ADDISON COUNTY — The ice on Lake Champlain was 14 inches thick and the wind chill was 35 degrees on the February day in 2003 when Lissa Gebo plunged into the water.

The Vergennes woman said she went in “full tilt — head under and everything,” but does not remember what it felt like.

“I short-circuited,” Gebo said. “The second year was warmer.”

Second year?

Yes, Gebo took the dip in the frigid waters of Lake Champlain on purpose, and she and hundreds of others have made it an annual event. It’s all for a good cause — to raise money to benefit Vermont Special Olympics.

The 11th annual Special Olympics Penguin Plunge, as the event is known, will take place at Burlington’s Lake Champlain Waterfront Park will take place this Saturday, Feb. 11, at 11 a.m. Many groups of intrepid Addison County residents have formed in anticipation of this event, which is as much audacious stunt as altruistic fund-raiser.

Each participant must raise a minimum of $175 per person in sponsorships from individuals and businesses in order to participate, and many raise more according to personal goals. The participants jump into Lake Champlain through, if need be, a hole cut in the ice.

The event has become so popular that organizers added two more plunges to the Special Olympics’ calendar this year — one last Saturday in Lake Paran, in North Bennington, and another on Sunday, Feb. 19, at 1 p.m. at Lake Memphremagog in Newport. In Newport, as part of the Winter Carnival, lighted ice castles are part of the festivity, and in Burlington, also Winter Carnival weekend, ice and snow sculptures will surround the swimming hole.

Newport’s second annual plunge last year saw 200 people enter the water. Last year in Burlington, more than 600 people braved the cold to raise over $260,000. A crowd of 2,000 is expected this year to witness about 800 “penguins” plunging.

The Little City Triple Dippers will be among those taking a dive. In fact, the team — consisting of Gebo, Peggy Parks, and Sarah Leach of Vergennes — committed to taking a dip at all three Penguin Plunges.

Gebo, who coaches high school basketball in Vergennes, “went to watch Sarah jump” in the 2003 Plunge when she found the excitement was so contagious that she had to jump in, as well.

“It’s a great cause,” she said.

Peter Funk, who owns CPC Vermont in Middlebury, agrees. He recognized the exceptional nature of a mentally handicapped woman who worked with him, cleaning the cafeteria and bathrooms.

“She knew everybody,” he said. “Everybody got a hug from her. She had no worries. She was 40 years old and not a single gray hair on her head. You could be having the crappiest day, and then you saw her and you had a great day. It made me think, why am I sweating the little stuff?”

She inspired him to go all out for a cause that would benefit her, and every year has brought in $1,000. His method is high-profile: He stands in a bathing suit with an umbrella by the traffic light on Court Street near Mary Hogan Elementary School for 45 minutes a day during the week leading up to the plunge. He attracts incredulous shouts, questions, and contributions to the cause. This is Funk’s fourth year enduring February’s capricious tempers. Watch for him on Friday between 2:45 and 4 p.m., or monitor his accumulations at www.firstgiving.com/peterfunk.

Saturday will be more than just the first jump into a frozen Lake Champlain for Cole Moyer of Shoreham, it will also be his 15th birthday. Moyer thought participating in the Penguin Plunge would be such a memorable way to celebrate his birthday that he asked his 18-year-old brother, Taylor, and three friends — Andrew Warren of Shoreham, Bryan Relyea of East Middlebury and Jack Gish of Middlebury — to  join him.

The quartet of Middlebury Union High School students set up individual Web pages to raise at least $200 apiece. Thread Connections of Middlebury loaned them tuxedos to wear for the promotional shots on the Web sites, which can be found by search for each individual’s names at www.firstgiving.com/vtso.

The Vermont Special Olympics, while a good cause, is not the only reason to undergo this ritual, and neither is the thrill. Alison Zimmer, a physical therapist at Porter Medical Center, researched the health benefits of the process and found that submerging in ice-cold water and immediately reheating one’s body was surprisingly beneficial for the circulatory system.

The shock of submersion causes blood vessels to dilate, which challenges the system and retains inner warmth. Other benefits, such as increased effectiveness of the immune system, “are more anecdotal than scientific, but in my experience I’ve found them to be true,” Zimmer said.

Zimmer, as part of the Holy Flocamole team, is plunging for the third year. The only negative she cites is the “ice cream headache.”

SPECTATORS WELCOME

Parking for spectators and participants is not available at the Burlington waterfront, but it is in city garages near the Church Street Marketplace. Mountain Transit Penguin Plunge shuttles will run from the corner of Church Street and Main Street to and from the event between 9 a.m. and 1 p.m.

“The people and excitement beforehand is really special,” Zimmer said. The groups gather in a staging tent where televisions relay the action on the waterfront. At each group’s designated time, members run through the crowd, down the boat ramp, jump in — some even swim out a ways — and wade back onto shore.

Bodies are steaming and salt is being thrown onto the dock to prevent freezing. Coast Guard divers are on hand for medical emergencies. The group runs back to the changing tents (one for men and one for women), where hot chocolate and coffee can be found amid heaters blowing warm air.

“It gives you kind of this warm feeling,” Gebo said. “You’re warm the rest of the day.”