Photo finishes are for horse races, the 100-meter dash. But a 12.5-mile swim? The odds against having a long-distance stroke-and-kick come down to 1.13 seconds are off the charts.

But that’s what happened Saturday afternoon at the College of the Florida Keys Swim Around Key West, when Chris Allshouse of Canton, Ohio, came from behind to win the men’s overall championship in a time of 4:34.44.

Tommy Wolinski, who didn’t take a breath with his final 10 freestyle strokes and was so close to Allshouse that he “could see the stars on his Speedos,” got tapped out with a 4:35.53 time.

“I can’t believe how close that was!” Allshouse told Wolinski, from Wallington, N.J., beneath the awards tent at Smathers Beach, which just happens to be the same spot where Diana Nyad completed her historic, 110.86-mile swim from Cuba in 2013.

That duo provided the drama, but overall champion Carlie Rose, 18, turned in the flat-out brilliance.

Rose, a Harvard-bound swimmer who was on a state championship 4X100 relay team at Oviedo High this year, smoked the field with 4:16.54 time. The second overall finisher was Sandra Frimerman-Bergquist (who competed collegiately at Northern Iowa and St. Cloud State) of Bloomington, Minn., in 4:24.48, about eight minutes behind Rose.

Mother Renee Rose and friend Dana Andrews escorted Carlie while paddling a kayak, which is one of the race rules, and received some unexpected news from a fan viewing the stretch from the Gulf of Mexico toward the Atlantic Ocean from atop the Cow Key Bridge.

“You’re the first solo swimmer!” the race enthusiast shouted.

Mom and Andrews relayed the news to Carlie: “You’re first!”

Carlie said, “I thought, ‘That’s great.’ Honestly, I just wanted to finish. And then I knew I had to finish. There was no turning back then.”

Carlie finished nine-hundredths of one second behind the four-person relay winners, the all-male Wahoos from Wellington in Palm Beach County. D.J. Gallagher, Scott Loder, Len Lindahl and Thiago Caze each had to swim 25 percent of the distance she did, and Carlie still came that close to their time.

“I was in the best shape I could be in right now,” said Carlie. “I swim with my dad (Charlie), my high school coach. We won the state championship as a team my junior year. He did this race, too, and his time was 5:09. That was my goal, just to beat my dad.”

Will she rub in the fact she finished about 52 minutes ahead of his time?

“No,” she said, while smiling, “he was 40 when he did that.”

She said Dad gave her his conch trophy awarded several years ago, and she said, “We might do a trade. I might give him mine.” Hey, Father’s Day is coming up Sunday.

Carlie said the stretch run, heading for the finish at the same Smathers locale where the race began at 9 a.m., was the toughest.

“You’re 11 miles in at that point and the waves were beginning to pick up,” she said. The 84-degree water temperatures were taking a toll, too.

Carlie said her closest competition was someone she took notice of not far from the marinas while churning through the Gulf.

“We were close there,” she said.

But there was no catching Carlie. She tapped the yellow buoy at the 10th and final channel marker at Smathers, waded in through the Sargassum seaweed that cluttered the area near shore, and immediately hit the showers at the bathhouse.

“That was very refreshing,” she said.

Carlie had never tackled this distance, but did finish eighth in mid-April in the 10-kilometer (6.2 miles) swim at the USA Swimming Open Water National and Junior Championship at Fort Myers Beach with a time of 2:13.11 in the junior race portion.

She did the 200- and 500-yard freestyle for Oviedo, and was a state finalist in both events, finishing seventh (1:50.54) and fourth (4:54.98), respectively, while swimming the third leg on the state championship sprint relay.

“Now I’m going to Harvard in August and I’ll swim for them, too,” Carlie said. “I’m not entirely sure what I’ll study, but I’m thinking something biology-related. Growing up, I was always interested in marine biology, and I haven’t taken that out of the equation yet. I’m also interested in (cures for) infectious diseases.”

Her mother said, “I’m just super proud of her. She works so hard.”

The family takes vacations in the Florida Keys “every chance we get” and usually stays in Marathon.

She said the conch trophy — which The College of the Florida Keys event organizer Lori Bosco informed swim winners were imported from the Bahamas — “has more sentimental value” for her, and will probably be left at the family home outside Orlando rather than risking damaging it en route to college in Cambridge, Mass.

“I want to thank everyone who made this race happen,” said Carlie, “especially after a year of being locked inside, too.”

Bosco said this race, originated in 1996, was for both 2020 and 2021, adding that nearly 200 entered.

None of the competitors put up a more spirited effort than Allshouse, 51, a manufacturers sales representative, and Wolinski, 27, a chemical engineer.

“We showed up well for the North,” Wolinski told Allshouse as they smiled and congratulated one another for a great race.

Wolinski added, “In the last 50 yards, he pulled up next to me and it was some race, a photo finish, I guess.”

Allshouse’s response to the narrow victory: “Shock! Surprise.”

He had his wife, Julia, paddling in the kayak to his immediate right.

“I breathe to my right about 900 times per mile,” he said. “I smiled with every breath and she smiled back at me. But she stuck out her tongue one time (laughter).

“But she was awesome. That’s the hardest part of this gig, the kayaking.”

He said swimming this race in 2016 better prepared him for the challenges this time. He added that staying hydrated was critical on a hot day with very warm Gulf and ocean water, noting that he used a powder mix, Infinit, to supply electrolytes, salt and potassium.

Swim Around Key West, Allshouse noted, was great preparation for the 28-mile open water challenge he’ll take part in on July 25 in the Ka’iwi Channel Swim between Molokai and Oahu.

The course began at Smathers and headed toward Southernmost Point to Key West Harbor, continued through the harbor, and exited under the Fleming Key Bridge, and through the city of Key West mooring field around Sigsbee. Then swimmers headed to Cow Key Bridge and made their way toward Key West International Airport before returning to finish at Smathers.

Allshouse said he swam the 200 individual medley and 100 butterfly at Perry High in Massillon, Ohio.

“But this was total freestyle,” he said with a smile. “I did do a little backstroke to show off for my wife, though.”

It was fun. It was competitive. And it was an endurance swim race to remember.