How Many Individual World Records are in Danger of Falling at World Championships?

2025 World Championships

• July 27 – August 3, 2025 (pool swimming)
• Singapore, Singapore
• World Aquatics Championships Arena
• LCM (50m)
• Meet Central
• Live Results
• SwimSwam Preview Index

The first swimming session of the World Aquatics Championships is less than a week out, and some of the fastest swims in history are living on borrowed time.

Only two individual world records were broken last summer in Paris, with China’s Pan Zhanle’s heroic 100 free in 46.40, and Bobby Finke tearing down the house and the world mark in the 1500 free in 14:30.67. The World Championships have the potential to be home to even more historic performances.

With rising talents and established veterans, here are some all-time standards (not a comprehensive list, and in no particular order) that could fall in Singapore.

Women’s 800 Freestyle

• World Record: Katie Ledecky (USA) – 8:04.12 (2025)

The showdown between Katie Ledecky and Summer McIntosh in the 800 freestyle is one of the most anticipated races in Singapore. It’s a clash between the greatest female distance swimmer in history and one of the sport’s most dynamic rising stars.

Ledecky broke her own world record earlier this year in Fort Lauderdale, lowering her legendary time from 8:04.79 at the 2016 Rio Olympics to the current world standard of 8:04.12. Meanwhile, McIntosh has rapidly closed the gap, dropping from 8:11.39 in early 2024 to 8:05.07 at Canadian Trials, just under a second behind Ledecky’s mark.

While Ledecky remains undefeated in the 800 free on the global stage, McIntosh did hand her a rare loss at a sectional meet in early 2024. Both enter Worlds in peak form, and with less than a second between them, another record-breaking swim could be on the horizon, possibly from both.

Men’s 200 IM

• World Record: Ryan Lochte (USA) – 1:54.00 (2011)

After recently announcing that he will be dropping the 200 fly and 200 breast in Singapore, Leon Marchand’s focus will be on both the 200 and 400 IMs. Marchand will be looking to become the first man under 1:54 in the history of the event.

Marchand, the reigning Olympic gold medalist from Paris in this event, strategically dropped the 200 fly and 200 breast in pursuit of that 200 IM all-time mark that has eluded the world, including Michael Phelps, since 2011.

Marchand enters just six one-hundredths off of Lochte’s mark in the 200 IM. With no other races on the schedule for Marchand on the day, this race allows him the opportunity to reach never-before-seen levels in the event.

It is relevant to mention that Marchand suffered a stress fracture, resulting in a cracked rib earlier this season, which kept him out of the water for a week. While dropping the fly and breast may help him in unleashing some monster swims, his previous injuries may hinder him from being in his best condition.

Women’s 100 Butterfly

• World Record: Gretchen Walsh (USA) – 54.60 (2025)

Gretchen Walsh enters Singapore as a heavy favorite in the women’s 100 butterfly, holding the seven fastest swims in history, all set within the past 13 months. She first broke Sarah Sjöström’s 2016 world record (55.58) at U.S. Trials in 55.18, then became the first woman ever under 55 seconds, clocking 54.60 in May and 54.76 in June.

In Fort Lauderdale, she dominated the field en route to setting the current all-time standard by nearly two seconds despite having the third-slowest reaction time in the final. With her unmatched speed and consistency in the event, Walsh may only need a clean start to lower the world record again.

The question for Walsh likely won’t be if she will win gold, but how low she can go.

Women’s 400 Freestyle & 400 IM 

• 400 Freestyle World Record: Summer McIntosh (CAN) – 3:54.18 (2025)
• 400 IM World Record: Summer McIntosh (CAN) – 4:23.65 (2025)

McIntosh enters the 400 freestyle and 400 IM holding the top seed in each. She has added from her best time in the 400+ races at the two last big international meets (2023 Worlds, 2024 Olympics), but with a new coach this year in Fred Vergnoux, who has significant experience with distance-heavy lineups for swimmers (Mireia Belmonte for example), we could be in for some record times in these events.

