Paddle along with the Potomac Riverkeeper and Chesapeake Conservancy, as guides provide a history lesson on the Ghost Fleet of Mallows Bay. The paddle (register by June 21) is part of the month-long RiverPalooza celebration, which is hosting paddling and adventure trips on the Potomac from Harpers Ferry to the Bay. 10:30 a.m.–3:30 p.m.

Nanjemoy, Md.; www.potomacriverkeepernetwork.org