NANTERRE, France — As Katie Ledecky did what Katie Ledecky does, churning back and forth, lap after lap, building her lead quickly to that magical moment when it’s clear she cannot be beaten, a sense of calm came over her. 

She knew she was going to be in the water for a very long time, 15 1/2 minutes as it turned out, swimming one of her two specialities, the 1,500-meter freestyle. She was moving quickly, of course, but this was going to last a while, and why not?  

There was no need to rush history.

When she touched the wall and slapped the water, an uncharacteristic moment of exuberance for the self-effacing superstar, Ledecky had won by more than 10 seconds, one-third of the length of the pool. Her time was her eighth fastest ever, 15 minutes 30.02 seconds, an Olympic record. She now has the 20 fastest times ever swum in the 1,500, an event she hasn’t lost since she was a young student swimming in a regional meet near her home in the Maryland suburbs of Washington, D.C., 14 years ago.

It was another one of those Ledecky moments where she’s in the finishing photo with none of her competitors in sight. But it also was so much more. For the fourth consecutive Olympics, Ledecky has won a gold medal, a remarkable combination of dominance and longevity. With the victory, she won her eighth Olympic gold medal, tying her with swimmer Jenny Thompson for the most gold medals won by an American woman in any Olympic sport, ever. And she has two more opportunities to add to her gold medal total here and pass Thompson, in the 4 x 200 freestyle relay and the 800 meters, an event she has won three times in the Olympics.

The magnitude of the moment was not lost on Ledecky. 

“Each one means a lot,” she said of the eight golds, the first of which was won 12 years ago when she was a little-known 15-year-old at the London Games. “Each one is challenging in its own way. I try not to really dwell on history or the magnitude of things. I’ll just let you guys (journalists) do that.”

And we will. This sport (or any sport, actually) has never seen anyone quite like Ledecky, whose range runs from the 200-meter sprint to the 1,500-meter marathon. And she’s not done yet. No matter how she ends these Olympics — likely with two more medals for a grand total of four this week — she has said numerous times that she intends to keep competing and go for the 2028 Los Angeles Olympics, when she will be 31.

For Ledecky, the longest race in the pool is not only a grueling physical test but also a fascinating mental challenge. She said she uses various “tricks” to stay calm as her mind wanders through the long minutes in the water, but she has also had to battle some unusual doubts over the past few days. 

She wasn’t particularly pleased with her bronze-medal-winning time in the 400 freestyle Saturday, nor with her qualifying times in the prelims for the 400 and on Tuesday for the 1,500.

“I just was kind of feeling like those first three swims, each one of them felt faster than the time,” she said. “And I think doubts enter your mind, you just try to stay positive through it all.”

She said it has been that way all year for her in training at the University of Florida, where she practices with some of the world’s best male distance swimmers under the tutelage of coach Anthony Nesty, a 1988 Olympic gold medalist himself.

“Coach Nesty and all my coaches do a really good job keeping me steady, keeping me on track, reminding me to trust the process,” she said. “I felt like I finally put together a swim (in the 1,500) that matched how I felt and was in line with what I felt I was capable of, just finally having a swim, a time, that I could feel pretty happy with.”

As she was racing Wednesday night, she said she kept her thoughts “very simple” to stay calm. “The voice in my head has been consistent over the years in its tone and its positivity that I try to have in these final races. Just a very positive good voice today that definitely helped me along.”

What did she think of during all that time with her head in the water?

“My mind wandered a lot,” she said. "I was thinking a lot about my teammates back home that I train with everyday. Three years ago in Tokyo, I was repeating my grandmothers’ names in my head a lot. Today I kind of settled on the boys’ names, the boys at Florida that I train with every day. Just thinking of all the practices we’ve done and all the confidence I get from training, being next to them and racing them. That’s the energy I wanted to channel into this race.”

But 15 1/2 minutes requires a lot of thoughts.

“Mentally I was using all the tricks that I’ve used through all these years of distance swimming,” she said. “I have a lot of tricks in my back pocket, counting down all the number of 50s left, thinking about people in my life, my teammates, my family, my friends, so many different things that are going through your head.”

But then all that thinking stopped and the celebrating began. She touched the wall, saw the excellent time, pounded the water and took it all in as the crowd roared for the greatest female swimmer of all time.

“I expected it of myself,” she said later. “It’s not easy to always follow through and get the job done. There are moments of doubt, there are hard days in training where you doubt yourself and you just have to push through and trust in your training and trust that everything will come together in the end, and I’m happy that it did today.”