Harpers Ferry, West Virginia Drive time from DC: One hour and 15 minutes. The current summer mantra: maximum cooling, minimal exertion. To embody this philosophy, plop yourself in a tube near Harpers Ferry, West Virginia, and take a ride on nature’s lazy river. Outdoor adventure groups River Riders and River and Trail Outfitters run tubing trips ($33 to $44) on gentle sections of the Shenandoah River. (Whitewater options are also available.) Fl…