How Daisy Ridley’s swim coach prepped the star for Young Woman and the Sea

In August 1926, American champion swimmer Gertrude “Trudy” Ederle became the first woman to swim the English Channel, completing the 21-mile feat in 14 hours and 34 minutes—a record that would stand until 1950. She was just a few months shy of her 21st birthday. It’s the kind of classic sports story tailor-made for the silver screen, and Disney has obliged with its new biopic The Young Woman and the Sea, starring Daisy Ridley as Ederle.

The daughter of a butcher in Manhattan, Ederle learned to swim in New Jersey and joined the Women’s Swimming Association (WSA) at the age of 12. She quickly excelled at the American crawl stroke, setting the world record in the 880-yard freestyle that same year—the youngest swimmer to do so. She would go on to hold 29 US national and world records between 1921 and 1925. She competed in the 1924 Summer Olympics, winning gold in the 4×100 meter relay and bronze medals in two other individual races.

After her Olympic triumph, Ederle became a professional swimmer, completing the 22 miles between Battery Park to Sandy Hook in 7 hours and 11 minutes in 1925. Her nephew would later describe it as a “warm-up” for swimming the English Channel. The WSA sponsored Ederle’s first attempt that same year, but her trainer, Jabez Wolffe, ordered her pulled from the water, disqualifying the attempt. Ederle was angry about that decision and found a new coach in Bill Burgess for her second attempt. This time she succeeded and was rewarded with a ticker-tape parade in Manhattan with some 2 million people cheering her on.

Ederle tried to capitalize on her renown, making a cameo in the 1927 silent romantic comedy Swim Girl, Swim and joining the vaudeville circuit but did not meet with much financial success, further exacerbated by the Great Depression. After injuring her spine in a fall, she was bedridden for several years. She was almost entirely deaf by the 1940s, thanks to a childhood bout with measles, and spent some time teaching deaf children to swim. Ederle died in 2003 at the age of 98.

Directed by Joachim Rønning (Maleficent: Mistress of Evil, Tron: Ares), The Young Woman and the Sea focuses on Ederle’s early life, culminating with her successful Channel Swim. The role naturally required Ridley to undertake extensive swim training for several months and throughout the filming in Bulgaria, although she already knew how to swim. Preparing her for that task fell to Siobhan-Marie O’Connor, a British champion swimmer whose many accolades include winning a silver medal in the 200m individual medley at the 2016 Rio Olympics—just 0.3 seconds shy of the gold and the first British woman to medal in the event.

“I loved being a part of the film,” O’Connor told Ars. “It is such a beautiful story, and Trudy was a trailblazer for women’s swimming and women’s sport in general. To have the opportunity to work on this production was incredible. Daisy’s preparation, the way that she committed to all of the training, was really impressive, and it was an absolute pleasure to work with her.”

The film covers different parts of Ederle’s career, including her earlier days as a competitive swimmer in pool competitions: initially in galas and local competitions in New York and later in the Olympics. “There were so many different swimming elements to the role, so it meant that training had to be really, really varied,” said O’Connor.

O’Connor initially focused on fine-tuning Ridley’s swimming technique. “If your stroke is not efficient and you’re too low in the water, you’re never going to be able to have that sort of open-water technique,” she said. This helped ensure that Ridley felt comfortable before O’Connor moved on to building up the actor’s fitness level. The latter included plenty of endurance sessions, speed sessions, and the occasional recovery session.

Swimming in open water is very different from swimming in a pool, both in terms of technique and physiology. Swimmers must contend with strong currents, unpredictable weather, and possible hypothermia or jellyfish stings. “We would do some speed sessions to focus on a fast pace for scenes where Trudy’s competing in the 4×100 freestyle at the Olympics,” said O’Connor. “That’s a very different stroke from an open water, middle-of-the-Channel swim. For the open water technique, we did a lot of work on Daisy floating her legs back. That involved a lot of upper-body strength.”

Another key aspect was making sure Ridley was able to lift her body while swimming in open water to see where she was and whether she was still on course with regard to the tracking boat following along. “It’s really hard to be able to do that,” said O’Connor. “You have to have a solid foundation of fitness and technique to be able to lift your body out of the water constantly. But you need to be aware of your surroundings so much more than you do when you’re in the pool.”

As for the pool scenes, in Ederle’s day, competitive swimmers didn’t wear goggles. Ridley nonetheless often wore goggles given the extent of her training. “It just would’ve been awful for her eyes to be in chlorinated pools without goggles one hundred percent of the time,” said O’Connor. That said, she did make sure Ridley practiced swimming without goggles “to know how that was going to feel come the day of the shoot, where you’re going to have to swim without.”

The hard work paid off. “When Daisy got to swimming in the open water, she was confident and comfortable in the sea, and the fitness is a big part of that,” said O’Connor. “I thought about it as if it was myself preparing, I’d want to feel that my fitness was as good as it could be for preparing for something like that.”

So would O’Connor herself one day aspire to swim the English Channel? She retired from competitive swimming in 2021 but admits she’s considered the prospect, perhaps in a relay medley format. “It’s one of those things where people are always trying to push the boundaries and take on an even greater challenge,” she said. “I would never say never. But I would need to get back in and train properly.”

The Young Woman and the Sea is now playing in select theaters.