After several days in Sydney, we headed north for a bit of warmth and for a visit to the Great Barrier Reef, which Dwell follower @leedingtheway advised was not to be missed. We flew to Cairns and headed out for a day and a half on the reef snorkeling and diving. The dark patches in the water are sections of the reef close to the surface.  Search "great idea" from Touring Sydney, Part 2