Plunge into water at near-freezing temperatures, and your body goes into extreme distress. Your skin screams signals of pain. You can't breathe, because your chest is cramping up.
Talking is nearly impossible. Your heart is pounding. Fear mounts -- as it should. Without any protection, you may lose consciousness in under 15 minutes. You'll be dead within an hour.
Or ... you can start racing! That's the idea behind the Open Scandinavian Championship in Winter Swimming, which takes place every year in a 25-meter pool cut out of a frozen lake in a small Swedish town only about 100 miles from the Arctic Circle.
Nearly 400 swimmers traveled there in February for the privilege and thrill of competing in this unique sport with as many health benefits as risks, it seems.
It's the health benefits of the cold -- both physical and emotional -- that inspired this winter swimming race in the first place.
Lars Westerlund, a founder and current organizer of the race, is also the chairman of the Society for Happy Friends of Cold and Darkness, dedicated to embracing the sub-zero temperatures and sub-sunshine days of the region. The Happy Friends want to give travelers reasons to venture that far north.
Theirs is a yin and yang understanding of darkness and cold. It's actually the light of a region so dark in the winter that is amazing: the long blueish dawn of a three-hour day and the unique way light reflects off the snow. And it's the health benefits of cold that are the attraction, particularly for winter swimming.
Risks, rewards and a very natural high
"People get less sick when they dip," said Westerlund, who has been tracking down experts with cold weather specialties and inviting then to present seminars at next year's race. There's not a lot of published research on the topic, but one recent study found that individuals who regularly took cold showers reported fewer sick days than warm-water bathers.
There is some evidence that cold water exposure builds immunity, but it's not conclusive. It's also not clear whether cold water therapy, as it is called, burns more calories, though one former NASA scientist swears that it's helped him drop 30 pounds.
Westerlund has extended an invitation to a professor who's been measuring the increase of brown (i.e. good) fat among his cold-water dipping students at the Linköping University in Sweden.
There is some scientific evidence that cold water can help fight off stress, depression and insomnia, though. Endorphins -- hormones created in the brain and nervous system -- are released in the body when it hits cold water; they reduce pain and are considered a natural antidepressant.
"I was surprised to learn just how good I felt afterward," CNN Chief Medical Correspondent Dr. Sanjay Gupta said of his own jump into cold water 270 miles north of the Arctic Circle.
He was with hypothermia expert Dr. Mads Gilbert, who told him "that my body had just released more endorphins than a warm water swim, explaining the 'cold water high,' and additionally my metabolic activity was higher, allowing me to burn away more fat."
The psychological benefit of winter swimming may be related to conquering one's fear in face of pain and life-threatening conditions. Plunging into cold water also induces Zen. "You empty your brain," Westerlund said of the experience. "It's just survival."
But the greatest joy may be the feeling of getting out of the water and getting warm again. The juxtaposition leaves people feeling energized, giddy and even serene for hours afterward.
"When I come up, after swallowing half the river and with the beard full of icelings, it is a lot of laughing, primal screaming and cursing," said swimmer Enar Nordvik of northern Sweden, who was a on a team with co-workers. "Like walking to your own execution but becoming free."
Westerlund says that "the people who have never done it before are very tense. But when they come out of the water they are very happy. It's like taking a joint. Everything is in harmony. It's a very special experience."
There are serious health risks to cold water immersion, of course. Hypothermia can kill you. Panic can lead to drowning, especially in open water.
Swimming below surface ice carries a high risk of being trapped underneath. Swimmers looking to take up the icy waters should consult their doctors, as the sport could be fatal for someone with a heart condition.
If you add racing to the mix, there is the additional thrill of competition. There's also less risk of dying with organizers and a fully equipped emergency diver on hand. It helps that most of the racers are out of the water in less than two minutes.
Ice, ice, baby
The first year of the Open Scandinavian, in 2012, 32 swimmers came from five countries to Skellefteå, Sweden, to compete. The town of 42,000 people is quite remote, a nine- to 10-hour drive from the capital, Stockholm. Skellefteå is surrounded by pine and fir trees as far as the eye can see.
"At the beginning, people thought we were just crazy," Westerlund said. The outside temperature for that first competition was minus 36 degrees Celsius (minus 32.8 Fahrenheit).
This year, it was a balmy minus 10 degrees C (14 F). But the temperature in the River Skellefte is about the same every year they race: 0.2 C (32 F) degrees this February. To be clear, that's 0.2 degrees shy of the water turning into ice.
The ice on the surface, more than 2 feet thick, had been cut by a team of laborers with chainsaws. It took a week, but we're told that, unlike the opening of the hit Disney movie "Frozen," there was no singing that accompanied the ice cutting.
The first organized winter swim competition took place in Finland in the 1980s, and it has been gaining glacial traction. The Swedish race is now one of five winter swimming competitions in the World International Winter Swimming Association World Cup -- along with other host countries Russia, Lithuania, Estonia and Great Britain -- between October and March.
There is a world championship race every other year, and the association is pursuing Winter Olympics dreams.
Sweden may also be the coldest of the championship races, with only Russia giving it a run for that superlative. Winter swimming has a longer tradition in Finland and Russia, but this race is the first of kind in Sweden, beginning a tradition and putting a unique spin on it.
In past years, there have been lectures on cold and darkness, snow-angel making and "child curling," in which kids ball themselves up and are slid toward targets on the ice.
This year, there was a poetry contest. Artists moved by a love of the cold recited their verse while treading in the near-freezing river. A winner was declared, but alas, her poem has not been translated into English.
On the day of the race, nearly 400 swimmers from 21 countries made their way to the 25-meter natural ice swimming pool from the changing area inside City Hall, on the banks of the river.
After the races, they went back into the building for a disco dance party at which reindeer was served for dinner.
Many swimmers were sporting creative and/or funny hats to compete for the best hat award. Hundreds more came out to watch and cheer for them from the water's edge.
"It is a beautiful cold place with very warm people around" is how Christof Wandratsch of Germany described the scene.
The race day consisted of three individual races: a 25-meter breaststroke, freestyle and butterfly, a 50-meter breaststroke and freestyle, and a 100-meter freestyle.
Races are grouped by age, a range this year of swimmers born as recently as 2004 and as long ago as 1940. A fourth race was a relay with teams of four (with at least one member of a different gender than the others), each doing a single lap. With more than 40 teams, the co-ed team race was the most popular.
The fastest lap was completed in 12.89 seconds by Rauno Pärg of Estonia. Silver, gold and bronze medals were awarded to those with the fastest times, but there's no prize money.
The more professional racers have sponsors, but the race is also open to newcomers. Some were there because a loved one (or nemesis?) gave them an entry spot as a gift.
Swimmers can't drink alcohol before a competition, or have the flu that day. They can't wear wetsuits, gloves or any footgear. But all of them must wear a hat, for body heat retention.
This year, one of the swimmers won recognition for best hat, in the shape of downtown Skellefteå landmarks.
Taking the big plunge
If you want to get into the sport, talk to your doctor, even if you are already active and a good swimmer. Then find safe places to swim, public areas with other swimmers year-round.
Westerlund suggests starting your winter swimming training in warmer months so that you become acclimated to the cold as the seasons change. Even taking regular cold showers helps prepare you for race day.
The ability to swim in cold weather is as much about physical fitness and learning how to breathe quickly to fill your lungs as it is about training yourself psychologically to do something painful and panic-inducing. It's truly mind over matter.
And remember, the reward is like a sunken treasure in a sea of pain, just as the light is made more beautiful when it's surrounded by darkness.
