Everglades National Park is a national park in the U.S. state of Florida that protects the southern 20 percent of the original Everglades. In the United States, it is the largest subtropical wilderness. The Everglades are a network of wetlands and forests fed by a river flowing .25 miles (0.40 km) per day out of Lake Okeechobee, southwest into Florida Bay. The Park is the most significant breeding ground for tropical wading birds in North America, contains the largest mangrove ecosystem in the western hemisphere, is home to 36 threatened or protected species including the Florida panther, the American crocodile, and the West Indian manatee, and supports 350 species of birds, 300 species of fresh and saltwater fish, 40 species of mammals, and 50 species of reptiles.