Brookhaven is located centrally on the geographic Long Island and extends from the North Shore to the South Shore. According to the United States Census Bureau, the town has a total area of 531.5 square miles (1,376.6 km2), of which 259.3 square miles (671.6 km2) is land and 272.2 square miles (705.1 km2 or 51.22%) is water. It is the largest town in New York in terms of total area. Excluding water, however, there are four towns in the state with more land area: Webb in Herkimer County, Long Lake in Hamilton County, Arietta in Hamilton County, and Ohio in Herkimer County.