Called "La Perla del Oriente" or "La Cuidad Gris" (gray city), Humacao was founded in 1722. Derives its name from a local Indian chief Jumacao.
Off shore near (1 km) Humacao is an island inhabited by Rhesus monkeys once used for scientific experiments back in the 1930s. Cayo Santiago (15.2 ha (38 acres) host one of two field stations of the Caribbean Primate Research Center in the island. The small island contains a population of approximately 800 monkeys, which are direct descendants of the original 409 monkeys imported from India and released onto the island in 1938. Research policy strictly limits the number of visitors allowed on the island at any one time, but you can cruise around it and snorkel nearby, observing the monkeys from a distance that is safe for both you and the animals.