2025 World Championships Previews: No Question of If for McIntosh in Women’s 400 IM

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
• Psych Sheet (Google Sheet Courtesy of Troyy)
• Psych Sheet (PDF)

By the Numbers – Women’s 400 I.M.

• World Record: 4:23.65 – Summer McIntosh, Canada (2025)
• World Junior Record: 4:24.38 – Summer McIntosh, Canada (2024)
• Championship Record: 4:27.11 – Summer McIntosh, Canada (2023)
• 2023 World Champion: Summer McIntosh (CAN) – 4:27.11
• 2024 Olympic Champion: Summer McIntosh (CAN) – 4:27.71

Returning Olympic Finalists

• Summer McIntosh (1st), Katie Grimes (2nd), Emma Weyant (3rd), Freya Colbert (4th), Mio Narita (6th)

The 2024 Paris Olympics saw the teenage World Record holder, Summer McIntosh, swim her way to her first Olympic Gold Medal, one of three she collected in the City of Lights. The Canadian won the event in 4:27.71, which, while well off her recently minted new WR set at the 2024 Canadian Trials of 4:24.38, was still the 5th fastest performance of all time and 4th fastest of her career.

The preamble to this preview is short, very short, because, well, honestly, I could just copy the text from the 2024 preview and be pretty set. Much of the field is the same, and truthfully, many of the storylines, especially those involving McIntosh, are similar.

In 2023, Summer McIntosh entered the World Champs as the 2022 World Champion, having brought the WR to a new level at Trials, becoming the first swimmer under 4:26. In 2024, Summer McIntosh entered the Olympics as the 2023 World Champion, having brought the WR to a new level at Trials, becoming the first swimmer under 4:25. In 2025, Summer McIntosh enters the World Championships as the 2024 Olympic Champion, having brought the WR to a new level at Trials, becoming the first swimmer under 4:24.

Thankfully, I won’t just Ctrl-c, Ctrl-v, as not only would Braden probably (very likely) disapprove, but also I came up with a clever sub-heading theme, and we all know that’s why I am here. I live for these types of comments:

But enough about me, you’re all here for the 400 IM, and the last time I swam it in LCM was 2011, which was before some of our entrants were born.

“You’re Still The One”

Summer’s dominance in the event is well documented, but it cannot hurt to just go over it a little more. Besides occupying the entirety of the By the Numbers section above, owning the WR, WJR, CR, and being the 2023 Worlds and 2024 Olympic Champion (more on the 2024 Worlds later), she also dominates the all-time performances list.

McIntosh owns the three fastest times ever and six of the top 10. Of the six swimmers who have ever been under 4:30, McIntosh owns 10 of the 18 performances. Only Katinka Hosszu, who holds the one record McIntosh is missing, the Olympic Record, joins the Canadian with more than one sub-4:30 swim, having done so four times.

Among active swimmers, McIntosh is joined only by Kaylee McKeown under the 4:30 barrier, but the Australian star has eschewed the event at international competitions and the next closest competitor, time wise, is the American Katie Grimes, whose PB of 4:31.41 ranks her as the 15th fastest performer ever, but well outside the top 25 performances.

Much like McKeown, McIntosh seems to pull out all the stops at non-World meets. McIntosh’s fastest three performances, as noted above, all came at Canadian Trials, and she was slower at each of the successive meets after.

In comparing her latest WR, which came in the same meet in which she not only rattled both the 200 Fly and 800 Free records but also broke the 400 free and 200 IM records, McIntosh has been making strides in the backstroke and freestyle lengths. The backstroke in particular is noteworthy, as evidenced by her silver medal in the 200 back at the 2024 Budapest Short Course Worlds.

Even before the 2025 Canadian Trials, McIntosh easily would have been the favorite for this event as she casually threw down her now 4th, then 3rd fastest time at a sleepy Westmont Pro Swim Series, where she once again broke the 4:28 barrier as she recorded a mark of 4:26.98.

Leading the world rankings by a staggering 10 seconds, as the article title suggests, it’s not a question of if she wins but rather, by how much. The event’s prelims and finals take place on the last of eight days of competition in Singapore, and McIntosh likely has a busy schedule as she is also entered in the 400/800 free, 200 Fly, and 200 IM, the latter two of which she is also the Olympic champion in. McIntosh also potentially plays a role in all of Canada’s relays, so she could be in for a busier week, as Worlds, despite being a longer meet than Canadian Trials, has semifinals for events 200 meters and less.

