Biscayne National Park is a U.S. National Park located in southern Florida, due east of Homestead. The park preserves Biscayne Bay, one of the top scuba diving areas in the United States. Ninety-five percent of the park is water. In addition, the shore of the bay is the location of an extensive mangrove forest. The park covers 207 mi² (700 km²). Elliott Key, the park's largest island, is considered the first of the true Florida Keys being formed from fossilized coral reef, i.e. Key Largo limestone. The islands farther north in the park are transitional islands of coral and sand.