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Ponce de León's search for the fountain of youth in Florida is just a legend.

But about 1,500 miles to the north, in the icy waters of Cedar Lake in Minneapolis, dozens of people think they've found the next best thing.

On a recent Sunday around 9:30 a.m., a diverse group of about 20 people dressed in swimsuits trekked to a spot near the shore on the west side of the lake and immersed themselves in an 8-by-12-foot rectangular hole cut in the ice. Later in the day, another group of people gathered to do the same thing.

This isn't a once-a-year, get-in, get-out, New Year's Day plunge for Instagram bragging rights.

This is something that happens every Sunday throughout the winter.

Some people come several times a week, and stay for a good, long soak of five, 10, 15 minutes or more. Except for the knit hats, they look like they could be relaxing in a hot tub as they stand in water that ranges from waist- to neck-deep.

Called cold therapy or cold thermogenesis, ice-water bathing is a practice that biohackers and assorted others believe makes them healthier.

The Twin Cities Cold Thermogenesis Facebook group, which was created in 2016, claims the frigid dips do everything from increase testosterone in men to boosting brown adipose tissue. (The so-called brown fat or "good" fat may be helpful in combating obesity because it burns calories to create heat.)

Cold-water immersion also strengthens the immune system, according to Svetlana Vold, a part-time firefighter and ultramarathon winter bike racer from St. Louis Park, who organizes the Sunday morning cold-immersion session.

Vold and others say chilling out in the water combats inflammation, helps them sleep better and improves their focus and endurance. Some said they're inspired by Wim "The Iceman" Hof, a Dutchman famous for his breathing and cold exposure technique called the Wim Hof Method.

The Cedar Lake group would probably meet the approval of David Sinclair, a Harvard genetics professor and longevity expert who thinks that cold exposure may help slow the aging process.

Maria O'Connell, the organizer of the afternoon session, has been immersing herself in an ice-filled horse trough in her backyard since 2011. "Initially it's a little uncomfortable," she said. "You end up getting better the more you do it."

But many say the frigid dunks are a mood-altering, even pleasurable experience.

"It hurts so damn good," said Stephen McLaughlin, a 61-year-old Minneapolis resident. "You are just completely present."

"It makes me happy. I think it's adrenaline," said Allison Kuznia, 42, of Minneapolis.

"It's kind of a treat to go out and get really cold," said Nick White, 46, of Minneapolis. "It gives you a feeling of euphoria."

Richard Chin • 612-673-1775 @rrchin