‘Excitement With a Little Dash of Fear’: Polar Plunges Ring in the New Year With a Splash. But What Actually Happens to Your Body?

The scene at the Vancouver Polar Bear Swim, one of the oldest polar plunges in the world, is a jubilant one. On Canada’s English Bay Beach, people come dressed in costumes, veteran participants bear dozens of commemorative buttons from plunges past, and every year the tradition grows. For these intrepid, some might say ill-advised, adventurers, celebrating the new year means throwing themselves into frigid water. In 2025, the plunge’s 105th year, more than 13,000 people gathered to take a dip in the 44-degree-Fahrenheit bay.

“It truly is a fresh start for the new year for a lot of people,” says Tanya Donaldson, aquatic services team lead for the Vancouver Board of Parks and Recreation and part of the team responsible for the plunge. “As big as it is, it creates its own special community.”

What’s the appeal of such a physically shocking tradition? For many, it’s a sense of connection with the other swimmers. It’s not uncommon to see three or four generations of a family running into the water at once, says longtime plunge participant Lisa Pantages. Her grandfather, Peter Pantages, started the Vancouver Polar Bear Swim in 1920, when he ran into the bay with a small group of friends. Lisa herself has been a constant fixture at the event—2026 will be her 64th New Year’s dip.

There’s an “energy of excitement with a little dash of fear,” she says. “When you watch all these people running out of the water, you see how proud they are and excited and connected to the rest of the crowd. In a way, it’s pretty amazing.”

The plunge came out of Peter Pantages’ habit of swimming every day. As an immigrant, ocean swimming gave him a way to stay connected to his home in Greece. “He was a very disciplined man,” Pantages says, even maintaining his habit when traveling by ocean liner.

“He made an agreement with [the liner company] that he would be able to dive overboard every day and swim in the ocean,” she adds. “If it was too rough or deemed too dangerous for him to do that, they would ice and salt down a giant bathtub to the temperature of the ocean that day, and he would lie in it for like 20 minutes.”

In the 106 years since the first organized plunge, the Vancouver Polar Bear Swim has become a full-fledged festival that some participants travel to experience. There is even a man who plays the bagpipes every year, topping the instrument with a polar bear costume head, Donaldson says.

Vancouver’s swim is hardly the only one of its kind: The L Street Brownies have been plunging in Boston since 1904, and people in Scotland participate in a “Loony Dook”—essentially, a “crazy bath”—to ring in the New Year, just to name a few.

Halfway around the world from Vancouver, in the village of Egmond aan Zee on the coast of the Netherlands, the story is much the same. Crowds gather and rush into the North Sea, then follow their plunge with soup to warm up.

“We make it a fun day for all,” says Tom Valkering, one of the plunge organizers. “After 10 or 15 minutes of jumping and singing and dancing, we all together go to the sea. … It’s a fairly lovely day. It’s really cold, it’s hard, but it’s a nice start of the year.”

As polar plunges have become New Year’s traditions around the world, many people report having positive experiences—after all, they keep coming back. But from a science perspective, the practice is a lot more complicated, especially as influencers tout the supposed health benefits of cold-water immersion.

“At the moment, in terms of the science, the evidence that we have is very much around the problems of cold-water immersion and the risks to our health. There’s far less research about the potential for benefit to health,” says Heather Massey, an extreme environments researcher at the University of Portsmouth in England. “It doesn’t mean that people aren’t benefiting, of course, but the science really is lagging behind at the moment.”

For both one-time plungers and those who make it a habit, it’s important to be very aware of what your body is telling you while plunging. We asked doctors and scientists about what happens to your body when you take a polar plunge—as well as the risks and whether the tradition has any benefits. Here’s what they had to say.

What happens to your body during a polar plunge?

When you first get into cold water, it may feel like it takes your breath away. That’s because it does, in a sense: The abrupt drop in temperature your body experiences when you enter cold water triggers a reaction called cold shock. It’s driven by a rapid reduction in skin temperature, which initiates your fight-or-flight response.

This stress reaction, led by your sympathetic nervous system, brings with it a big increase in the hormones adrenaline and noradrenaline, which in turn drive up your heart rate and blood pressure. Blood vessels constrict to preserve heat and shift blood toward vital organs.

Due to cold shock after a sudden, frigid dunk, people often take a big gasp, followed by fast breathing—it can feel like you have no control over your breath. And if that gasp happens while submerged, the resulting lungful of water can be deadly.

“Cold shock is so debilitating. When you accidentally fall into cold water, lots of people start to panic,” Massey says. “That panic can mean that people inhale water, and that can cause a drowning process,” even in confident swimmers.

This natural reaction is the biggest risk associated with cold plunging, says Mark Harper, an anesthesiologist in the United Kingdom and Norway who plunges regularly and wrote a book about the pastime. Cold shock peaks in about 30 seconds and can last three to five minutes, Massey says.

“If you’re young, fit and healthy, it’s just going to be an uncomfortable feeling, an uncomfortable experience,” Massey says. “But for someone with underlying respiratory or heart conditions, these could exacerbate their condition.” People with heart conditions might be taking beta blocker medications, which could make it more difficult for their bodies to adapt to cold shock. Experts recommend being checked out by a doctor before cold plunging.

Even if it is not a health risk, the instinctual response to cold exposure can be alarming, Massey says. “We suggest that you go in slowly and gradually rather than jump or dive in,” she adds.

Entering the water slowly can help you control your breathing, says Harper. “When I walk in, immediately I start exhaling,” he says. “Basically, I’m telling my body, ‘I got this.’” By regulating his breathing, Harper is trying to stimulate the parasympathetic nervous system, which oversees the so-called rest-and-digest response that helps the body return to a balanced state after the fight-or-flight reaction.

