The first undersea park in the U.S., John Pennekamp Coral Reef State Park encompasses approximately 70 nautical square miles. While the mangrove swamps and tropical hammocks in the park's upland areas offer visitors a unique experience, it is the coral reefs and their associated marine life that bring most visitors to the park. Many enjoy the view of the reef from a glass-bottom boat tour, but visitors can get a closer look by scuba diving or snorkeling.