Lady Elliot Island, Great Barrier Reef, Australia
Lady Elliot Island is a very small coral cay about 50+ km off the Queensland coast. The island itself is tiny, and can easily be walked around in less than an hour. There is only one resort on the island, a self-proclaimed 'low-key' eco resort, which is a good description - the people are great, and the accommodation is all that's required, but it's the diving/snorkelling you go there for!
Lady Elliot Island is probably best known for being one of the best places to see and dive with Manta Rays in Australia. I had three dives there last week, and probably spent over 20 minutes in total just watching mantas sit over a few coral bommie 'cleaning stations' - fantastic! Visibility was about 20m.
There is also a more sheltered lagoon area, which is great for newer snorkellers, kids etc, and the marine life there is fantastic too - i.e. five or so green turtles and a couple of black tip reef sharks in the last 15 minute snorkel before I left.
Be aware that the island is used by thousands of birds year around (great for photography topside!), but some people found the smell pretty strong - I reckon you get used to it quickly..
Food was really good - buffet breakfast and dinner are included with accommodation, and you can pay for cafe meal or buffet for lunch.