Time Out says
Thousands of brave souls take a dip in the icy waters of Lake Michigan each winter, a feat that would seem crazy if the participants did it just for kicks. Thankfully, there's a very good reason for annual Polar Plunge: raising money for Special Olympics Chicago. Everyone jumps into the frigid lake is asked to raise $200 for the charity (though it's free to come out and watch the festivities on North Avenue Beach). In the past, celebrities like Lady Gaga and Vince Vaughn have shown up to join in on the chilly fun—who know which famous person you might spot this year?