When your ship docks in Cairns, take a shore excursion to idyllic Green Island and spend a day in a tropical paradise on the Great Barrier Reef. With four hours on Green Island you'll have plenty of time to snorkel, take a tour of the reef in a glass-bottom boat and explore the island. Enjoy the hour-long cruise to and from Cairns by catamaran, and experience the beauty of the Great Barrier Reef.