Middle Island is a hamlet and census-designated place in the Town of Brookhaven, Suffolk County, New York, United States. The population was 10,483 at the 2010 census. It is situated between the hamlets of Coram and Ridge, to the west and east, respectively, and Rocky Point and Yaphank to the north and south. The name derives from the fact that it lies approximately halfway between the eastern and western ends of Long Island as well as halfway between the northern and southern boundaries.