Plunge into the chilly waters at Sandy Point State Park for the 19th Annual Maryland State Police Polar Bear Plunge to benefit Special Olympics. Pee Wees and families plunge early (11am), with two general plunges at 1pm and 3pm. Hear live music, compete in a costume contest and raise money for a good cause. Park opens 8am. $75; rsvp: www.plungemd.com.