To the south of Miami are the Florida Keys (from the Spanish cayo, "islet, reef"), a chain of coral islands of varying size which extends for more than 110 miles/180km between the Atlantic and the Gulf of Mexico. Until a devastating hurricane in 1935 they were linked by a rail line extending to Key West, from which there were boats to Havana (Cuba). The boldly engineered Overseas Highway (US 1) now runs over 42 bridges and numerous artificial causeways to the south-eastern tip of the United States. The little islands of Sands Key, Elliot Key, Cotton Key and Old Rhodes Key, lying off Biscayne Bay, are now part of the Biscayne National Underwater Park, established in 1980. Off Key Largo (pop.
11,000) are the John Pennekamp Coral Reef State Park and the Key Largo National Marine Sanctuary, the only living coral reef in the continental United States. The rich underwater life and a number of wrecks attract large numbers of snorkellers and scuba divers. Islamorada claims to be the "sport fishing capital of the world". On Grassy Key is the Dolphin Research Center, where the TV series "Flipper" was filmed. Marathon (pop. 10,000) is the second largest town on the Keys. The new Seven Miles Bridge (1982) leads to the Bahia Honda State Recreational Area, with a beautiful bathing beach. On Big Pine Key is the National Key Deer Refuge, home to the last few hundred of the shy, miniature (only 2ft/60cm high) roe-deer of the Keys.
In the early days, pirates used the Keys as a temporary base during their pillaging runs. However, much of this activity stopped after 1822 when the U.S. Navy began to patrol the waters and built a base in Key West.
The coral reef to the east of the Keys is the only one found in the continental United States. It played a large role in the area's early economic development. When ships crashed into the shallow reefs, locals would salvage the cargo and resell it. This practice, known as "wrecking", was one of the first industries to bring prosperity to the region. Other important regional economic ventures were sponge fishing and cigar manufacturing.