20-Yr-Old Roos Vanotterdijk Rips 55.84 100 Fly Belgian Record

2025 World Championships

• July 27 – August 3, 2025 (pool swimming)
• Singapore, Singapore
• World Aquatics Championships Arena
• LCM (50m)
• Meet Central
• How To Watch
• SwimSwam Preview Index
• Entry Book
• Live Results
• Live Recaps
  • Prelims: Day 1
  • Finals: Day 1

The final of the women’s 100m butterfly featured American world record holder Gretchen Walsh and the 22-year-old didn’t disappoint, capturing gold in a magnificent time of 54.73, a new World Championships record.

However, snagging the silver was 20-year-old Roos Vanotterdijk, with the Belgian entering entirely new territory with her first-ever sub-56-second time of 55.84. That overtook her newly minted national record of 56.07 notched during last night’s semi-final.

Tonight, Vanotterdijk opened in 25.68 and closed in 30.16 to register the fastest time of her career.

Entering this competition, Vanotterdijk’s national record stood at the 57.05 established at this year’s Swim Open Stockholm in April. That means in a matter of months, the ace has slashed over a second off her best-ever 100m fly outing.

The Belgian’s 55.84 national record now checks her in as the 8th-fastest performer of all time.

Top 10 Women’s LCM 100 Butterfly Performers All-Time

1. Gretchen Walsh (USA) – 54.60, 2025
2. Sarah Sjostrom (SWE) – 55.48, 2016
3. Torri Huske (USA) – 55.52, 2024
4. Maggie MacNeil (CAN) – 55.59, 2021
5. Zhang Yufei (CHN) – 55.62, 2020 & Regan Smith (USA) – 55.62, 2024
6. –
7. Emma McKeon (AUS) – 55.72, 2021
8. Roos Vanotterdijk (BEL) – 55.84, 2025
9. Dana Vollmer (USA) – 55.98, 2012
10. Liu Zige (CHN) – 56.07, 2009

But this trajectory is just par for the course for Vanotterdijk who trained under Fred Vergnoux when he was head of the Royal Belgian Swimming Federation before she moved under Mark Faber. Faber replaced Vergnoux in November of last year.

She owns the Belgian national records across the long course 100m free (53.62), 50m back (27.81), 100m back (58.97), 50m fly (25.63), 100m fly (55.84), 200m IM (2:09.73).

Remarkably, all of these new standards have been established in the first half of this year, with the most recent record in the 200m IM set just at last month’s U23 Championships.

Vanotterdijk carries the most entries of all swimmers at these World Championships, slated to race an incredible seven individual races.

WOMEN’S 100 BUTTERFLY – Final

• World Record: 54.60– Gretchen Walsh, United States (2025)
• World Junior Record: 56.33– Mizuki Hirai, Japan (2024)
• Championship Record: 55.53 – Sarah Sjostrom, Sweden (2017)
• 2023 World Champion – Zhang Yufei, China — 56.12
• 2024 Olympic Champion – Torri Huske, United States — 55.59

Final: 

1. Gretchen Walsh (United States) — 54.73 *Championship Record*
2. Roos Vanotterdijk (Belgium) — 55.84
3. Alexandria Perkins (Australia) — 56.33
4. Zhang Yufei (China) — 56.47
5. Daria Klepikova (NAB) — 56.53
6. Angelina Köhler (Germany) — 56.57
7. Mizuki Hirai (Japan) — 56.83
8. Yu Yiting (China) — 57.36