In the 400 free, McIntosh holds a clear edge over Ledecky, holding the world record at 3:54.18, more than two seconds ahead of Ledecky’s entered time of 3:56.81. This will be their first head-to-head swim for gold in Singapore.

McIntosh is the only woman ever under 3:55 and just one of two to break 3:56, alongside Ariarne Titmus, who won’t be racing in Singapore. The world record has changed hands four times between Titmus and McIntosh since 2022, with McIntosh reclaiming it at Canadian Trials.

With both stars in peak form, the two will inevitably push one another for the entirety of the race.

In the 400 IM, McIntosh comes in as the clear favorite, holding the top seed by nearly 10 seconds. At just 18, she’s already broken the world record three times, each at Canadian Trials in 2023, 2024, and 2025, becoming the only woman in history to swim under 4:26, 4:25, and 4:24.

Her current world record of 4:23.65 sits more than four seconds ahead of her gold-medal time from the Paris Olympics, where she won in 4:27.71. With elite range across all strokes and distances, McIntosh has continued to redefine what’s possible in this race.

Much like Gretchen Walsh in the 100 fly, the conversation isn’t just about whether McIntosh will win, but how fast she can potentially lower the world standard.

Of these two events, with the 400 free being early in her schedule, that world record may be more of a possibility. Having the 400 IM to close out her week in Singapore, after the 800 free no less, may be a bit more of a challenge.

Men’s 1500 Freestyle

• World Record: Bobby Finke (USA) – 14:30.67 (2024)

One of two world records broken last summer in Paris, Bobby Finke returns to the 1500 freestyle in Singapore, aiming to better his own all-time mark and win gold in the process.

The American distance star won’t be alone in that pursuit. Ireland’s Daniel Wiffen and Germany’s Florian Wellbrock, already a four-time gold medalist in open water at these championships, are also serious contenders for both gold and the world record. The event will be notably without Italy’s Gregorio Paltrinieri, who withdrew from pool events after injuring his finger during the open water portion of these World Championships.

With several of the top distance swimmers in peak form, the longest event of the meet for the men could deliver another historic finish.

Women’s 50/100 Backstroke

• 50 Backstroke World Record: Kaylee McKeown (AUS) – 26.86 (2023)
• 100 Backstroke World Record: Regan Smith (USA) – 57.13 (2024)

Regan Smith and Kaylee McKeown will clash once again in the 100 backstroke, continuing one of the sport’s most intense rivalries. McKeown took Olympic gold last summer in 57.33, but Smith’s world record from U.S. Trials still stands.

Both McKeown and Smith have had very interesting years up to this point. McKeown took an extended break following the World Cup, while Smith has been training at Arizona State and Texas all year, ultimately settling in Austin after the NCAA Championships. Smith also took a month off post-Paris and some time off after the World Cup.

Without the pressure of the Olympic year and the time off for both, will it lower the pressure and create a really fast time, or will it result in the opposite?

The two have traded the world mark since 2019, with McKeown first breaking Smith’s record in 2021, then lowering it again in 2023. With the title and world record potentially on the line, expect another tight finish between two of the fastest backstrokers in history.

The women’s 50 back will be headlined by McKeown and Katharine Berkoff. Top-seeded Berkoff comes in with an entry time of 26.97, 11 one-hundredths off the all-time standard of McKeown from 2023.

Berkoff is the only swimmer in the World this year to be under 27 seconds in the event; she is also one of only two swimmers in the field who have been under the 27-second barrier in history.

Less than a quarter of a second separates the top five entries; Canada’s Kylie Masse (3rd seed with 27.13) and Smith (5th seed with 27.20) are comfortably positioned in the mix for the podium.

For Smith, she will face the tough double with the 200 fly and 50 back. But her best time of 27.10 from Fukuoka still slots her in as the 5th fastest performer in history.

China’s Letian Wan (27.09) and Great Britain’s Lauren Cox (27.15) are also in the hunt.

