Dendron Swamp Natural Area Preserve is a 636-acre (257 ha) 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 98 feet (30 m) tall line the river for two miles (3.2 km) 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.