caymaniac:....Check out liveaboards like Taka, Mike Ball and Spirit of Freedom.
dmblack58:One thing to do before you head out diving is to go and see Paddy's Reef Teach presentation in Cairns.
Two good pieces of advice here ! Taka would be my choice of liveaboard. I used to work in Cairns, and the reef where the day boats go to is not too healthy. Liveaboards tend to go a bit further, and it's healthier out there. Taka goes to the Cod Hole on a 3 or 4 day trip I think. Definately go see Paddy too - a very entertaining and informative night - get there early too, late comers will miss the tim-tams !!