Take a chilly dip into the Peconic Bay on Dec. 9 at the Riverhead Recreation Department’s Polar Plunge: Freezin’ for a Reason event at South Jamesport Beach. Warm drinks, light refreshments, and music will set the scene for a winter swim to raise money for a charity of the swimmer’s choice. Beach towels will be gifted to the first 50 registrants. The event, open to all ages, takes place from 10 a.m. to 12 noon. For more information and to register, visit the Riverhead Recreation Department’s website.