Preserve, southeastern Florida, U.S. Located 20 mi (32 km) south of Miami , with an area of 172,925 acres (70,035 hectares), it consists mostly of coral reef and water containing some 33 keys that form a north-to-south chain separating Biscayne Bay from the Atlantic Ocean.
It is noted for a wide variety of sea life. Authorized as Biscayne National Monument in 1968, it became a national park in 1980.