With just four French Colonial villas strewn alongside a half-mile-long stretch of private sand, Cousine feels like one of the most exclusive spots on earth. But from the moment it was transformed from a rat-plagued coconut palm plantation to a private nature reserve, the property’s real VIP’s have been its hawksbill turtles, wedge-tailed shearwaters, sooty terns, and other assorted animals. In fact, the resort’s entire raison d’être is to fund the island’s conservation efforts—which means minimizing waste and maximizing efficiency is a priority. Rainwater is collected and treated for drinking, solar panels create energy for heating, and water meters in the rooms allow guests to monitor what they’re consuming. Heady stuff for a haute holiday.