Fire Island is the large center island of the outer barrier islands parallel to the south shore of Long Island, New York. In 2012, Hurricane Sandy once again divided Fire Island into two islands. Together, these two islands are approximately 31 miles (50 km) long and vary between 520 and 1,310 feet (160 and 400 m) wide. Fire Island is part of Suffolk County. It lies within the towns of Babylon, Islip, and Brookhaven, containing two villages and a number of hamlets. All parts of the island not within village limits are part of the Fire Island census-designated place (CDP), which had a permanent population of 292 at the 2010 census, though that expands to thousands of residents and tourists during the summer months.
The land area of Fire Island is 9.6 square miles (24.9 square kilometres).
Fire Island lies an average of 3.9 miles (6.2 kilometres) off the south shore of Long Island, but nearly touches it along the east end. It is separated from Long Island by Great South Bay, which spans interconnected bays along Long Island: Patchogue Bay, Bellport Bay, Narrow Bay, and Moriches Bay. The island is accessible by automobile near each end: via Robert Moses Causeway on its western end, and by William Floyd Parkway (Suffolk County Road 46) near its eastern end. Cross-bay ferries connect to over 10 points in between. Motor vehicles are not permitted on the rest of the island, except for utility, construction and emergency access and with limited beach-driving permits in winter. The island and its resort towns are accessible by boat, seaplane and a number of ferries, which depart from Bay Shore (Fire Island Ferries), Sayville, and Patchogue.