American athletes erupted on the first day of the 2024 World Aquatics Swimming Championships (25-meter), breaking five World Records, two American records, and two Championship records. Gretchen Walsh (Nashville, Tenn./University of Virginia) opened the meet by breaking a World Record in the women’s 50m butterfly prelim. During this evening’s semifinal in the same event, she broke the 24-second barrier and earned another World Record by going 23.94.

In the next women’s event, Kate Douglass (Pelham, N.Y./University of Virginia) secured her own World Record, winning the 200m individual medley by more than a second. Her teammate, Alex Walsh (Nashville, Tenn./University of Virginia), earned silver to give the Americans their first 1-2 finish of the meet. Immediately after and leading the race in its entirety, Shaine Casas (McAllen, Texas/Longhorn Aquatics) went 1:49.51 in the men’s 200m individual medley to establish new American and Championship records.

In the final races of the evening, the Americans dominated both the women’s and men’s 4x100m freestyle relay, securing new World Records in both. The women’s team, which included Douglass, Katharine Berkoff (Missoula, Mont./Wolfpack Elite), Alex Shackell (Carmel, Ind./Carmel Swim Club), and G. Walsh, went 3:25.01 to capture Douglass’s second World Record and G. Walsh’s third World Record of the day. Closing out the session, Jack Alexy (Mendham, N.J./University of California – Berkley) clocked 45.05 in the lead off position of the men’s relay to break the American and Championship records. Together as a group, Alexy, Luke Hobson (Reno, Nev./University of Texas), Kieran Smith (Ridgefield, Conn./Gator Swim Club), and Chris Guiliano (Douglassville, Pa./University of Notre Dame) bested their competitors by over two seconds to capture gold and a World Record. The full medal table is available here.

Women’s 400m Freestyle – FINAL

4 – Paige Madden (Mobile, Ala./Sun Devil Swimming), 3:55.12

5 – Claire Weinstein (White Plains, N.Y./Sandpipers of Nevada), 3:56.12

Women’s 50m Butterfly – Semifinal

1 – Gretchen Walsh (Nashville, Tenn./University of Virginia), 23.94*

*World Record

Walsh on breaking her second World Record of the day: “I feel great…I love setting new goals for myself that are based on barriers that I can break, so coming under the 24 (second) mark was insane. Honestly, I’m hoping I can go faster tomorrow and keep this streak going, which would be crazy, but I’m looking forward to it.”

Walsh on her prelims World Record swim: “It was definitely an awesome way to start the meet, the best way I could have. I think I have a lot more to come in that race, just some details I can tune up and execute better. I’m looking forward to semis and finals, and hopefully getting better and better. I’m definitely excited for tonight...It’s going to be a very busy meet, but I’m looking forward to more swims like that hopefully.”

Men’s 50m Butterfly – Semifinal

12– Dare Rose (Jersey City, N.J./California Aquatics), 22.25

Women’s 200m Individual Medley– FINAL

GOLD – Kate Douglass (Pelham, N.Y./University of Virginia), 2:01.63*

SILVER – Alex Walsh (Nashville, Tenn./University of Virginia), 2:02.65

*World Record

Men’s 200m Individual Medley– FINAL

GOLD – Shaine Casas (McAllen, Texas/Longhorn Aquatics), 1:49.51*

4 – Carson Foster (Cincinnati, Ohio/Longhorn Aquatics), 1:51.32

*American record and Championship record

Casas on his American record: “It’s been something I’ve been working towards for a while. For the longest time, I didn’t know if that swim was going to come back, that’s just the ups and downs I’ve been through. I trust in the program and trust in myself. I’ve grown a lot, a tremendous amount, since my first short course Worlds, through long course (Worlds), another long course (Worlds), and the Olympics. I’m a completely different swimmer and human being, I’m pretty proud myself for that. This is the first swim of the (2028 LA) quad, so I’m not going to dwell on it too much, but it’s a great starting point.”

Women’s 100m Backstroke – Semifinal

1 – Regan Smith (Lakeville, Minn./Longhorn Aquatics), 55.05

2 – Katharine Berkoff (Missoula, Mont./Wolfpack Elite), 55.37

Men’s 100m Backstroke – Semifinal

13 – Jack Aikins (Atlanta, Ga./University of Virginia), 50.46

Men’s 1500m Freestyle – FINAL

11 – Daniel Matheson (Peoria, Ariz./Arizona State University), 14:37.56

13 – Charlie Clark (Sandusky, Ohio/Ohio State University), 14:41.61

Women’s 4x100m Freestyle Relay – FINAL

GOLD – USA, 3:25.01*

Kate Douglass (Pelham, N.Y./University of Virginia)

Katharine Berkoff (Missoula, Mont./Wolfpack Elite)

Alex Shackell (Carmel, Ind./Carmel Swim Club)

Gretchen Walsh (Nashville, Tenn./University of Virginia)

*World Record

Douglass on her World Records: “It was really exciting. It was pretty easy to build on the momentum of the night, a lot of World Records were set. To be able to finish it off with a World Record is awesome. My world record in the (200 Individual Medley) was awesome but to break one with this group of girls is even more special, it was a lot more fun.”

Shackell on swimming the relay: “It was pretty cool. That was the first World Record I have been a part of, so that’s a dream come true. I feel like this is building off of this summer and things are going really well. I’m really excited for more relays.”

Men’s 4x100m Freestyle Relay – FINAL

GOLD – USA, 3:01.66*

Jack Alexy (Mendham, N.J./University of California – Berkley) **

Luke Hobson (Reno, Nev./University of Texas)

Kieran Smith (Ridgefield, Conn./Gator Swim Club)

Chris Guiliano (Douglassville, Pa./University of Notre Dame)

*World Record

**American record and Championship record (lead off split)

Alexy on his American and Championship record split: “It was pretty amazing, even more amazing with the USA flag on my cap. I’m just really fortunate to be here representing my country.”

Hobson on his teammates: “It’s so special to get a World Record and win a World Championship with these guys. I couldn’t be happier about it.”

Smith on the relay: “It was super fun; I love that relay. I love starting off with a bang on day one.”

Guiliano on anchoring the relay: “When coach told me I would be anchoring, I always love being in that position. I just wanted to bring it home.”

Men’s 50m Butterfly – Prelim

20– Michael Andrew (Encinitas, Calif./MA Swim Academy), 22.65

Competition continues through Sunday, December 15. Tomorrow’s action includes the women’s and men’s 100m backstroke final, 100m freestyle semifinal, 100m breaststroke semifinal, 50m butterfly final, women’s 800m freestyle final, and the mixed 4x50m medley relay. Meet information and the complete competition schedule are available here.