Always wanted to go here;
It's called Ningaloo National Park in Western Australia. Apparently it has the worlds largest dugong population. It's also home to an abundance of fish (500 species), corals (300 species), molluscs (600 species) dolphins, manta rays, whale sharks and humpback whales.
And since it's a National Park only like 20 people are allowed in at once to protect the eco-system.