Mason Neck State Park is on a peninsula formed by Pohick Bay on the north, Belmont Bay on the south and the Potomac River on the east. Bald eagles roost in the park and fish waters surrounding the peninsula. The park also attracts several other migrating and non-migrating species of birds, including tundra swans, various species of ducks and great blue herons. One of the East Coast's largest heronries is here and in the adjacent wildlife refuge.
The park boasts several hundred acres of hardwood forests consisting of oaks, holly, hickory and other species of trees. In addition, several wetland areas are also found in Mason Neck. Land was purchased over the years from private landowners and the Nature Conservancy. The park opened in 1985 and connects with a 2,000-plus-acre National Wildlife Refuge.