Hey Marcy,
I just joined the board today! Anyway, I just got back from Australia two days ago. I was there backpacking for a month and it's amazing... everyone there is super nice. When I was there I dove the S.S. Yongala. The Yongala is amazing because all the sea life there looks as if they took steriods (honestly it's ridiculous). You can take a charter there from Townsville, Magnetic Island (lots of fun there), or Cairns. I also did a 2 day/1 night trip with Reef Encounter. Reef Experience is their day trip counterpart, but if you want to stay on the reef for a night or more look at Reef Encounter. The rooms are nice, the food is good, and the crew is freakin' fantastic! Also, I didn't do it myself, but I heard diving the Julien Rocks off of Bryon Bay is a wonderful dive as well. Let me know if you have any other questions about Australia, diving or not, I'd love to help. Have fun, I know you will, Cheers Mate!