harrowing attack and comeback is about to premiere on the silver screen.

"I definitely would allow the shark attack to happen," Hamilton said. "The thing for me is I know that God allowed it to happen because of all the good stuff that has come from this terrible experience."

"Soul Surfer," which opens in theaters April 8, is the movie adaptation of Hamilton's 2004 book about her life, "Soul Surfer: A True Story of Faith, Family and Fighting to Get Back on the Board." The 21-year-old Kauai, Hawaii, native said she has been blown away by what has happened to her since losing her arm.

"My family and I just [had] a pretty humble lifestyle," she said. "Everything just changed after the shark attack."

After the movie got under way, Hamilton said she helped choose actress AnnaSophia Robb to play her. Robb is most known for her leading role in 2007's "The Bridge to Terabithia."

"She's playing me when I'm younger, you know, so she's about the height I was." said Hamilton, who now towers over Robb.

Robb called it the roll of a lifetime, and said, "I heard about Bethany's story when I was younger, and I was so shocked that she could get back in the water after something that traumatizing happened to her."

Hamilton did all of her own one-armed stunt work for the film. She also taught Robb how to surf and how to get over her own fear of sharks.

"Every time I went out I was always looking in the water," Robb said. "I was kind of nervous. Bethany told me, just don't look down. I figure, if she can still get back out there and not worry, than I should be able to as well."

The movie's shark attack scene lasts only a few seconds, but Hamilton said it was incredibly accurate.

"It's really spot on," she said. "It's not really hard for me to watch, but I see it and it's like exactly how it happened. It was just really quick. I didn't see anything."

The surfing champion first told her story to "20/20" weeks after the October 2003 attack on Halloween morning. Thirteen years old at the time, Hamilton said she was at her favorite spot, called "the Tunnels," when her life changed forever.

"I was lying on my board sideways. And then ... the shark came up and grabbed ahold of my arm," she told "20/20" in a November 2003 interview.

"And then, I was holding onto my board, with my thumb, because I probably didn't want to get pulled under. It was like pulling me back and forth, not like pulling me underwater. Just like, you know how you eat a piece of steak? It was kind of like that. And then it let go. And then went under. Then I looked down at the water, and it was like really red, from all the blood in the water."

Hamilton said the attack happened so quickly that none of the surfers around her ever saw the creature or her struggle with it. But the attack severed her left arm just below the shoulder.