He won't be alone.
If the past is any indication, at least 1,000 people will be with him during the Hilton Head Polar Bear Plunge at Coligny Beach.
Guest, a New England transplant who started the event a decade ago, expects at least that many swimmers after the 2012 swim was canceled.
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"There is no cost. It's just fun," said Guest, who owns Island Spirits & Fine Wines.
"We get a lot of people and just have a nice time," he said, noting that the Portuguese man of war jellyfish that sank last year's event have not shown up this year.
Two hours later and about 20 miles away by boat, the Friends of Hunting Island will host the Pelican Plunge at Hunting Island State Park.
The 1 p.m. event raises money for the Discover Carolina program, which helps local students in third, fifth and seventh grades visit the park for a day of learning. Organizers hope to draw 1,500 swimmers and spectators and raise about $5,000.
"It's a fun event and a great way to start the new year and shake off the after-effects of the previous night," said Dick Geier, president of the Friends of Hunting Island.
Since it began in 2009, the plunge has grown from about 50 swimmers to more than 400 last year. It now features a costume contest, a large-scale Simon-says game, bonfire and kazoo rendition of the national anthem.
Although the event is free, participants are urged to make a donation or seek pledges from friends and family, said organizer Bruce Doneff.
The Hilton Head event, now in its ninth year, also has grown significantly since it started.
Guest recalls early events when he could walk among the swimmers, letting them know when to get ready and when to dart toward the water. Now, he uses hand signals rather than trying to shout over the crowd.
After they leave the water, swimmers can grab cookies or hot chocolate provided by Lynn and Dana Cortes, owners of the Atlanta Bread Co. restaurant on Pembroke Drive.
Ocean temperatures average about 55 degrees in early January, organizers say -- about 30 degrees lower than during the summer.
Still, Geier and other veteran plungers say it's not as bad as it sounds.
"It's not like breaking through the ice like they do up North, which is absolutely insane," he said.
Diving in, he added, is optional.
"You can go in, splash around, sit down in it and get out."
Follow reporter Casey Conley at twitter.com/IPBG_Casey.
http://www.islandpacket.com/2008/12/26/707403/five-minutes-with-tim-gues... " target="_blank">Five minutes with: Tim Guest, organizer of the Polar Bear Plunge, Dec. 26, 2008