Repeated dippers will notice that the cold shock response lessens with just a few exposures. And the reduced reaction to cold water—marked by lowered heart rate and speed of breath when submerging initially—sticks around for months, according to a review of several studies.

What are the risks?

Cold shock is the biggest and most immediate risk of a plunge, but prolonged time in frigid waters comes with additional hazards.

After your skin gets cold, the nerves and muscles near the surface also get chilly, potentially making you less coordinated. This reaction, called cold-water incapacitation, can lead to loss of muscle control, leaving a person unable to do a solid swim stroke or climb a ladder. “That is not good in terms of being able to successfully exit water,” Massey says.

It’s best to “know how you’re going to get out before you get in,” she adds. For people dipping through a hole cut in ice, Harper says a triangle is the easiest shape to climb out of.

“People underestimate how energy-sapping being in cold water can be,” Massey says. “Just be aware that you’re not going to be a stronger swimmer or dipper than you are in swimming pool water.”

The Red Cross of Canada recommends always having someone on dry land to keep an eye on you while you are in the water in case of emergency—and it’s best to have medical personnel nearby, too.

Humans lose body heat 25 times faster in water than in air, because the density of water makes it conduct heat much more easily. And when someone is in cold water for long enough, they can develop what might be the most commonly known risk from polar plunging: hypothermia.

Hypothermia sets in when the body’s core temperature drops below 95 degrees Fahrenheit. You’ll lose heat in any water that’s below your body temperature, and hypothermia can happen even in somewhat warm waters, given enough exposure time. But in water that’s less than 50 degrees, it might take only minutes.

That’s why, for a polar plunge, you don’t need to be in the water for long. “I always say, in ice water: Two to three minutes, that’s all you need,” says François Haman, an extreme environments researcher at the University of Ottawa.

Young children, the elderly and people with lower body weights are more at risk of hypothermia, according to the Red Cross of Canada. And as the core body temperature drops, increasingly extreme symptoms appear, from shivering to slurred speech, slowed breathing, lack of coordination and loss of consciousness. People with hypothermia also suffer mental effects, like confusion and memory loss.

When it comes to a polar plunge, hypothermia is the risk that takes the longest to come to pass, Massey says, making it a comparatively smaller concern for safety researchers. Cold shock and cold-water incapacitation are more pressing issues. But safely warming up your body afterward is key, because some of hypothermia’s risks can set in even once you’re back on land.

Recovery: Warming up post-plunge

After you get out of the water, your body temperature can continue to drop.

“Your coolest deep body temperature is going to be some 30 to 50 minutes after you’ve got in the water,” Massey says. In that time, “People might be doing lots of different things, like driving home, for instance, or cycling. And if that’s the point at which your mental faculties start to reduce, then that could not only be problematic for yourself, but problematic for others.”

Drying off and getting dressed quickly, as well as getting out of wintry environments, can help. So can exercising—it’s one of the most efficient ways to generate body heat, Massey says. “It doesn’t stop the continued cooling, but it might make your whole recovery quicker.”

Massey does not recommend getting into a warm bath, for example, or doing other activities that immediately stop your shivering response. A warm bath raises your skin temperature and stops shivering, but it doesn’t address your deep body temperature as effectively.

Everyone’s response to cold—and how they recover from it—is going to be a bit different, Haman notes. Some people shiver more in their upper body; some shiver more in their legs. Some people have more brown fat, a type of fat that your body can burn to produce heat. Everyone who polar plunges will warm up a bit differently, so experts say it’s important to pay attention to your body throughout the process.

Are there any benefits of a polar plunge?

People who cold plunge often tout the benefits they feel, with some pointing to reduced inflammation, better focus and faster recovery from exercise. But those claims currently have little to no scientific backing.

“There are lots of stories in my book from people who really benefited from it. We haven’t got the sort of hardcore studies for that now,” Harper says. “There’s a lot of noise, and all that noise is positive.”

Some research does indicate plunging can help reduce soreness and inflammation post-workout, maybe as a result of the rapid constriction of blood vessels, but other physical benefits lack robust research. There is, however, some research into mental health benefits, Haman says.

“What we know really, really well is cold will stimulate your sympathetic nervous system. So cold will wake you up and make you more, you know, active and just take you to a different level,” Haman says. “We also know that dopamine is being released, which is a feel-good hormone, and we also know that serotonin is being released, which is … a natural painkiller.”

Still, Haman and Massey warn against believing everything you see on social media when it comes to cold plunging. “We’ve got to be careful about what conclusions people are drawing,” Haman says.

“The problem is someone can post something on social media and say, ‘This is amazing. This is great.’ And it can go viral in seconds,” Massey says. “But research takes years to get the funding, to get all of the work together, to come out with the same results.”

Plungers on social media might also emphasize pushing through and staying in the cold for longer and longer, a practice that isn’t advisable or beneficial, Haman says.

“You don’t need to be in there more than the duration of the cold shock,” Haman says. “You do your 30 seconds, and then maybe extend to a minute and a half, maybe push it to three, and then you’re out.”

Though the science doesn’t totally back it up yet, the experience of cold plunging, when done safely, can leave people feeling good, he adds. Many things might contribute to this feeling, including the social experience and being outdoors.

“People do feel that they’ve done something amazing. People do feel really, really good when they do cold dipping,” Haman says. “I’ve seen it multiple times—smiles on their faces, super excited, happy to have done it.”

With the proper precautions, a one-time polar plunge is “really you just having a bit of fun,” Harper says. “Fun is good for you.”

Haman commends a mindful attitude when plunging, not one that makes you push through alarm bells.

“At the end of the day, this is all about self-awareness,” Haman says. “This is all about you listening to your body and optimizing your capacity to put yourself in discomfort—but doing it safely.”