Perhaps “That’s the Way It Is” would have been a better sub-heading, as not only is not as exclusionary, but it helps include the other large sub-sect of Canadian culture. 9th on the preliminary entry list is McIntosh’s teammate Mary-Sophie Harvey. Harvey, a two-time World relay medalist, likewise had a strong meet at Canadian trials, setting PBs in the 200 breast and 200 IM as well as in this event, where her 4:35.56 ranks her 6th in the World this year.

Like her compatriot, Harvey has a busy schedule as she is entered in the 200 free (#6), 200 breast (#10), and 200 IM (#5). Also similar to McIntosh, Harvey plays into all of Canada’s relays, as she won the 100 fly and 200 free, and while, like McIntosh, she did not swim the 100 free, she did qualify 2nd in the event at last year’s Trials, behind only the recently withdrawn Penny Oleksiak.

“Wildest Dreams”

Emma Weyant Katie Grimes (photo: Jack Spitser)

However, one must swim the event to win, and while we have no doubts that Summer won’t swim the event, the IMs have in the past been an albatross, often derailing swimmers via DQs. Ella Eastin and Bethany Galant were DQed in this event at the 2017 US Trials. McKeown was DQed in the 200 IM at the 2023 Worlds, and Alex Walsh, who could have be DQed for the same reason in 2023, was DQed in Paris after putting up a time worthy of the bronze medal in the 200.

With McIntosh’s dominance in the event well established, it would likely take a DQ to displace her, as previously mentioned, none of her competitors have broken 4:30, let alone 4:31. But if there were to be a pair looking to join McIntosh under 4:30, the most likely pair would be Katie Grimes and Emma Weyant.

Not only are they the #2 and #3 seeds behind their northern neighbor, but the Team USA teammates have also collected the silver medal at every International Meet, with the exception of the 2024 Worlds. Weyant collected silver at the Tokyo Olympics, and Grimes took silver at the 2022 Worlds, 2023 Worlds, and 2024 Olympics, all of which were one step lower on the podium than McIntosh. These trends would suggest that Grimes would be favored once again to take silver, especially as Weyant took bronze in 2022 and 2024, but this year’s results may say otherwise. Grimes last year at both the US Olympic Trials and Olympics got the edge to be the top American, but this year, Weyant has flipped the script.

After a DQ in this event, derailed her 2023 plans, Weyant bounced back last summer to claim the Olympic Bronze medal in 4:34.93. She continued that momentum into this season with a 2nd place at NCAAs in the event, and before US Trials, blasted a 4:33.95 at the Fort Lauderdale PSS. The performance, her 4th fastest ever and fastest since the Tokyo Olympics, vaulted her up into the #2 spot in the world and made her the favorite at US Trials. While a little slower at Trials, her 4:34.81 was more than enough to punch her ticket to Singapore, where she will be making her first Worlds appearance since 2022.

On the other hand, Grimes, who, like McIntosh, burst onto the international scene as a teen phenom, entered the US Trials with some questions. Despite being the Olympic silver medalist, Grimes, who made the jump to the NCAA mid-season, struggled in 2025, finishing 4th at NCAAs and recording only one LCM time before Trials, finishing 5th in Fort Lauderdale with a time of 4:42.48.

After scratching a few events and missing the team in the 800 free, Grimes safely navigated the finals of the 400 IM, taking 2nd behind Weyant, with a time of 4:37.22. While making the team was the ultimate goal, and the time a little irrelevant, it’s been part of a worrying trend.

While every athlete has ups and downs, for one still in her prime and for one whose club coach said she would not be fully tapered until the Olympics, the downward trend in results is worrying. The training jump to UVA and with Todd Desorbo may have something to do with it, but Grimes will certainly need to be better than 4:37.22 if she looks to medal.

“Let Me Be There”

Freya Constance Colbert (photo: Jack Spitser)

The 2024 World Championships in Doha occurred due to a backlog of hosting commitments caused by the COVID-19 pandemic and the resulting schedule shifts. Although the event was sparsely attended and not all the times were swum by tapered athletes, the results are still noteworthy. In the 400 IM, Great Britain’s Freya Colbert took advantage of the two-time reigning champion’s absence and became the first person to be named World Champion not named McIntosh since 2019.

The result was not too much of a surprise, as Colbert had been making steady improvements over the past few years. She placed 12th in the prelims in 2022 with a time of 4:45.55, but earned bronze later that summer at the European Championships with a time of 4:40.06, (she was 4th at the Commonwealth Games with a time of 4:39.80). After a busy 2022, she finaled the following summer at the 2023 Worlds, placing 5th with a time of 4:35.28.

