Marathon is a city in the Florida Keys. It’s set on 13 islands, known for their beaches and barrier reef. Loggerhead turtles nest at Coco Plum Beach and Sombrero Beach. Curry Hammock State Park has a sandy shoreline and mangrove creek. The Dolphin Research Center offers interactive demos in a shallow lagoon. Near the City Marina, Crane Point features a tropical forest, bird-rescue center and natural history museum.