Freediver Mandy Sumner is back in Maine after setting a Guinness World Record on March 2 in Norway for the longest bi-fin swim under ice by a woman in a swimsuit. Sumner, 46, is a native of North Berwick who now lives in Sanford. Gregory Rec/Staff Photographer

Mandy Sumner was swimming underwater, in a frozen lake, with a sheet of ice 19 inches thick a few feet above her head. And she needed to hold her breath for more than a minute.

The instinct to quit, as one would imagine, kicked in. It often does.

“You just have to get past that,” she said. “I would sing a song in my head, or count my strokes. It keeps my brain busy, from not thinking about ‘I don’t want to do this.’ ”

Seventy-five meters later, Sumner resurfaced, having set a Guinness World Record for the longest bi-fin swim under ice by a woman in a swimsuit. No wetsuit, mind you, even though the water temperature was 35 degrees. The 46-year-old North Berwick native accomplished the feat on March 2 at Lake Mysutjernet in Norway.

As for why she did it? After a chuckle, Sumner had a reason.

“The simple answer is why not?” she said. “But the more complex answer is that I love being in the water. Cold or warm. … I wanted to do something again that was important to me.”

That love of water was honed by a childhood spent swimming in Maine pools, and has led to a passion for freediving, a sport in which swimmers and divers push themselves to cover extraordinary depths and distances underwater.

For Sumner, the more time she can spend in water, the better.

“I’ve always been a water rat,” she said. “In the ocean, in the pool, my whole life.”

Sumner’s freediving abilities have impressed the people she’s met in her travels.

“She has good technique and she has good stamina, and she managed to keep calm in the cold,” said Arve Gravningen, a Norwegian freediving shop owner and coach who organized the event. “Eighty percent of (freediving) is between the ears. It is helpful to have good breath hold and have good technique, but if your head’s not in the right place, you don’t really get anywhere.”

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Growing up, Mandy Sumner created opportunities to swim that weren’t there before her. She joined the Sanford Titans club swim team at age 5 and continued swimming there until graduating from high school, and upon going to Noble High School – which didn’t have a team – started one that practiced with Sanford and Massabesic.

“Swim team was my life,” she said.

Sumner shelved her swimming career when she went to the University of Southern Maine, where she played collegiate soccer. But when work brought her west to Hawaii in 2009, she returned to the water and began scuba diving. In 2013, she heard that the founder of the United States women’s freediving team, Annabel Edwards, led a group that met each week to go diving in Honaunau Bay.

Mandy Sumner set a Guinness World Record on March 2 at Lake Mysutjernet in Norway, in water that registered 35 degrees. Heidi Vaule photo

Freediving requires divers to hold their breath, rather than breathing with scuba gear. It’s a niche sport in the United States, but has a more fervent following in Europe. It offers competitions based on how deep divers can go underwater, either by swimming or pulling themselves along a rope, and how long they can hold their breath.

Sumner had given it a shot earlier with two friends, swimming down 110 feet to a wreck she had visited while scuba diving.

“My first dive that I did, they put their dive watch on me … and I went down to the wreck, stood on the wreck and then came back up, and they were like ‘Where did you go?’ ” Sumner said. “They didn’t expect me to go that deep.”

Sumner met Edwards two weeks later, and soon began flying from Oahu to the Big Island every weekend to meet with her. Sumner, who lost her mother in 2008, called Edwards her Hānai – Hawaiian for “adopted” – mother.

“Mandy is a natural,” Edwards said. “First day out, (you could tell) this person has the ability. … You have to be able to equalize your eardrums. She was able to equalize, she was a competitive spirit, and (she was) comfortable in the ocean.”

In 2014, Sumner started freediving competitively. By September, having qualified at events in Hawaii and Honduras, she was competing for the U.S. at the world championships in Italy. In 2015, she went to the individual world championships in Cyprus and won the gold medal – the only American ever to do so – with a no-fins dive of 58 meters (190 feet) in depth.

Mandy Sumner swims underwater at Lake Mysutjernet in Norway. Video still by Arve Gravningen

By that time, Sumner was hooked. She split her training between Hawaii and Egypt, and followed up Cyprus with competitions in Greece, Egypt and Mexico within the span of two months, dipping into her savings and, in one case, opening a GoFundMe platform to support the travel.

“I just loved the feeling of being underwater,” said Sumner, who says she can hold her breath for five and a half minutes. “The deeper you go, your body acclimates to it in different ways. … It’s very peaceful underwater. It’s just you with yourself, and that was something I really enjoyed.

“It really was a passion. And then I was really good at it, so things were working.”

