The Coral Sea sites are isolated vertically walled reefs some distance out from the main structure, and require a three-day trip or longer. They are surrounded by open water teeming with seasonal bundles of pelagic species including mantas, turtles and seasonal minke whales. The most-visited Coral Sea sites are Osprey and Holmes reefs, but try to get out to Bougainville Reef, home to everything from brightly coloured anthias fish to fast and powerful silvertip sharks.