On a stacked Team USA Olympic swimming roster, no one is quite like Katie Grimes. 

No one is qualified for both the 1,500-meter freestyle, the longest event in the pool, and the 400-meter individual medley, a grueling parade of all four strokes. And the 10k marathon swim. No one except Grimes – now a two-time Olympian who will be the first American woman to compete in the pool and open water at the same Olympic Games.

She’s also just 18 years old.

"I've done open water just about as long as I've done pool swimming, so I've just always wanted to be able to swim the open water (event) in the Olympics," says Grimes, whose shortest race at the Paris Games is about four-and-a-half minutes while her longest is two hours.

"I never wanted to pick one over the other."

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Three years ago, Grimes was the youngest overall Team USA athlete at the Tokyo Olympics, swimming the 800-meter freestyle in her first international competition. She finished a disappointing fourth, barely missing the podium as Katie Ledecky completed a three-peat Olympic championship.

This time around, Grimes didn’t bother messing with what she called a "congested" 800 international field. Though if you told her three years ago she’d drop what she once considered her best event, she never would have believed it.

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Instead, Sandpipers of Nevada head coach Ron Aitken helped Grimes plot a path to the Olympic podium, prioritizing her strongest events. Plus, skipping the 800 gives her more time to prepare for the 10k in the Seine River eight days after her last potential final in the pool.

Grimes was the first Team USA athlete to qualify for Paris back in July 2023 when she won bronze in the open water 10k at world championships in Japan. 

At U.S. Olympic swimming trials in June, she won the 400 IM to officially qualify in the pool before making it in the 1,500, when she finished second to Ledecky. 

"She always downplays her success, and sometimes I wish she wouldn't because I just want her to be really, really proud of herself and really realize the full scope of what she's accomplishing," says now-two-time Olympian Regan Smith. 

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Katie Grimes' insatiable hunger to win

It was about 5 a.m. when Katie Grimes strolled into one of her older brother’s swim practices. She was 11 or 12 years old, Aitken recalls, and aiming to break a record at an upcoming meet. So she wanted additional practice.

Aitken reminded her to have fun because extra hours in the pool would surely come as she aged. But he said, even then, he could see her insatiable hunger to race and win.

"She puts a tremendous amount of pressure on herself to be a lot better than she is currently, and that kind of keeps her from being as good as she can be," Aitken says. "That just goes along with age. I think, right now, she's still not at a place where she's been able to master pressure yet."

It’s one of the many ways he’s reminded she’s still a teenager. But hardly an average one. She’s "an old soul," her mom, Shari Grimes, said – and one who was even resistant to getting a phone ahead of the Tokyo Games until Team USA strongly emphasized it.

Inheriting a competitive streak as the youngest of seven in an athletic family, she lives at home with her parents in Las Vegas and just graduated from high school. She’s a straight-A student who has yet to announce her college choice – though she said she’s made a decision and will likely declare after Paris.

Soft-spoken and silly sometimes, she's on social media but would rather spend her free time listening to Fleetwood Mac or leisurely driving around in her coveted orange 1969 Chevy Corvette Stingray. She indulges in retail therapy, like recently buying a Skims towel-esque sweatshirt, despite its impracticality in scorching Vegas temperatures.

When it’s time to train, she embraces her workhorse mentality, calling it "the most comforting thing."

"(Grimes) is incredibly impressive – her ability to train and compete for open water, 400 IM, 1,500 free, she’s able to do it all," Ledecky said. 

"She just keeps going, and she has such a good attitude about training and about racing and just is fearless when it comes to signing up for those events and racing the very best."

Training for events largely on opposite skill spectrums, Grimes heavily relies on Aitken for guidance. Even for the 10k, all of her swimming work is in the pool, racking up between 65,000 and 85,000 yards – or up to about 50 miles – a week.

She might do a distance freestyle workout in the morning, followed by IM and stroke work in the evenings. The weak link in her 400 IM is breaststroke, so she trains to build up a lead on the butterfly and backstroke legs, hoping she doesn't get caught on in the second half. 

"It's really just in the competitions where you get that (open water) experience," Grimes says. "Building up that stamina, building up the endurance – it's very easy to work that in the pool. …

"In fact, it's probably even easier to train that in the pool just because you can blog exactly how much you're doing and how fast you're doing it."

That’s where Aitken and his Excel sheets come in, tracking workouts, stroke counts, heart rates and stress levels. 

She can handle the absurd yardage, stroke work and sprint drills. She’ll do whatever workout Aitken writes on the board, wanting to train for as many events for as long as she can. She loves strength training, welcoming speed work to improve her reaction times off the block. 

The real challenge, she says, is competition time when she has to delicately balance prep, racing and recovery in between monstrous events. It didn’t help that she recuperated from pneumonia about 10 days before Olympic trials, Shari said, and was extra nervous because she was expected to make a second Olympic team.

At trials, she had about a 25-hour arduous stretch where she raced 2,500 total meters, plus warming up and down. But she views it as another level of preparation with the trials schedule closely resembling the one in Paris. 

"Even though she's 18 and I'm 22, I look up to her in a sense as well because she is so versatile," Smith says. "She makes it look incredibly easy, and she's kept a very, very humble demeanor through it all."

Katie Grimes' called her shot

Katie Grimes called her shot when she was 10 years old. After cheering for her brother at 2016 U.S. trials, she decorated a kickboard that still hangs on a wall in the Grimes’ house. On it is a powerful message: "2020, I’m going to be there. Keep strong, keep swimming."

"She was watching all these kids make the Olympic team, and she looked at us, and she goes, 'I'm doing this next time,'" Shari recalls. "She just was laser focused from that point on."

The Paris Games will greatly differ for Grimes compared with Tokyo three years ago, her lineup aside. Though always learning from Ledecky and trying to embody her poise and class, Grimes doesn’t need to rely on the four-time Olympian to show her how the Games work.

With experience, Grimes said she’s much more comfortable competing on an international stage, and since Tokyo, she’s implemented a stronger emphasis on post-race recovery. In bed at a reasonable hour is not negotiable, and staying off her feet is a priority.

Trying to mitigate the pressure and nerves, she’s practiced tapping into a calm headspace before competing while blasting Dua Lipa until she goes to the ready room. Part of that mindset is remembering to have fun and the comfort of knowing her family is in the stands cheering, she says. And thinking about how happy she’ll be when she hits the wall. 

"She's learning how to try and absorb all that (pressure), but also take it all in and use it as energy," Aitken added. "So she's trying to find her way through that."

While a pool inside Paris La Défense Arena is new for everyone, Grimes got a preview of the Olympic marathon swimming course last summer. Kind of. 

The Open Water Swimming World Cup was one of multiple Olympic test events canceled in 2023 because of poor water quality – a lingering concern this summer with recent elevated bacteria levels, including E. Coli. Grimes is eager to swim in the iconic river but also understands it’s “dirty water." Despite concerns, she’s hoping for the best. 

Seeing the open water course last summer at least allows her to visualize her 10k Olympic race on Aug. 8. Organizers have alternative race dates and a backup venue in place, should water quality remain dangerous.

A podium spot in open water is "definitely" a goal, she says, especially in a two-hour race where finishing place is more highly regarded compared with times, like in the pool.

"The hard part about doing a few different events is that I want to be the best that I can in all of them," Grimes says. "But I feel like you give up a little bit of that when you try and spread yourself across multiple events. But I can see myself in the future, one day, just focusing on one event."

One day, maybe. But that’s the only thing Grimes isn’t ready for yet.