The morning light over Cairns is flat and bright when the Evolution slides away from Reef Fleet Terminal. Sea spray scores the air, gulls wheel and the boat’s diesel hum sets the day’s tempo; within 90 minutes the ocean changes from port grey to the green-blue of outer coral country. You’ll anchor at two outer reef sites — typically Saxon or Norman Reef for the first stop, then Hastings Reef — spending five hours in total on the reef between snorkelling, dives (if booked) and deck time. A 10-minute helicopter loop over the lagoon punctuates the day with a bird’s-eye view of ribbon reefs and plateaus that have been building coral for millennia.