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."