Diamond Beach is an unincorporated community and census-designated place (CDP) located within Lower Township in Cape May County, in the U.S. state of New Jersey. The CDP, and all of Cape May County, is part of the Ocean City metropolitan statistical area, and is part of the Philadelphia-Wilmington-Camden, PA-NJ-DE-MD combined statistical area, also known as the Delaware Valley or Philadelphia metropolitan area. As of the United States 2020 Census, the CDP's population was 203, an increase of 67 from the 2010 census count of 136.

Lower Township is a township in Cape May County, in the U.S. state of New Jersey. The township, and all of Cape May County, is part of the Ocean City metropolitan statistical area, and is part of the Philadelphia-Wilmington-Camden, PA-NJ-DE-MD combined statistical area, also known as the Delaware Valley or Philadelphia metropolitan area. As of the 2020 United States census, the township's population was 22,057, a decrease of 809 (−3.5%) from the 2010 census count of 22,866, which in turn reflected a decrease of 79 (−0.3%) from the 22,945 counted in the 2000 census.