Just one of two returning finalists in 2024, Colbert claimed gold in a time of 4:37.14. While not a PB, it was her first individual Worlds medal and was a strong performance as she was 4th at breast to free turn. The Brit carried on this momentum into the summer as she posted a new personal best of 4:34.01 at her British Trials and then, while a little slower at the Olympics, was within a second of the medals as she finished 4th in a time of 4:35.67.

This year Colbert looks to be in a strong position to make the World Finals for the 3rd straight year. She was second at British Trials, touching in 4:36.83, but much like in Doha, she used a strong last 100 to close what was a 1.99-second gap to the early leader Abbie Wood to just a deficit of .17 at the finish. Wood, a two-time Olympic finalist in the 200 IM, added the 400 IM recently back into her event order, and it showed as she posted a new PB of 4:36.66. A 2021 Tokyo finalist in the 200 breast, Wood, took the bronze medal at the 2024 Short Course Worlds behind McIntosh and Grimes.

Connected together by a long shared history and by this singer of this sub-heading, Australia also has two swimmers who are looking to make return trips to the finals of the 400 IM. Jenna Forrester, the senior of the two has the faster PB and has the hardware to prove it. Forrester claimed bronze in Fukuoka with a new PB of 4:32.30, a performance that makes her the 16th fastest performer of all time and the 3rd fastest of all the entrants. However, over the past two years, Forrester has struggled to replicate that success and has been surpassed by compatriot Ella Ramsay as Australia’s premier 400 IMer.

Ramsay, as an 18-year-old, missed out on the 2023 Worlds by placing 3rd three times at Australian Trials, but rebounded a year later, winning the 400 IM at the 2024 Olympic Trials in 4:36.56. She continued that success to Paris, qualifying for the final in 6th place (4:39.04) and ultimately placing 5th in the final with a time of 4:38.01, while Forrester missed out on the final, placing 9th in the prelims (4:40.55).

Ramsay got the better of Forrester again at trials this year, winning the 400 IM in a new PB of 4:36.12, with Forrester just behind at 4:36.19. It was a strong performance from Forrester as she had yet to make the team, placing 3rd in the 200 IM and 200 Back earlier in the week, whereas Ramsay had already made the team by virtue of winning the 200 IM and 200 Breast, as well as by placing 2nd in the 100 breast.

Of the four, Colbert is the highest ranked, coming in as the #4 seed with her 4:34.01. The other three are on the outs, looking in with Ramsay coming in as the #10 seed (4:36.12) with Forrester (11th-4:36.19) and Wood (13th-4:36.66) not far behind.

“Whenever, Wherever”

Seeded 5th through 8th, the next four swimmers are all young swimmers, who are all looking to improve their position from last year, or in one case, make a name for themselves on the World Stage.

World Aquatics Championships
Fukuoka (JPN)
14-30 JULY 2023

Ellen Walshe of Ireland, seeded 6th at 4:35.32 and Mio Narita of Japan, seeded just .07 back in 7th, are both looking to make it back into the finals of the event after having done so in Paris. Walshe, the eldest of this group of four at 23, broke 4:40 for the first time last summer, going 4:37.94 in May. She safely navigated the prelims in Paris, going 4:39.97, but struggled a little in the final, placing 8th in 4:40.70. Narita, a former World Junior Record holder in the event, too, was a little off her best in Paris. She entered with a then PB of 4:36.71, was 5th in Prelims with a 4:37.84, but fell one spot in the finals, adding .99 to stop the clock in 4:38.83.

However, the pair has already been off to a strong 2025. Narita started it with a new PB by winning the 2025 Japan National Swimming Championship this past March, recording a new PB of 4:35.39. Walshe claimed 2nd behind Weyant at the Fort Lauderdale PSS, recording a new Irish record of 4:35.32, and followed up that performance with a 4:37.80 win at the Sette Colle last month. Sitting 3rd and 4th in the rankings this season, the Irish and Japanese stars look to be in a good position to make the final, should they replicate their early-season successes.

Seeded 4th and 8th, the other two swimmers in this young and international grouping are a little bit more of a question mark. Continuing a long line of strong IMers for her nation, Hungary’s Vivien Jackl is the 4th seed entering with her time of 4:34.96 from the 2024 Hungarian Trials. That time burst the junior swimmer onto the scene and made her a strong contender to make the final in Paris. A 4:39.28, course record at the 2024 European Juniors in the lead-up to Paris, may have been a sign of training, but the young star in the making failed to make the Olympic final, placing 14th with a time of 4:44.47. This season, she hasn’t approached that sub-4:35 territory, winning Hungarian Trials in 4:40.70 and falling to 3rd at European Juniors earlier this month, recording a time of 4:40.40 and losing her championships record in the process. Just 16, Jackl is also entered in the 800 and 1500 freestyles, and while Walshe and Narita are also entered in other events, neither will be close to the total distance that the Hungarian will be at.