“I always had this weird fear since I was a kid that I was going to fall through the ice and never get back through the hole,” Mandy Sumner said. “That’s kind of why I kind of wanted to do this, in a safe way. To see what it’s like.” Heidi Vaule photo

By Mexico, however, she had hit a wall. Routine dives became challenging. She ramped down over the next three years and began freediving mostly for fun and as a hobby. Mostly, she concentrated on her career as a geographic information systems analyst for utility companies, working on mapping and data migration.

“I had really top freedivers, world record holders and world champion freedivers telling me I was doing too much and I needed to slow down,” she said. “But I didn’t listen. It got to the point where I had to listen.”

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Even after she moved away from competing, Sumner still managed to attend freediving events and work as a coach, judge and safety diver. At one event in Iceland in 2019, she put on a pool competition and met Amber Fillary, a South African record holder for under-ice swimming. Sumner began coaching Fillary in later events and met Gravningen, the Norwegian freediver, while experimenting with swimming in cold water. Having seen what Sumner had done in competition, Gravningen worked to persuade her to go for a record.

Sumner said she found the right headspace in late 2023, after she had a miscarriage earlier in the year. The ordeal strained her mental health, but she found the relief she needed by giving herself the challenge of trying for a world record.

Mandy Sumner smiles after completing the longest bi-fin swim by a woman under ice in a swimsuit on March 2 at Lake Mysutjernet in Norway. Heidi Vaule photo

“It was a struggle last year. I’m finally working my way out of it, and I feel like this is a huge part of it, to set a goal and work towards that goal,” she said. “It was a distraction, but also very healing. … Any time I get in water, if I’m having a bad day or anything, being in water takes things away. It takes sadness away. It takes bad thoughts away.”

Sumner, who has been living in Sanford since the pandemic, started working three times a week with Emily Koehler, a strength and conditioning specialist, through MaineHealth’s Sports Performance Center. Their focus, with a record in mind, was on land workouts, developing upper body and core strength, and injury prevention.

“Looking at her when she walks in the door … she has a super strong build,” Koehler said. “She’s genetically built for it. … She can put on muscle, she can create power. She’s very, very athletic.”

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As a child in Maine, Sumner had no interest in icy water. Far from it.

“I always had this weird fear since I was a kid that I was going to fall through the ice and never get back through the hole,” she said. “That’s kind of why I kind of wanted to do this, in a safe way. To see what it’s like.”

Sumner arrived in Norway on Feb. 18, and began working with Gravningen to prepare for the dive. They worked on how to maintain her breathing in the cold water. By going underwater too soon, she wouldn’t have enough breath to reach 75 meters (246 feet). By waiting too long, she’d waste precious energy treading water.

And then, of course, there was adjusting to the cold. To get the record, Sumner would have to wear a swimsuit, not a wetsuit, so her skin would be exposed. According to the Personal Floatation Device Manufacturers Association, hypothermia in extremely cold water can lead to unconsciousness in about 15 minutes.

“It’s shocking if you’re not used to it, and you want to get right out,” Sumner said. “It took me about a week and a half to acclimate to it. … I just had to focus my head on ‘Yep, this is just ice water, it’s cold water, you can do it.’ ”

Sumner went for the record along with three others looking to set world marks in different categories. The work prepared her. But on the day of her record bid, after she entered the water, she felt her composure unraveling.

Mandy Sumner at Lake Mysutjernet in Norway, where the ice was 16 inches deep on March 2. She swam 75 meters to establish a new world record. Heidi Vaule photo

“My nerves definitely took over,” she said. “I had been trying all week to slow my kicks down so I wouldn’t go so fast, so I wouldn’t burn as much energy. That all went out the window. I got in there and I basically sprinted.”

The ice Sumner swam under had holes cut out every five meters, in case she ran out of breath along the way and needed to resurface. She had to push through the temptation to pull up early.

“At the very beginning of that dive, I didn’t get a full breath,” said Sumner, who had Gravningen swimming alongside her in scuba gear for safety. “Around 30 meters, I felt like I didn’t have enough breath. But as soon as that feeling came up and that thought came up, I just started singing a song in my head and counting my kicks, just to distract my brain. I knew I could do that dive. It was only a minute and 15 seconds, and I know I can hold my breath that long.”

Sumner surfaced on the other end with a sense of pride, to cheers. She now awaits Guinness World Records verification.

“It was a really good celebration and a great feeling,” she said. “I was just happy, and I had a huge smile on my face. I was really proud of myself for saying I was going to do this, and I did it – and showed people that it’s possible to do crazy things like this. If you’re determined to do something, you just put your mind to it and you can get it done.”