The Potomac is the longest and most diverse river system in Maryland, reaching from the cold, high plateau of the Alleghenys to the broad waters of the Chesapeake Bay and tidewater. From the start to Great Cacapon, West Virginia, the atmosphere is mostly wild and the scenery is dominated by beautiful Sideling Hill and Cacapon Mountain. Below Great Cacapon the mountain views continue to be pretty, but the riversides become filled with summer homes. The river flows swiftly over a rocky bottom with occasional riffles formed by tiny ledges. Watch for one strong riffle through the ruins of the old C&O Canal Dam No. 6.