​FLORIDA KEYS, or REEFS, in Florida, a chain of small islands, keys or reefs, and sandbanks, extending S. W. from Cape Florida, about 220 miles. They are very considerable in number, but only a few are of any importance. Among these may be mentioned Cayo Largo, Indian Key, Long island, Old and New Matacombs, Cayo de Boca, and Key West, on which the city of Key West is built.