Dendron Swamp Natural Area Preserve is a 636 acre Natural Area Preserve in Sussex County, Virginia, USA. Located along the Blackwater River, the preserve supports a bald cypress and tupelo swamp. Canopy trees over 30 m tall line the river for 2 mi and the swamp shows only occasional signs of logging. Some of the larger cypresses are believed to be over 600 years old. Within the preserve is a nesting site for the great blue heron. The preserve contains the Charles C. Steirly Natural Area, a 19 acre swamp containing an essentially virgin forest of bald cypress and water tupelo that was designated as a National Natural Landmark in 1974. The preserve does not have facilities for public access and visitors must make arrangements with the Virginia Department of Conservation and Recreation before visiting.