Despite the attack, Hamilton, 19, has proved she could still compete with the best of them, jumping right back in the water one month later.
"To me, it's like never getting in a car because you're afraid of a collision. Not surfing doesn't work for me," she said.
On the professional surfing circuit, the Kauai native has become known for her courage, positive attitude and fierce competitive spirit.
"One arm might handicap me a little in competition, but I just work with what changes I know I have to make, and I'm pretty used to it now," she told ABC News. "It mainly depends on the wave conditions...I only get half the waves everyone else rides, so mine have to be good!"
Hamilton first told her story to "20/20" after the October 2003 attack. Many doubted if Hamilton -- then 13 years old -- would ever be able to surf competitively again, but she refused to let her story end in tragedy.
"I get tons of letters...people saw that I didn't give up on my dreams," she told "20/20" in a November 2003 interview. "I kept surfing -- it helped them out a lot and that just shows that good can come out of bad stuff like this."
It's no wonder then that Hamilton's biggest challenge and the incident that propelled her to national fame happened in the water. Born into a family of surfers, Hamilton had been catching waves and trophies since the age of 8 before her harrowing attack.
Suzanne "Bobo" Bollins, a fellow surfer and long-time family friend, says she always knew Hamilton had what it takes to be a champion.
"I consider her a little ocean person. I'd say she has salt in her blood," Bollins said. "She lives and breathes the ocean. She gets the big waves. She doesn't mess around...I have said to myself, 'There's the next world champion.'"
On Oct. 31, 2003, the water was glassy and calm at Hamilton's favorite surf spot, known as "The Tunnels," when her life changed forever.
"I was laying on my board sideways. And then...the shark came up and grabbed a hold of my arm," she told "20/20."
"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."
It 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.
"I think I figured out that if I panicked, then things wouldn't go as good as if I was calm," she said.
"I was praying to God to rescue me and help me," Hamilton said. "And then, I had this one pretty funny thought, I think. I was thinking, 'I wonder if I'm going to lose my sponsor.'"
The shark took a 16-inch bite out of her board and Hamilton nearly died from blood loss.
"When I first saw her in the hospital that morning she looked really pale but she had a brightness in her eyes that I could just say, 'You know, she's going to be alright,'" Bethany's mother, Sherry Hamilton told ESPN.
Local fisherman Ralph Young was determined to catch the creature. He laid a trap about 50 feet off the reef, where Hamilton was surfing and caught a 14-foot-long tiger shark. Close to 1,400 pounds, Young was sure he'd captured the shark that attacked Bethany.
"When we took the outline of the bite in the board and compared it to the jaw, it fit perfectly," Young said.
Hamilton has drawn as much admiration from her community after the attack as she had before.
"I guess since I handled the situation so well, that people have taken me as a role model, but I don't like feel like one," she said.
Friends and family say Hamilton's grit and spirit aren't qualities she's acquired since her accident, but have always been there. Her father, Tom Hamilton, says she never had a "pity party" over losing her arm in the attack.
Instead, just a month after a shark took her left arm, her passion brought her back into the water. "I was just stoked to be riding the wave. After that I just had like tears of joy paddling back out," she said.
But, when she first returned to surfing, the champion had to re-learn a sport that had become second nature. "Just learning with one arm and adapting to not having two there," Hamilton said.
But she was determined. Hamilton described surfing with one arm like doing "a one arm push-up."
To help her paddle out to the waves, her father came up with the idea of putting a handle on her board so she could catch her balance.
"Surfers use both hands to grab the sides of their board and push themselves up. Bethany has to do it with one," he told "20/20."
"Every time I would go out there, I would learn something new...I kept practicing just on smaller waves, just standing up and figuring out how to catch it and all that and each time I felt better and better about my surfing," she said.
Her positive attitude won her a 2004 ESPY Award from ESPN for Best Comeback Athlete of the Year and a special Teen Courage Award. She's now ranked among the top 10 professional women surfers in the world.
On top of physical hurdles, Hamilton has overcome psychological ones as well -- namely the fear of another attack.
"You never know" if it could happen again, she said. "When I'm feeling scared I just sing a song or pray...Or [I] just try to ignore it and, you know like, it's always in my mind, and it always will be, but I got to keep my mind on having fun, and just surfing."
Hamilton does say she has become a bit more cautious.
"I just do my best to be smart when and where I surf. I don't go out if it's questionable (shark sighted, murky water after a storm, etc.). And when I'm out, I head in if I get scared or think I saw a shark."
She says she sees two to three sharks per year in the water; once, a 5-foot hammerhead shark swam right under her board, forcing her to come in to the beach.
Over time, Hamilton has become comfortable with her physical disability. Early on, she had a prosthetic arm custom made for her, but she chooses not to use it.
"Living in Kauai, everybody knows who I am and it's not really going to make me more confident having a real arm and a fake arm," she said.
"It's not that I don't like it, but it doesn't really come in handy, because living in Hawaii, I'm running around and it's not like it's waterproof. And it doesn't help me paddle any faster."
Bethany travels the world for surfing competitions, but also for causes she believes in. She went to Thailand with an organization called World Vision to help young children who were devastated by the tsunami disaster. With her unique experiences, she was able to work with children to overcome their fear of the ocean.
Spending countless hours in the ocean, Hamilton brought her love of the environment to her career. She runs a thriving business that includes inspirational speaking engagements, movies, books, videos, fragrances, accessories and a line of environmentally friendly footwear.
With each product, she includes an encouraging message about environmental awareness, like taking care of local beaches with trash pick-up. It is her hope to inspire new generations to "Be Ocean Minded!" which is her company slogan.
A Hollywood movie based on her biography "Soul Surfer" is in the works.
For more information on Bethany Hamilton, visit her Web site, www.bethanyhamilton.com.