Lizard Island National Park, Queensland
Why it made our list: We can't specify one particular beach on this island because the whole damn place is pretty spectacular and, along with the neighboring isles, it boasts 24 powder-white beaches, any of which we'd be happy to die on. Seriously, we could easily name this article "Lizard Island's Best Beaches." Even better, they're all surrounded by the Great Barrier Reef -- the beauty of which will pretty much blow your mind every day.
Bonus: If you can’t afford the one swanky resort that sits on this island (only accessible by private charter, of course) you can camp in the national park at Watsons Bay. If the camp well runs dry, there's a spigot of fresh water behind the hotel bar that you can use. Just don't talk to the paying guests.