Pigeon Swamp State Park is a 1,078-acre (436 ha) New Jersey state park located on Deans Rhode Hall Road (Middlesex CR-610) in South Brunswick, in Middlesex County, New Jersey, United States. It is an undeveloped park, with a mix of habitats including open ponds and uplands hardwood forests. It also includes a good example of an inner coastal plain lowland deciduous hardwood forest. At one time, it was a major nesting site for passenger pigeons before they became extinct. It was declared a National Natural Landmark in December 1976. The park is located in the Lawrence Brook watershed.