Kings Park is a hamlet and census-designated place (CDP) in the Town of Smithtown, Suffolk County, New York, United States, on Long Island. The population was 17,282 as of the 2010 census. It is bordered by Nissequogue to its east across the Nissequogue River, by Fort Salonga to its west, byCommack to its southwest, and by the hamlet of Smithtown to its southeast. Kings Park is noted for its fantastic schools, numerous parks, and natural beauty. Its tranquility prompted it to be the site of the Kings Park Psychiatric Center instead of New York City.According to the United States Census Bureau, the CDP has a total area of 6.6 square miles (17.1 km2), of which 6.2 square miles (16.1 km2) is land and 0.39 square miles (1.0 km2), or 5.93%, is water.