Outsiders may regard them as stupid. Or crazy. Or both.

But the Pittsburgh Polar Bears, the 400 or so human holiday revelers who will ring in 2009 with a frigid swim in the Monongahela River, claim there's no better way to start the new year.

True, the Mon is far from clean, but Frank Nelson, the club's president and a 40-year veteran of the tradition, says the plunge is sort of like an annual baptism.

"You're cleansing yourself," Nelson said, with a laugh, adding that it's a great way to nurse the unfortunate side effects of New Year's Eve overindulgence.

In Crawford County, at Pymatuning Lake, the Greenville Area Leisure Services Association holds the Jump in the Lake Incident in early February, a fundraiser for GALSA and for the Jamestown Future Foundation, which maintains the Gibson House, an old mansion holding the community's library.

The lake, with water that has registered as low as 28 degrees, is usually frozen over, so park officials have to cut a large hole in the 8-inch-thick ice for the jumpers.

The legend behind the "incident," concocted by GALSA executive director Erik Bieleta, may be more outrageous than the event itself:

In Bielata's version of the story, the Gibson House used to be occupied by a Dr. Gibson Burns, an African doctor. Because his homeland was so warm, he could never cool off, so he kept a glass of ice water in every room, earning the nickname "Freezer Burn." One day, he mysteriously disappeared. But, legend has it, at the beginning of every February, "you can hear the thump of feet and see the stick figure of a man jumping off a pier, screaming 'freezer.' "

Around 30 people show up to try to hear Dr. Burns and take the plunge each year, with several hundred spectators nearby.

The reasons people jump into freezing water are as varied as the participants themselves.

Lynne Cox, a California-based writer who has documented her record-breaking cold-water swims in the Arctic and Antarctic, said the swims leave her feeling "refreshed, invigorated ... and very alive."

Some claim swims in cold water have health benefits. In Finland, it's called Avantouinti, Finnish for "ice hole swimming," and practitioners claim it reduces stress and lowers blood pressure.

Jean Kern's husband, John, did the Pittsburgh Polar Bear Plunge every year from when he was a young man until his death in 1987, when he was 72. She said he claimed it was "like a shot of penicillin."

"He never got sick," she said, despite working construction jobs outdoors in the winters.

Jeanne Doperak, a doctor of sports medicine for UPMC, said there have been no proven health benefits for polar bear plunges or for ice swimming. But she warned there are risks that people should be aware of. She cautioned those with heart conditions, high blood pressure or hypertension.

"When you have a sudden immersion or cooling of the skin, you get an increase in heart rate and an increase in blood pressure," which could be dangerous for those with underlying conditions.

Opinions differ on the best way to do the plunge. At GALSA's event, organizers encourage participants to get down to their jumping gear -- whether it be swim trunks or a cow costume, as has been the case -- and hang out for 20 to 30 minutes before the jump to get acclimated as best as possible.

Kern said her husband made a half-gallon of what he called "Irish Tea" every New Year's morning. She didn't know its precise ingredients, but knew it contained tea and "spirits."

"It warmed up their insides after they got out of the water," she said.

Dr. Doperak advised against both, saying that alcohol "lowers inhibitions," and can make it difficult for people to gauge how cold they are and that hanging out in the cold without adequate clothing increases one's chances of "cold injury."

Cox looks to the animal experts to learn how to brave the cold. She employs what she described as the "polar bear paddle," meaning she propels herself by moving her legs and arms beneath her body to keep her head out of the water during the initial phases of a swim and then moves to an over-arm stroke.

Though participants might channel their inner polar bear, they certainly lack the equipment that allows the bears to survive swimming in 28-degree water. The bears' hair is water-resistant and underneath the coat their skin is black, which allows them to absorb heat. They also have a thick layer of fat to protect them from the elements.

Humans lack any of these mechanisms, the fat layer notwithstanding, which is why a long cool dip can be dangerous, said Dr. Doperak.

If you have to jump in freezing water, she recommends the following: show up sober, stay warm until the plunge, don't drink the water, and warm up immediately afterward.