Florida Keys National Marine Sanctuary

View from space Sponge, coral, and searod. Courtesy: Florida Keys National Marine Sanctuary Staff 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. Covering much of the ocean floor are beds of seagrass that are of vital importance to the coral reef ecosystem. It is the largest known seagrass bed in the world.