Looking for a fall fun run? This September race, which starts at Lake Needwood in Rock Creek Regional Park, winds through 29 miles of Rockville, Bethesda and Chevy Chase and isn’t a marathon, though it sounds like one. The Rock the Creek Relay is a team race consisting of six legs that take four or five hours to complete. Teams of three or six runners hand off the baton and meet again at Lake Needwood for the post-run party.