Coco Plum Island This 18-room private island resort stands out for being adults-only as well as all-inclusive. The latter programs include room, food, drinks, unlimited water sports, and a variety of tours, such as day trips to Mayan ruins, zip lining, and reef snorkeling, as well as birding trips to nearby Man-O-War Caye to see pelicans, brown Boobies, and Magnificent Frigate birds.