2025 US Open Swimming Championships: Summer McIntosh swims the second-fastest 400-meter freestyle in history as Leon Marchand returns to winning ways

Was it a fish? Was it a shark? No, that was it Summer McIntosh swimming the second fastest 400 meter freestyle in history with a time of 3:55.37!

Old pop culture references aside, you can hardly blame the confused spectators at the Joe Jamail Texas Swimming Center on Thursday (December 4), as the Canadian superstar left every other finalist at the 2025 US Open Championships in her wake.

While the time wasn’t fast enough to beat her own world record of 3:54.18, it did put to rest any concerns about the three-time Olympic champion’s fitness or health following her withdrawal from the Short Course World Championships in October.

She hit the wall more than 15 seconds ahead of second place Anna Peplowski (4:10.55) and produced a statement with few equals in her first meet since joining coach Bob Bowman‘s training group earlier this year.

“Overall, I’m pretty happy with that,” McIntosh told broadcasters. “This was my first race back of the season, and my first race under Bob [Bowman]so I was pretty excited for it.

“That’s definitely by far the fastest I’ve done this season, so I’m excited [to see] what I can do in the coming months.”

There was even more reason to celebrate within Bowman’s training group, as a four-time Olympic champion Leon Marchand held back the teenage sensation Luka Mijatovic in the men’s 400 meter freestyle, clocking 3:44.70 and the North American 3:45.30.

The swimming marked a return to form for the French superstar, who had shown signs of fragility in his favorite events at the Short Course World Championships.

Team USA Kate Douglass also made headlines by scoring wins in both the women’s 50m freestyle (24.20) and 200m individual medley (2:07.85), while Shaine Casas (24.53) barely managed to fend off Australian teenager Henry Elmore Allan (24.65) in the men’s 50 meter backstroke.

Hungary Hubertus Kos confirmed his control of the men’s 200 meters individual medley in the absence of Olympic champion Marchand, as Katharine Berkoff gave the home crowd more reasons to cheer on the women’s 50 meter backstroke.

There’s even more action planned for day three of the US Open Championships on Friday (December 5), including the 100m butterfly, 100m backstroke, 100m breaststroke, 200m freestyle and the 400m individual medley.