Snorkelling/Scuba diving Outer Reef trips
There are so many dive and snorkel trips to choose from at Cairns, it was hard to choose, but but a helpful staff member at one of the backpackers helped us out by saying it's ok to go to places like Green Island if you're a simple day tripper, but to see really good coral, you must go on an outer reef trip as Green Island coral is now very badly damaged.
He also recommended a smaller boat, as he said getting suited up alongside 100 other people took ages, on full boats you wouldn't get such personalised service, and to be looked after (as I'm not really confident in deep water) it was better to have a smaller boat with less passengers. He recommended Cairns Reef Dive and we (and others we met later) found them really great
There were about 50 of us on the boat (some we dropped off on a floating overnight hotel boat out past Green Island) and there were about 7 staff members on board to help, set out the delicious lunch provided in the cost, etc. They were really organised in stowing all gear safely, making sure everybody was ok getting in and out of the water, giving advice, helping out, and as I'm prone to seasickness and was sick all the 2 hours out to the reef (and it was an unusually rough day too I think) they were very attentive and it just helped so much. They told me once I got into the water I'd be fine, and I was. Very friendly and informative captain too, you learn a lot about the reef while anchored and get about 3 hours to spend out there (time split between 2 different reefs) and so can get in and out of the water several times. You don't need to bring anything but your camera (underwater disposable as well is useful), towel and your swimmers, as everything else is provided at no extra charge.
We did bring our own face mask and snorkel from home, just because we were more familiar with the fit of them.