Ell Pond in Hopkinton, Rhode Island, is a kettle hole surrounded by red maple and Atlantic white cypress swamp and by steep granitic monadnocks, bringing sharply different plant communities into a small protected area. Its unusual mix of wetland and dry-ground habitats supports both hydrophytic and xeric plants, giving the site special scientific and educational value. Because the environment is fragile, trails run through the preserve but access to the pond itself is restricted. Protected land around the pond expanded in 1972 through purchases and existing holdings, and in May 1974 Ell Pond was designated a National Natural Landmark. As of 2025, it remains Rhode Island’s only listed site.