If you're in Queensland, the Great Barrier Reef is a must. This catamaran trip from Cairns takes you to one of the reef's most idyllic islands, Green Island, and gives you the chance to spend the day as you please.
This ancient coral cay is home to an array of marine and birdlife. As a major sea turtle habitat, you just might meet one of the locals while snorkelling. If you prefer, relax on the island's white-sand beaches, explore the exotic jungle, or sip cocktails by the resort pool bar.