The Overseas Highway, the portion of U.S. Route 1 between mainland Florida and Key West, is one of the country’s most iconic drives. The 113-mile series of roads and causeways threading the Keys (“Key” comes from the Spanish word for small island, cayo) passes by mangroves, tropical forests, yacht-filled marinas, fishing-boat-lined piers, plush resorts, faded motels, modern strip malls and charming old seafood shacks. The highway’s view routinely opens onto the shallow islet-dotted sea surrounding the Keys, its bottom of white sand, coral reef and turtle grass flats creating a spectacular patchwork of blues ranging from deep lapis to almost iridescent turquoise. Causeways sometimes extend for miles between islands, and driving along them can be exhilarating — especially in a convertible.