I've recently been told that on liveaboards on the GBR there are no divemasters leading the dive. Is this true? If so any comments on how hard it is to navigate around, and how many surprises you face diving the reef regarding current, direction, depth, air, etc. Also, how would you rate the diving on the GBR. Probably the vast majority of people I've talked to have found it disappointing. Does anyone have any recommendations on liveaboards out of Cairns, and any idea into whether you can get a discount on a boat pulling out of the dock at the last minute?