Fire Island is a barrier island, approximately 31 miles (49.5 km) long and varying between approximately 0.1 mile (0.16 km) to 0.5 mile (0.8 km) wide, in Suffolk County on the southern side of Long Island in the U.S. state of New York, running approximately WSW to ENE. The land area is 48 km² (18.7 sq mi) and a permanent population of 310 persons was reported as of the 2000 census. (There are many thousands of seasonal residents.)