Well G6, about 20 years ago you could hire a yacht from firms at Airlie Beach and sail them yourself (or use the motor) in the Whitsunday Islands. Check it out now though. The snorkelling and diving were excellent at many spots. However, the reef might have deteriorated in some of them. If you have transport go up as far as Mossman and The Daintree River. In fact, go up as far as the road goes, there is an absolutely beautiful drive of about 20km, with the sea on your right and the jungle on the left (unless they've built on it), not far past the turnoff to Port Douglass. The road to there is also interesting, passing through km of a palm tree avenue. According to the stories circulating at the time, contractors would insist on payment to Christopher Skase before transporting & planting each one.
All this information is obviously out of date, but gives you some idea of what to google for.
