North Horn
North Horn is the northern tip of Osprey Reef, an isolated Coral Sea atoll about 200 km off the mainland, and is the best known site there. The mooring sits on a bommie in about 12 m, with an amphitheatre and a swim-through behind it; the reef wall falls almost vertically for about 20 m, slopes to about 40 m and then drops to more than 400 m. Current mainly comes from the south and east, so most of the dive goes into it. The best dive follows the western wall south at about 35 m rising gradually past gorgonias, soft corals and whips with many sharks around; Undersea Explorer ran a shark-feeding dive here (the McFadyen account is historical, check whether your operator still offers it). Located in the Coral Sea Marine Park (Australian Marine Parks); Parks Australia notes Osprey Reef is for experienced divers and is protected from fishing. Liveaboard guests need no personal permit (operators are authorised); confirm zoning and rules on the official Coral Sea maps.
Facts
- Region: Great Barrier Reef North
- Area: Osprey Reef & Coral Sea
- Depth: 5–40 m
- Level: advanced
- Current: moderate
- Type: wall, reef, drift
- Coordinates: -13.8014, 146.546
- Highlights: grey reef sharks, whitetip reef sharks, gorgonians, amphitheatre bommie, potato cod
- Tips: Osprey Reef is reachable only by liveaboard; the crossing is open ocean and can be cancelled by weather. Parks Australia describes visibility as 30 to 60 m and notes hammerheads aggregate in cooler months.