Bethea happened to be scalloping alongside her brother Rhett Willingham, a firefighter and emergency medical technician, who raced to help her.
Together, the siblings fought off the 9-foot shark and got Bethea back into a boat and to land, where she was airlifted to a hospital in Tallahassee, about 80 miles northwest of Keaton Beach, where the attack occurred.
Bethea, now 18, ultimately lost her right leg in the attack and spent multiple weeks hospitalized, and then in rehabilitation learning to live life as an amputee.
On July 1 of this year, Bethea returned to the same beach where she was attacked by the shark, and she got back in the water, again alongside her brother.
"I felt completely safe. It felt perfectly normal," Bethea, who is from Perry, Florida, told "Good Morning America." "It didn't make me sad or anything. I didn't get emotional. It was just like [a] back to just normal kind of thing, hop back into routine."
'I belted as loud as I could'
That return to the ocean, which took place nearly one year to the day of the shark attack, marked a year of recovery for Bethea, who said she remembers every detail of her encounter with the shark.
"When it latched on and pull me under with my calf, I remember that exact moment," Bethea said. "It felt like someone just pulling you under water, like that scary sensation when someone just touches you in the water. I didn't feel any pain or anything the entire time it bit me other than when I tried to pry it off with my hands."
Bethea said she has long been a fan of shark content on TV and online, so even in duress, she remembered that she should try to poke the shark's eyes or punch its nose to get it away from her.
When she saw that wasn't doable due to the way the shark attacked her, Bethea said she just started to scream.
"My brother was the one that heard me scream ... and when he turned around, I was actually pulled under the water by the shark," she said. "I came back up and I was screaming for him."
She continued, "It's almost like when you're in a dream, and you're trying to scream in a dream, and it feels like nothing's coming out. That's what I felt like in that moment, so I belted as loud as I could."
Bethea said a nearby boater also heard her scream and came to the siblings' aid.
When she and her brother got back onto the boat with the help of the good Samaritan, Bethea said they saw that "everything was gone" from her right thigh.
Surviving six surgeries with a goal of walking at homecoming
Once Bethea was airlifted to a hospital in Tallahassee, she faced the next round of survival: undergoing six surgeries.
Ultimately, doctors reconstructed much of her right thigh and amputated her right leg above her knee, allowing for her to use a prosthetic.
While recovering in the hospital during what should have been the start of her senior year of high school, Bethea said she focused on staying positive.
"What my dad used to tell me in the hospital [was], 'Today is going to be a good day,'" Bethea recalled. "Even if it's not a perfect day, just find one good thing out of your day to keep you going ... just be grateful."
And when she was moved to a rehab center, Bethea said she set a goal to be able to walk on her own at her high school's homecoming celebration in the fall.
"During homecoming week is when you walk in the fancy dresses down the football field," she said. "That's something I've always loved doing, and the parade, and I wanted to be able to do that again one last time for senior year."
Prior to the shark attack, Bethea said she had been a cheerleader for her high school, and an active person who loved exercising and weightlifting.
She thinks those hobbies served her well in her recovery, as she was able to adapt to her prosthetic leg quickly and return to school in person in September, just three months after the attack.
When she was named to her high school's homecoming court, Bethea was able to walk on the football field with her prosthetic leg.
"It was different, but I was able to do it," she said. "I walked on the field with my prosthetic perfectly normal, without crutches or anything."
Bethea was also able to cheer at one final high school football game with her team. She said her family and friends make sure she doesn't miss out on any activity.
"If I'm wanting to go on a four-wheeler or something, we'll do that and they'll make sure I'm OK. Or if we're going on the boat, they'll make sure everything is good ... They'll carry me up the stairs," Bethea said. "'I'm still doing the stuff I used to do, it's just little slower and it's a learning process, but I still do it my own ways."
In May, Bethea marked another milestone: walking on her own at her high school graduation.
Welcoming a new life after almost losing her own
A few weeks before her high school graduation, Bethea said she learned of a surprise that will shape the next phase of her recovery.
She found out that she is pregnant and expecting her first child in December.
"It definitely wasn't something I planned, but like I've said, God works in mysterious ways," Bethea said of becoming a first-time parent with her boyfriend. "Maybe it's just time for me to be a mom. I'm very excited."
She noted that she plans to give birth at the same hospital where she received much of her treatment after the shark attack.
"It's crazy to be bringing a brand new life into [the world] when mine was almost gone," Bethea said. "It's kind of crazy how that works."
Also next for Bethea is continuing her education at a local community college, where she hopes to earn her associate degree and then go onto study to become a physical therapist, a career inspired by the care she received.
"It's not always been something I wanted to do," she said of becoming a therapist. "But once I got to rehab and I saw all the people in there, including myself, and seeing how I progressed through it, it kind of made me want to do it and help out others."
Bethea said she's also taken on the surprising role of being a high-profile person whose story, she has learned, has inspired more people than she ever imagined.
"I'll be two hours away from my house, in a random city in Florida, and they'll recognize me and say, 'Your story has really touched me. I've been following your story. You really inspire me,'" she said, adding, "I don't really think anything of it, just because it happens so often, but it is really cool just how many people I have touched, I'm pretty sure."
Bethea added that while her chance encounters with strangers are often emotional, many times, they begin with a funny interaction.
"Some people will be like, 'Where do I know you from?' And I'm like, 'I got attacked by a shark,' and they're like, 'Oh yeah, that's it,'" she said. "It's kind of funny and humorous at times, and other times, it's just like, I don't realize how many people I have touched and what I've done."
Part of Bethea's mission, she said, is to keep people excited about the ocean, as she is, rather than scared.
Bethea's shark bite was among the 57 unprovoked shark bites worldwide in 2022, most of which occurred in the United States and Australia, according to the University of Florida's International Shark Attack File. Florida, where Bethea's attack occurred, had more reported shark bites than any location in the world.
Bethea said she encourages people to know their surroundings in the water, never fish or swim alone and to use a shark repellent device if possible.
"You can't just be mad at the ocean when you're in [sharks'] territory," Bethea said. "They know what they're doing. They know what they want to eat. You've just got to be mindful of that."