Fun fact about the Swain's Lock Hiker-Biker Overnight Campsite--there's parking close by with space for approximately 8 vehicles. 

The walk to the sites is manageable and allows someone like myself, who prefers hiking miles in for some backcountry camping, to also appreciate the pleasures that come along with car camping. 

The sites are flat and dispersed with most located adjacent to the river (which you can't swim in--too dangerous). Each site comes with a picnic table, fire ring and grill. 

One thing to note, the sites are right off of the C&O tow path, which is busy during the day with runners, walkers, bikers, and other folks getting away from DC to enjoy the great outdoors.