There was an emphatic slap of the water, the splash shooting right up into her be-goggled face. There was a victory roar unlike anything she had unleashed all week. There was a giant, unabashed smile as she made her way out of the Kazan Arena pool. And minutes later, on the medal stand, there was a beaming, full-throated sing-along to “The Star-Spangled Banner” as it played for the fifth time here in her honor.

This time felt different for Katie Ledecky. The sense of accomplishment was complete. On Saturday night, in her final race of the FINA World Championships, she made plenty more history — a world record in the women’s 800-meter freestyle, with a once-unfathomable time of 8 minutes 7.39 seconds — and wrapped up one of the great single-meet performances in swimming history. When it was over, for the first time all week, she exhaled.

“I had just finished my meet and . . . I knew it was a real special night for our team, so I was just going to enjoy it,” said Ledecky, an 18-year-old Bethesda native. “It was my last time up on the medal stand, and to see everybody in the crowd — it’s really a neat thing.”

Across seven remarkable days here, she set three world records, won five gold medals, expanded her repertoire of world-class events and invented a new achievement — the Ledecky Slam, an unprecedented sweep of the 200, 400, 800 and 1,500 freestyles — that may never be duplicated — unless by Ledecky herself at the next world championships two years from now. She would probably do it at the 2016 Rio De Janeiro Olympics as well, but the 1,500 is not contested in the Olympics.

For every swimmer chasing world-class dreams, there is a perfect race somewhere out there, and you never quite achieve it because there is always something that can be improved, a hundredth of a second that can be shaved. But for Ledecky, whose sheer ability means she can take aim at things no one else in the world would even fathom, this race came perhaps as close as any in her career to perfect.

Katie Ledecky broke her own world record in the womens' 1500-meter freestyle at the world swimming championships in Kazan, Russia. Thirty minutes later, she was back in the pool again to qualify for the 200 meter freestyle final. (Jayne W. Orenstein/The Washington Post)

“I just couldn’t be happier with how that swim went or how this whole week went. It felt pretty good,” she said. “It got a little tough around the 550 [mark], but I knew I could finish hard. I sort of backed off that first 75 [meters]. That’s what Bruce [Gemmell, her coach,] wanted me to do. He told me to put that into my last 75. I knew I could finish hard because I had done what I needed to do the first 100. I’m just very happy with how that swim went.”

Asked whether this was the best swim of his sister’s life, brother Michael Ledecky, a rising senior at Harvard and a walking record book of Katie’s swimming career, offered a one-word response: “Undoubtedly.”

Gemmell, the coach who has driven Ledecky these past three years to places no female swimmer has ever gone, would have no such talk of perfection or “best ever.” In his mind, perfection doesn’t exist and “best ever” is temporary.

“I don’t know if it was close to a perfect race,” he said. “Given the circumstances, especially at the end of a long week, I think you have to give it a little special boost on the how-good-it-was meter. [But] we have ways we can get better. Her turns are still not particularly good, and we’ve already set up some time [back home] to work on those. But tonight her last turn was particularly good.”

That last turn, at the 750-meter mark, found Ledecky bearing down at full-throttle. Her powerful kick, completely absent from some of her earlier races — even her two world record swims in the preliminaries and finals of the 1,500, as she conserved energy — was fully engaged. She turned at 750 and headed for the home, with a sold-out crowd coming to its feet, and made it to the wall with a 28.41 split for that lap — her fastest of the entire meet, other than leadoff laps when she had a diving start.

Think about that for a moment. After 6,150 meters of racing this week, including four 200-meter sprints, Ledecky’s final 50 meters — in a distance race she wound up winning by more than 10 seconds, her closest pursuer, New Zealand’s Lauren Boyle, some half a pool behind her — produced her fastest lap of the meet.

“There was something special for her, when she knows it’s her last race of a long week — the last race of a long summer,” Gemmell said. “So she doesn’t have to worry or think about it or manage any energy going forward.”

A small part of Ledecky — but only a small part — was disappointed she hadn’t gone a second slower. Saturday — 8/8 on the calendar — would have been her late grandfather Jaromir’s 88th birthday, and during a visit with her family Friday, they all agreed an 8:08-point-something would have been eerily fitting. Alas, on her final lap of her final swim of her final meet of the summer, she couldn’t rein herself in.

“I didn’t really have any pressure,” she said. “I didn’t really feel I needed to do that. That’s why was really happy with 8:07.”

Even though she already is generally regarded as the world’s top female swimmer, this week somehow managed to elevate the legacy she has been building since winning gold in the 800 at the 2012 London Olympics. The week cemented Ledecky’s status as the best female distance swimmer since Janet Evans, and she likely would supplant Evans in most minds, if she hasn’t already, with a representative showing at Rio.

“It just seems like, when it comes to a big event, all of a sudden a world record is going down,” said Frank Busch, USA Swimming’s national team director. “It’s Katie versus Katie.”

Increasingly, the only relevant comparisons for Ledecky are swimmers of the opposite gender. Her feats recall those of icons such as Tim Shaw, who won the 200, 400 and 1,500 free at the 1975 world championships (there was no men’s 800 at the time); Ian Thorpe, the last swimmer to hold world records at three different freestyle distances; and even Michael Phelps, whose five individual golds (plus three relay golds) at the 2008 Beijing Olympics are considered the top individual performance in the sport’s history.

It did not escape notice Saturday morning, following preliminary heats for the men’s 1,500 free, that Ledecky’s time of 15:27.71 in the women’s qualifying five days earlier — a world record she wasn’t really trying to set — would have ranked her 28th of the 45 men attempting to qualify for the finals.

“I’m totally blown away by Katie Ledecky, 100 percent,” said Connor Jaeger, an American who finished second in men’s 1,500 qualifying Saturday. “I don’t know if I tell her that enough. I’m really impressed by her and motivated by her and kind of look up to her as a competitor, just her fearlessness going into heats and finals.”

As she left the interview area Saturday night, Ledecky was swarmed by a group of Russian volunteer assistants, who are assigned to help swimmers navigate the pool areas and to carry their belongings from stop to stop. They looked young, perhaps college age, but that would make them older than Ledecky, who just graduated high school and doesn’t even own a driver’s license.

They wanted their photos taken with swimming’s newest superstar, and Ledecky obliged, flashing her toothy smile for all. When they were done, she patted several of them on the back and said, “Thanks for all the work you did this week.”

Ahead for Ledecky is a rare day to be a spectator as the meet comes to an end Sunday, a long flight home and — next week — an appointment to have her wisdom teeth removed. At least it buys her a break from practice.

But the break won’t be long, and when Ledecky gets back in the water, it will officially be Year 4 of a swimmer’s internal quadrennial calendar — an Olympic year. There is work still to be done. That turn still needs some work.

“You never know what [your competitors are] going to do,” she said. “Look how I came along in 2012. I know there’s always someone out there working hard, and there’s a 15-year-old that’s gunning for me next year. That’s what pushes me every day in practice.”