Pottery-shaped sponges, brown pelicans, mangroves, gentle manatees, turtles, ferocious crocodiles and brilliant butterflies are but a few of the species making their homes in Biscayne National Park, just across the Biscayne Bay but a world apart from downtown Miami. The waters of the bay hold secrets of natural and human history, from pirate wrecks to luminous coral reefs, while the land above encompasses four protected ecosystems, hundreds of species of wildlife and many historical landmarks.