"I'm a diver and heard mixed things about the Great Barrier Reef. Is it a must dive location or is it just completely overrun with recreational divers?"
Answer from John:
"The farther you go out the Reef, the more pristine its character. Have a look at this video - remember, the Great Barrier Reef is 50 miles off-shore:Sailing the Great Barrier Reef - YouTube. The Great Barrier Reef is the world's largest living organism. Surely, that warrants your attention. Just choose your actual destination carefully; do good research. The Lonely Planet guidebook has good dive tips."