Seeded 8th is the youngest competitor, 12-year-old Yu Zidi. The Chinese star recorded a mark of 4:35.53 in May at the 2025 Chinese National Swimming Championships. The time, a new PB by nearly five seconds, ranks Yu 5th in the world this year. Being so young, not yet even a teenager, there is not much to base things on for how we can expect Yu to perform. As a top 8 seed in the 200 fly (6th) and entered in the 200 IM (16th), the 400 IM will be the last event on her schedule. If she is affected by nerves, as any swimmer can be, she will have other swims before this event to help ease the pressure.

“Wannabe”

All of the swimmers mentioned above and all those not mentioned obviously “want to be” in the final, but with only eight spots up for grabs, there obviously are going to be some disappointments.

Summer McIntosh, like many of these swimmers, has a busy schedule, but of all her events, this event is likely the surest bet for her to win. Whether it’s a World Record is another matter, as not only does this event come on the last day, but as mentioned above, she hasn’t yet recorded a PB in the event at the end-of-season meet.

Behind McIntosh, the American duo seems to be the likeliest contenders for the minor medals, as both Grimes and Weyant have medaled at every Worlds or Olympics they have contested the event in. Of the two, Weyant’s performances this year seem to give her the edge over Grimes, who has been fighting both the high expectations placed upon by bursting onto the scene so young as well as with the recent change in training bases.

If anyone were to break up the American pair, based on time, it would be Jenna Forrester, who took bronze in 2023 with a time of 4:32.30 after qualifying first in the prelims at 4:35.88. However, the Aussie has struggled to get back into that form and failed to make the final in Paris. Based on recent performances, Freya Colbert would appear to take up that mantle, as she finished 4th in Paris and is the reigning World Champion.

Walshe and Narita’s times this season and their appearances in the final last summer make them likely bets to make the final, but by no means are they locks. Jackl and Yu are the big question marks. Jackl has the 4th fastest entry time at 4:34.96, but her performances since then seem to be trending in the other direction. As for the Chinese star, there is no taking away from the fact that she has the 5th fastest performance of the year, but the field is very tight behind her, and while the sky is literally the limit, the experience of Harvey and Ramasy at big meets tips the edge in their favor.

Last year, we predicted the top four in order correctly and had Mio Narita making the Olympic Final. We had Anastasia Gorbenko, who is absent from this event this year, making the final, as well as Forrester and Jackl. While 5 out of 8 isn’t bad, the field this year appears to be a much tighter affair so while the top 8 below is our best prediction, it would not surprise me if Forrester, Yu, Jackl, or Wood make the final. Entering the Olympics, the 8th fastest qualifying time was Weyant’s 4:35.56; this year its Yu Zidi at 4:35.53. While just .03 is negligible, the fact that it’s not just in the same area, but faster, shows that this event is going to be a fight to make the final.

And that’s exactly what this event needs. While McIntosh has been blazing a path in the event each year, behind her, the field has been rather stagnant. Only one other active swimmer has a PB within five seconds of her, and that’s Kaylee McKeown, who doesn’t race this event often. Of the competitors, McIntosh is nearly 10 seconds faster than Grimes’s PB. But with the youth like Narita, Yu, and Jackl as well as the return to form of Weyant, this event may be faster than it has been over the past five years.

SwimSwam’s Picks

Dark Horse: Sara Franceschi (ITA) – As mentioned above, the field is tight, and outside of McIntosh, the remaining group will need to be near their best if they hope to advance to the final. Italy’s Sara Franceschi could play spoiler to those above, if she recaptures the form that brought her to bronze in Doha. After placing 9th in the Olympics in Tokyo, she did not contest the event at the 2022 Worlds, instead placing 4th at the European Championships. Her 4:37.73 in Fukuoka was good for 6th, but she made the trip in early 2024 to Doha, claiming bronze in 4:37.86. However, she placed just 15th out of 16 competitors in Paris, with a 4:48.89, and her recent results have been in a similar vein: placing 4th in 4:45.44 at Italian Nationals in April and taking 4th at Sette Colli in 4:45.00.