The twin islands of Trinidad and Tobago are the Caribbean's odd couple. Trinidad is a densely populated, thriving island with a cosmopolitan population and strong regional influence. It's famous for hosting the loudest, wildest and most popular Carnival in the Caribbean. In contrast, 'little sister' Tobago is relaxed, slow-paced and largely undeveloped. There are claims that Daniel Defoe had Tobago in mind when he wrote Robinson Crusoe, and travelers who enjoy its beaches, reefs and birdlife still tend to think of the island as the last undiscovered gem in the Caribbean.