Plunge into the chilly waters at Sandy Point Park for the 17th annual Maryland State Police Polar Bear Plunge to benefit Special Olympics. Friday, businesses close up shop early to plunge as a group and enjoy a tailgate-style party. Saturday the pee-wees, pint-sized and families plunge early, with the two general plunges at 1pm and 3pm. Hear live music, compete in a costume contest and raise money for a good cause. F at 3pm; Sa 10am-5pm at Sandy Point State Park beach, Annapolis. $50/plungers; $500/companies; rsvp: 410-424-1515 x103; www.plungemd.com.