The Florida Keys National Marine Sanctuary is a U.S. National Marine Sanctuary in the Florida Keys. It includes the Florida Reef, the only barrier coral reef in North America and the third-largest coral barrier reef in the world. It also has extensive mangrove forest and seagrass fields. The marine sanctuary includes a 2,800 square nautical mile (9,600 km²) area surrounding the Keys and reaching into the Atlantic Ocean, Florida Bay and the Gulf of Mexico. The sanctuary was established in 1990.