North Horn (Osprey Reef)

The northern point of Osprey Reef, a submerged Coral Sea atoll about 350 km offshore from Cairns and reachable only by liveaboard. A coral shelf at 10–15 m steps down to a natural amphitheatre around 20 m, then the wall drops vertically into more than 1,000 m of open ocean. North Horn is built around its sharks: a controlled feed run here for decades has habituated 20–30 grey reef sharks plus whitetips and silvertips that circle within a few metres of seated divers, while scalloped hammerheads, manta rays and dwarf minke whales pass through in the cooler months. Visibility routinely tops 40 m over walls hung with gorgonians and Acropora gardens.