People plunge into freezing Lake Michigan during Chicago Polar Bear Club 24th annual Polar Plunge event at Oak Street Beach on Jan. 25, 2025. The event was sold out after selling 1000 tickets. A person dunks into Lake Michigan after participating in Chicago Polar Bear Club’s 24th annual Polar Plunge at Oak Street Beach. (Audrey Richardson/Chicago Tribune) People come out of Lake Michigan after participating in Chicago Polar Bear Club’s 24th annual Polar Plunge at Oak Street Beach. (Audrey Richardson/Chicago Tribune) A person comes up for air after dunking into Lake Michigan after participating in Chicago Polar Bear Club’s 24th annual Polar Plunge at Oak Street Beach on Jan. 25, 2025. (Audrey Richardson/Chicago Tribune) People take photos and record as people make their way out of the frigid waters during Chicago Polar Bear Club’s 24th annual Polar Plunge. (Audrey Richardson/Chicago Tribune) A person idles in the freezing Lake Michigan temperatures during Chicago Polar Bear Club’s 24th annual Polar Plunge. (Audrey Richardson/Chicago Tribune) People plunge into Lake Michigan’s cold temperatures during Chicago Polar Bear Club’s 24th annual Polar Plunge at Oak Street Beach. (Audrey Richardson/Chicago Tribune) Katelyn Kellogg and Elizabeth Bowles, both from Louisville, Kentucky, pack on layers after participating in Chicago Polar Bear Club’s 24th annual Polar Plunge at Oak Street Beach on Jan. 25, 2025. Kellogg is in Chicago for her 25th birthday and wanted to participate as part of their trip. (Audrey Richardson/Chicago Tribune) People cheer before entering the water during Chicago Polar Bear Club’s 24th annual Polar Plunge at Oak Street Beach. (Audrey Richardson/Chicago Tribune) People embrace as they make their way out of Lake Michigan during Chicago Polar Bear Club’s 24th annual Polar Plunge on Jan. 25, 2025. (Audrey Richardson/Chicago Tribune) Founder of Chicago Polar Bear Club Brian Marchal makes an opening speech before the 24th annual Polar Plunge at Oak Street Beach on Jan. 25, 2025. (Audrey Richardson/Chicago Tribune)