External Territories
Diving in Coral Sea
Beyond the outer Great Barrier Reef the continental shelf drops away and a scatter of isolated oceanic reefs rises from 1,000 m or more of water. Osprey, Bougainville, Holmes, Flinders and Lihou reefs have vertical walls, 40 m-plus visibility, and shark populations that were never fished down. North Horn at Osprey is the best-known shark dive in Australia; the southern reefs are visited by a handful of boats a year.
THE LOCAL PLANNING BRIEF
Understand the options around Coral Sea
What this regional directory records Counts describe published records, not bookable trips or confirmed open sites.
There are 61 published site records in Coral Sea. The recorded categories include wall (27), reef (13), drift (7), pinnacle/bommie (7). These categories reflect the database; they are not a ranking, a conditions report or an assessment of your suitability.
Use the Coral Sea site cards to compare recorded access and depth, then open the individual pages for the map accuracy and source notes. Sites grouped in a region are not necessarily close enough to combine in one day.
Research operators in External Territories →Ask before booking
- Which territory and jurisdiction does this itinerary visit?
- What park or access permissions apply to the exact location?
- What is the contingency if transport changes?
Save the answers with the contact name and date. Separate confirmed arrangements from items still waiting for a reply.
Record your trip questions →Questions, answered
How do I choose a dive in Coral Sea?
Begin with the individual site and its source notes, then discuss the proposed trip with a local provider. The 61 published records are research options, not a list of trips available today. Match the plan to your training, recent experience and the operator’s current requirements.
When should I visit Coral Sea for diving?
Choose dates with a provider who runs the activity you want, then discuss seasonal patterns, recent conditions and alternative itineraries. A generic best-month claim cannot establish the conditions at your exact site or guarantee a wildlife encounter.
Can I use these maps to enter or navigate a dive site?
No. Recorded and approximate map positions support orientation only. Confirm the exact access, permissions, meeting point and route with the responsible local provider or manager.
Regional planning context: Parks Australia — Australian Marine Parks ↗. Directory counts come from published YouDive records. Individual site claims remain subject to their source and review notes.
Dive sites in this region
ReefCoral Sea
Saumarez Reef
A remote crescent reef with vast coral meadows, turtles and a Second World War Liberty ship wreck.
WallCoral Sea
Secret Caves (Osprey Reef)
Caves along Osprey's walls, especially good in the late afternoon and at night.
WallCoral Sea
Silver City (Osprey Reef)
Silvertip sharks, volcano-shaped bommies and caves on a slope that ends at a 1,000 m wall.
WallCoral Sea
The Abyss (Holmes Reef)
A dramatic drift along a 1,000 m wall cut with caves, gutters and canyons.
WallCoral Sea
The Castles (Osprey Reef)
Coral turrets, gullies and fan-filled overhangs above a 1,000 m wall.
WallCoral Sea
The Zoo (Bougainville Reef)
Bougainville's signature site, crowded with sharks, turtles and schooling reef fish in clear oceanic water.
Pinnacle/BommieCoral Sea
Turbo (Holmes Reef)
A lagoon pinnacle that comes alive with pelagic fish when the tide runs.
ReefCoral Sea
Turtle Cave (Holmes Reef)
Shallow bommies on sand at the Holmes overnight mooring – excellent visibility by day and a superb night dive.
WallCoral Sea
Walmart (Bougainville Reef)
A 700 m wall covered in colourful invertebrates and swarming basslets.
Pinnacle/BommieCoral Sea
Watanabe Bommie (Flinders Reef)
An office-block-sized pinnacle in open water, draped in soft corals and circled by pelagics and sharks.
WreckCoral Sea
Wreck Reef (HMS Porpoise and Cato wreck sites)
The 1803 wreck sites of Matthew Flinders' HMS Porpoise and the Cato, on a remote reef with outstanding visibility.
WreckCoral Sea
Wreck of the Atlas (Bougainville Reef)
A shallow, coral-covered 1945 freighter wreck spread across Bougainville's reef top and slope.
ReefCoral Sea
Cato Reef
A remote southern Coral Sea reef with giant bommies, flat reef at 10–15 m and 40 m-plus visibility.
Details need confirmationWallCoral Sea
Deep Six (Bougainville Reef)
A seldom-described Bougainville Reef site (marinelife.org.au's list of additional Bougainville sites and Mike Ball's itinerary…
Details need confirmationWallCoral Sea
Fan Fair (Flinders Reef)
A Flinders Reefs site on Mike Ball's Yongala & Coral Sea expedition, named for its sea fans.
Details need confirmationReefCoral Sea
Flora Reef
A tiny, rarely visited atoll with a sharp drop-off, silvertips and unusual lava-tube-like caves.
Details need confirmationIslandCoral Sea
Herald Cays
Some of Australia's most isolated reefs and cays, with nesting turtles, seabird colonies and the Coral Sea's last Pisonia forests.
Details need confirmationPinnacle/BommieCoral Sea
Leopard's Lair (Holmes Reef)
Numbers of leopard sharks resting on the sand around a coral pinnacle.
Details need confirmationReefCoral Sea
Lihou Reef
The Coral Sea's largest atoll – a vast, rarely visited lagoon with historic wrecks and untouched reef.
Details need confirmationDriftCoral Sea
Line of Sight (Holmes Reef)
A drift along the ridge in the channel between the two Holmes atolls.
Details need confirmationReefCoral Sea
Marion Reef
A vast, remote atoll with excellent soft-coral walls, lagoon pinnacles and three sand cays.
Details need confirmationReefCoral Sea
Mellish Reef
Australia's most remote Coral Sea reef, with a sheltered 12 m lagoon and seabird colonies.
Details need confirmationPinnacle/BommieCoral Sea
Mid Reef (Flinders Reef)
45 m bommies and a current-swept gully alive with feather stars, fans and soft corals.
Details need confirmationDriftCoral Sea
Middle Earth (Bougainville Reef)
A rarely described Bougainville drift site on Mike Ball's Far Northern expedition.
Details need confirmation