Trial by ice

Terrence J. Sheahan wants you to remember one thing about the polar plunge.

“This is going to a good cause.”

That was the phrase running through Sheahan’s head the first time he stood at the precipice of Lake Michigan in a pair of sweatpants and a T-shirt in the dead of winter and prepared to dive into the barely unfrozen lake to raise money for the Chicago Special Olympics.

Sheahan, a partner at Freeborn & Peters LLP, doesn’t remember what year he first did the plunge, but he estimates it was nearly 10 years ago.

Ten years later, he’s still diving. That’s another thing he wants you to remember: People love it enough to return.

“Each year it gets bigger,” he said. “The first time I jumped there were a couple hundred people. This year they expect at least 2,500.”

See? If you decide to join Sheahan and about 20 other Freeborn attorneys, you will be in good company. The 14th annual Polar Plunge is Sunday morning at North Avenue beach.

It’s a simple operation. Divers run down a chute that has been placed on the beach, they slide into the water and they run back to a tent and the comfort of dry clothes, music, adult beverages and, if needed, a trained staff of emergency personnel.

The Freeborn attorneys are one of two teams of Chicago attorneys joining the annual charity event — some of their peers at Ungaretti & Harris LLP will be out there, too. All told, Sheahan estimates that there will be at least 50 attorneys participating.

He is hoping he can convince even more Chicago attorneys to join the teams at Freeborn and Ungaretti & Harris. If he’s lucky, they will be as easy to convince as his 12-year-old daughter, Eileen.

“She’s come down before and watched me participate, and I told her when she reached the age of 12 she could do it with me,” Sheahan said. “She’s holding me to that promise.”

Speaking of holding people to plunge-related promises, Mayor Rahm Emanuel is doing the plunge on account of the promise he made to Chicago schoolchildren, whereby he would do it if they read a total of 2 million books.

And late-night talk-show host Jimmy Fallon is doing the plunge on account of the promise he made to Emanuel to do it in exchange for the mayor doing “The Tonight Show.”

Some might deride the Emanuel-Fallon plunge as a publicity stunt, but to people like Sheahan committed to raising their monetary goal, their participation is a gift.

“We were very pleased to hear that the mayor is participating, and when he challenged Jimmy Fallon and he took the challenge, we were thrilled,” Sheahan said. “We hope that’s just one more reason for people to come down and participate in the event.”

The plunge is the largest annual fundraiser for the Chicago Special Olympics. Event organizers hope that the celebrity draw will help them reach their target goal of $1 million.

Sheahan hopes so, too. And if you’re still on the fence, he also wants to remind you that the temperature should be a “balmy” 15 degrees.

“I don’t believe it’s going to be any colder than it was several years ago,” he said. “They had to get a bulldozer to clear out the chute and break up the ice to jump in.”

The beach was covered in snowdrifts that day while the lake was filled with floating chunks of ice.

But no matter. Sheahan said that participants ultimately view the plunge as a “bucket list” item. The event attracts all ages: Sheahan has seen divers as young as 12 and as old as 80.

It’s festive, too. People dress up in costumes, there is music and, most of all, there are groups of friendly people supporting each other all in the name of charity. Anyone looking to donate can go to sochicago.org/chicago-polar-plunge and support Sheahan’s team at firstgiving.com/team/258235.

“It’s a wonderful day,” he said. “It’s to me the end of the winter and the beginning of spring. And the environment is really dynamic. You have several thousand people doing an otherwise hazardous activity in the name of a charity.”

So there you go. An event in which you can help raise potentially $1 million for Special Olympics, meet Fallon, land on national television and welcome the coming spring.

If you’re still not sure, Sheahan wants to remind you that no one stays in the water for more than 10 to 15 seconds.

“You’re really only cold for a few minutes,” Sheahan explained. “Some people just go in up to their knees. But to each his own.”