You could be forgiven for assuming from the other posts that only Australians would visit Great Barrier Reef, but that´s not quite true :-)
I´m not much of a sailing/diving enthusiast, but I did do a boattrip from Cairns to the Reef with some snorkeling, and I must admit it was really fantastic. You could see lots and lots of the most bizarre and colorful fish and corals, as well as big sea turtles, all in an evidently unharmed environment, despite the danger that global warming poses to this great site. If I decide to learn to dive, I´d probably come back here.