The main part of the reef and many of the best dive sites are a long way from the mainland. The best way to see the Great Barrier Reef is on a liveaboard. The most famous spot here is Cod Hole on Ribbon Reef. Ribbon Reef can be dived from a 3 or 4 night liveaboard trip. Osprey reef will take a week or so. The diving here is incredible and you can see lots of sharks. Cairns has heaps of dive ce ..