Two- and four-legged plungers leap into the South River in the third annual Puppy Plunge to benefit Anne Arundel County’s Society for Prevention of Cruelty to Animals. Pups also compete in a bikini and best trick and pooch smooch contests and, new this year, a puppy pie-eating contest. Plus, hear live music by The Oyster Boys and see demonstrations; refreshments sold. Noon-4pm at Camp Letts, Edgewater. $5: 410-268-4388; www.aacspca.org.