//metrognome logo// It was not a beautiful day for a swim. The temperature was just above freezing and the sky was a roiling gray, giving the mighty Atlantic Ocean that ice-green color that you see in boat disasters like "The Poseidon Adventure" or "The Perfect Storm." Yet here I was, standing on the beach at Coney Island in a thin Speedo, intent on jumping in. With the wind slicing me like an angry deliman slicing an undercooked ham, it was hard not to feel like a jackass (or, more accurately, a guy in "Jackass: The Movie"). But making a fool of myself was secondary to my higher scientific purpose: I had to know how they -- the members of the Polar Bear Club -- do it. How do grown men and women (not all of whom have my walrus-like protective layer of blubber) dive into near-freezing water? The club will begin its 100th anniversary of winter swimming with its annual New Year's Day swim on Wednesday. I've covered the swim for years, but this year, I wanted to cover it from the inside. Of course I had doubts. So many others before me had thought they could survive the swim only to turn into a quivering ball of goose-pimpled flesh. Last year, for example, Brooklyn Borough President Marty Markowitz kept a campaign promise to get in the water with the Polar Bears, but like so many politicians, he only kept part of his promise: his ankles. He was my first call. "The entire experience runs neck and neck with root canal," said Markowitz, who will return this year, this time promising NOT to swim. "My advice to you is: don't stop. Get to the water and run right in." Polar Bear Club president Ken Krisses and vice-president Luis Padilla handled my initiation. Both are longtime winter bathers who won't set foot on a beach if the thermometer reads more than 50. We met on the Boardwalk and walked to the churning surf -- me in my winter boots, them barefoot, walking over the snowy patches like they were goose down. I felt like a wimp. "This isn't a competition," Krisses reminded me. "It's not about how long you can stay in the water. It's not a macho thing." At the water's edge, we stripped down to our Speedos, the wind cutting like a near-sighted mohel. As per tradition, Krisses led us in a round of jumping jacks. "We say it's to get warmed up," Krisses said, "but it's really to make sure that if you're going to have a heart attack, you have it on the beach rather than in the water." And then we started the improbable walk towards the ocean. With Markowitz's words in my head, I never stopped, not even as the water passed my ankles, and then my knees and then that secret place that recoils like a Western pond turtle at the first hint of cold water. Krisses and Padilla dove in -- show offs! -- so I took the plunge, too. Because the body protects its core, I felt great -- even though my feet felt like two anvils being stored in an ice-cube factory. Breathing was the hardest thing, what with the Atlantic Ocean sitting on my chest like an 18-wheeler, but I was able to swim around for a couple of minutes. I left the ocean of my own volition, feeling invigorated and strong. And as you can see, this story isn't on the obits page, is it? --30-- gersh.kuntzman@verizon.net