John Pennekamp Coral Reef State Park in Key Largo was the first undersea park in the United States, and it protects roughly 70,000 acres of coral reef, seagrass beds and mangrove shoreline. The waters here teem with colorful fish, corals and other marine life. Glass-bottom boat and snorkeling tours take visitors out to the reef, and the park also offers kayaking through mangroves, hiking trails and a campground. Divers and snorkelers can visit the famous underwater statue Christ of the Abyss. Entry is $8 per vehicle, plus tour fees. Book tours in advance during winter and spring, when demand is highest.