Men’s 100 Backstroke

• World Record: Thomas Ceccon (ITA) – 51.60 (2022)

The men’s 100 backstroke is the tightest field in Singapore, with just 0.24 seconds separating the top seven seeds. World record holder Thomas Ceccon leads at 52.00, followed closely by Xu Jiayu (52.02) and Kliment Kolesnikov (52.04), three of the four fastest performers in history.

Ceccon beat Jiayu for gold last summer in Paris, and the depth behind them is just as strong. Olympic 200 back champ Hubert Kos (52.24) and Apostolos Christou (52.23) are also in the mix. With this much speed, multiple sub-52 swims in the final isn’t out of the question.

​​Kolesnikov’s teammate, world junior record holder Miron Lifintsev, also deserves mention. The 19-year-old posted 52.08 at the Russian Cup in July 2024 and followed with a nearly identical 52.15 at the Russian Trials this April. Coming off a strong Short Course World Championships where he claimed five gold medals—including a sweep of the 50 and 100 back—he’s proven he can rise for the big occasions.

Another noteworthy entry is Peter Coetze, who blasted a 51.99 at the World University Games this week in Berlin, breaking his own WUGs mark of 52.18. This time makes him the top performer in the world this year. Coetze will be competing in Singapore, despite swimming in Berlin this week.

Men’s 400 Freestyle

• World Record: Lukas Maertens (GER) – 3:39.96 (2025)

In April, Germany’s Lukas Maertens broke Paul Biedermann’s 2009 world record in the 400 freestyle, lowering the mark from 3:40.07 to 3:39.96. Now holding the all-time standard, Martens heads into the World Championships as the top seed and clear favorite.

He owns three of the ten fastest performances in history, but the field is stacked. Australia’s Sam Short, the 5th-fastest performer ever, is seeded 2nd, with countryman Elijah Winnington close behind in 3rd. Taking down Martens may require a world record in the process.

Women’s 200 Butterfly (…and 200 IM)

• World Record: Liu Zige (CHN) – 2:01.81 (2009)

McIntosh once again enters World Record watch, this time looking to take down what is widely considered to be one of the toughest world records to crack, Liu Zige’s 200 fly from 2009.

McIntosh has progressively gotten better in this event year over year, from Trials to the major international meet. At the 2023 Canadian Trials, McIntosh would post a time of 2:04.33, following that performance up in Fukuoka, with a gold medal-winning 2:04.06.

The following year, her Canadian Trials 2:04.33 time would be bested in Paris when she swam to an Olympic record 2:03.03.

This season, her 2:02.26 from the 2025 Canadian Trials is the 2nd fastest in history.

If McIntosh wants to take down the longest-standing individual women’s world record, she will need to drop .45 seconds to match the time set by Liu.

McIntosh could also reset her own 200 IM mark, but we wanted to focus more on the legendary butterfly mark in regard to a 200m record.

Women’s 1500 Freestyle 

• World Record: Katie Ledecky (USA) – 15:20.48 (2018)

Ledecky will have the 1500 free sandwiched between her matchups with McIntosh, allowing her to make more history without her Canadian counterpart in the pool.

In Fort Lauderdale earlier this summer, Ledecky blasted the 2nd-fastest time in the event when she finished in 15:24.51, just over four seconds off of her all-time best. Now she will be inserted into this race, having never lost on the world stage, in hopes of topping her 9-year-old mark.

Along with her success in the 800 free this summer, swimming this event before could bode well for her confidence heading into the eventual clash with McIntosh in the 800 free later in the meet.

Men’s 50 Freestyle

• World Record: Cesar Cielo (BRA) — 20.91 (2009)

Australia’s Cameron McEvoy logged 21.06 to win the 2023 world title, and while he’s only been 21.30 so far this year, a perfect swim could take down Cielo’s legendary mark.

McEvoy, who recently became a father, has been focusing on improving his first 15 meters off the start. He’s raced several 25-meter short course events in the past month as part of this training approach. Combined with his tapered speed, this technical work could produce something special in the water.

At the very least, Caeleb Dressel’s textile record of 21.04 is on watch.