As well, she was the youngest winner since Tracy Caulkins in 1978.
McIntosh called the results "a dream come true", and praised Grimes, noting "she is around my age and she's a really tough competitor. So I'm looking forward to racing her and keep pushing myself."
2006
Summer McIntosh (born August 18, 2006) is a Canadian competitive swimmer.
A four-time World Aquatics champion and two-time Commonwealth Games gold medalist, she is the current world record holder in the women's 400 metre individual medley.
2011
She was the first 15-year-old to win a World title since China's Ye Shiwen in 2011, and the youngest Canadian world champion in history, surpassing 18-year-old Victor Davis in 1982.
Later in that same session she participated in the event final of the 4 × 200 metre freestyle relay, breaking another junior world record with a 1:54.79 opening leg, the second-fastest of any woman in the event behind Katie Ledecky of the United States.
The Canadian team won the bronze medal.
In her final event, the 400 metre individual medley, McIntosh won her second gold medal of the championships, beating American Katie Grimes by 0.63 seconds.
She became the first Canadian swimmer to win two gold medals at a single World Championships, and set a new record for the most medals won by a Canadian at a single World Championships (4), which would be tied later that same day by Penny Oleksiak and Kayla Sanchez.
2016
This was both a national and Commonwealth record, and the third-fastest of all time, as well as the fastest time recorded by any swimmer since Katinka Hosszú's winning time at the 2016 Summer Olympics.
At the national swimming trials, McIntosh won titles in the 200 metre and 400 metre freestyle, the 200 metre butterly, and the 400 metre individual medley, before scratching from the 800 metre freestyle.
McIntosh made her senior FINA World Aquatics Championships debut at the 2022 edition in Budapest, Hungary, with her first event being the 400 metre freestyle.
She finished second in the final, taking the silver medal with a new personal best and national record time of 3:59.39.
She was only the fourth woman in history to record a time of under four minutes.
McIntosh set another world junior record in the semi-final of the 200 metre butterfly with a 2:05.79 time, exceeding her own as-yet-unratified record from the Canadian swimming trials.
She broke the record again the following day, June 22, in the event final, claiming her first World title, the first medal of any colour for Canada in the event.
2020
McIntosh first drew recognition when, at age 14, she was the youngest member of the Canadian team for the 2020 Summer Olympics, where she achieved a notable fourth-place finish in the 400 metre freestyle.
The following year she became the youngest World Aquatics champion in swimming in over a decade, and the first Canadian to win two gold medals at a single World Championships, for which she was dubbed a "teen swimming sensation."
In March and April 2023, in the span of five days, she set her first and second world records, in the 400 metre freestyle and 400 individual medley events, at the Canadian national trials.
McIntosh is the daughter of Greg McIntosh and former Canadian Olympic team swimmer Jill Horstead.
Her older sister Brooke is a competitive pair skater.
McIntosh has broken over 50 age group national swimming records.
In May 2021, McIntosh swam a 4:05.13 in the 400 metre freestyle, the fastest time ever by a 14-year-old swimmer worldwide.
She currently holds the world record in the women's long course 400m IM.
As part of the 2021 Canadian Olympic swimming trials in Toronto, McIntosh won the 200 metre freestyle event over training partner Penny Oleksiak, with a personal best time of 1:56.19, which also marked the fastest time ever by a 14 year old swimmer worldwide.
This qualified her for the 2020 Summer Olympics in Tokyo.
McIntosh followed this up with a win in the 800 metre freestyle event, in another personal best time of 8:29.49.
She was the youngest person named to the Canadian Olympic team.
In her first event, McIntosh finished fourth in the 400 metre freestyle, breaking the Canadian national record with a time of 4:02.42.
She advanced to the semifinals of the women's 200m freestyle, but placed ninth there and thus missed the final.
She was part of the Canadian team for the 4 × 200 metre relay, along with Oleksiak, Rebecca Smith and Kayla Sanchez.
They set a new Canadian record in the event final, placing fourth.
McIntosh's last event was the 800 metre freestyle, where she placed eleventh and thus did not advance to the final.
Following the Olympics, McIntosh made her debut on the International Swimming League as part of the Toronto Titans.
McIntosh was part of the Canadian team for the 2021 World Short Course Championships, and won a silver medal as part of the 4×100 metre medley relay, where she swam in the preliminaries for Canada as the team finished in second in the final.
She then helped the Canadian team in the 4×200 metre freestyle relay, swimming the first leg as Canada won gold.
McIntosh won her first individual medal of the competition when she won the silver in the 400 metre freestyle race.
She was third at the halfway mark but passed Siobhán Haughey and held on to the second position, finishing behind Li Bingjie.
McIntosh had set a Canadian record in the 800 metre qualifying, but she withdrew from the event to focus on the 400 and women's relay events.
On March 4, 2022, McIntosh swam the 400 metre individual medley at a preparatory event for the Canadian swimming trials, recording a time of 4:29.12.
