It is a fear that has been in the back of every beachgoer's mind since 1975, when Steven Spielberg's Jaws brought the terrors of the deep to the silver screen.
When you enter ocean waters, you're not the top of the food chain anymore.
But when fear became reality for one Concord mother, faith and will to survive kept her going.
Fighting Her Way Free
Tiffany Johnson, one courageous mother of three, was on vacation with her husband, James, in the Bahamas back in June when they decided to do some Caribbean snorkeling off the beaches in Nassau.
With her husband still in the boat and her in the water, Johnson was suddenly attacked by a large shark that had clamped down onto her right arm.
"Honestly, it felt like I had bumped into something. I wasn't alarmed. It didn't hurt. So I looked to the right to see what (I) bumped into and that was when I was face-to-face with a shark."
Fighting her way free, Tiffany saw part of her arm was now gone. She knew she needed to get back to the boat. She says it was a miracle she survived.
"God-given strength rose up and came inside of me and I remember thinking this is not the end. He is not going to take my life," she said.
James tied a beach towel around his wife's arm and the couple made their way to a local hospital.
In the weeks to come, Tiffany would be transported back to the United States where she would undergo multiple surgeries on her arm, with hope of saving her nerves and muscles to be used by a fitted prosthetic.
"I didn't even know that was possible!"
With part of her arm now gone, Tiffany was to be fitted with a prosthetic arm. However, the science of prosthetics has come a long way from simply plastic placeholders.
"There's a new surgery, and it's call targeted muscle reinnervation," said Dr. Glenn Gaston of OrthoCarolina in Charlotte, where Johnson has her appointments.
"What we do is take the nerves that used to control the hand that have been amputated, so we can take that nerve into a different muscle. So when her brain tells her thumb to move that muscle will fire."
Her surgeons will use the nerves left inside her arm to communicate with the new prosthetic.
Tiffany was astounded at the idea when she was first told.
"I didn't even know that was possible!"
However, she knew that it would take some time and multiple visits before she could be fitted with her new limb.
"It is a step-by-step process, Johnson said. "In due time, it will be there."
A 'Proud Mama Moment'
In the meantime, the Johnsons have tried to explain what happened to their three children in a way they best see appropriate.
"What they do know is Mama had an accident in the water."
So to do something to help Mama, the kids did what so many other kids do: They opened a lemonade stand hoping to raise money to help get their mother a new arm.
That's when local radio station KISS 95.1 stepped in. When they heard about the kids, the station wanted to help.
"We wanted to do something," said KISS radio spokesperson Roy Brown from behind the stand. "We can blast out that we are here broadcasting live and get people to come out and help mom."
PHOTOS: Tifanny Johnson's story of survival and recovery
Johnson looked on as her kids sold lemonade to people who stopped at the local Concord 7-Eleven.
"It's a proud 'mama moment' when they want to jump in and help mom," Johnson said.
It's Tiffany's positive attitude and upbeat spirit that have touched many who have heard her story.
"God in me is what is shining through so what people see is not me. They see Jesus."
A Positive Light
For the first time Tiffany Johnson is putting on her prosthetic arm. "The kids tonight want to decorate it. Draw all over it like it’s a cast ya know."
Tiffany's doctors are amazed not only with her progress, but her attitude as well.
"I think she's inspiring a lot of people," said Bryan Loeffler of OrthoCarolina.
Plus, her new hand was responsive almost immediately after everything was switched on.
"They were like, 'just think about open and close on this side' and I'm like it's working?"
One of her doctors said the rate of her progress is ahead of schedule.
"Sensors placed around the arm were actually able to pick up some signals already, and it's only been about four or five weeks. So she's ahead of pace right now."
And with such a positive attitude, Tiffany continues to be an inspiration to so many who hear her story.
"That's only God. That he can take something so terrible and turn it into something beautiful."