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Best Reefs for Diving in Cairns

Updated Tue 06 Sep 2022

The back of four divers over looking the coral sea

Australia’s Great Barrier Reef is made up of around 3000 individual reefs and is home to more than 9000 marine species, and naturally is home to the best scuba diving sports in the world. No two reefs are the same, with each being unique in its architecture and biodiversity. Some reefs — like Agincourt, Flynn, Milln, Norman and Saxon — are easily accessible by a short boat trip, others — like the Ribbon Reefs, Bougainville, Osprey and Cod Hole — are found further offshore and are better suited to liveaboard diving trips.

To make things easy for you, we’ve made a list of nine of the best Great Barrier Reef dive sites and what you’ll discover there. Dive in!

Day Boat Diving

Agincourt Reef

turtle in coral

Where: 65 kilometres offshore from Port Douglas, 90-minute journey

Reef Features: Garden reefs, shipwreck, swim-throughs 

Marine Life: Barracuda, Christmas tree worms, clownfish, cod, coral trout, drummers, feather starfish, fusiliers, giant clams, Goldman’s sweetlip, green sea turtles, grey tip reef sharks, hammerhead sharks, juvenile grey whalers, loggerhead turtles, mackerel, manta rays, parrotfish, Queensland groupers, trevally, triggerfish, tuna, unicorn fish, wrasse

With over 29 reefs making up Agincourt Reef, you’ll find some of the best scuba spots on the Great Barrier Reef here. Join the thoroughfare of marine life (juvenile grey whalers, manta rays, tropical fish) riding the currents through Harry’s Bommie, or play with the big boys (tuna, trevally, mackerel) out at The Chapel — which, as Great Barrier Reef legend has it, is named after a wedding that took place there long ago. You could even score an extra-exclusive one-on-one experience with a hammerhead shark out at Gary’s Gut, or explore the carcass of a Taiwanese ship at Wreck Reef.

Flynn Reef

coral underwater

Where: 60 kilometres offshore from Cairns, 30-minute journey

Reef Features: Canyons

Marine Life: Boulder coral, clownfish, giant clams, Maori wrasse, sea cucumbers, sea turtles, staghorn coral, triggerfish

Being only a half-hour cruise from Cairns and frequented by mild currents, Flynn Reef is perfect for novice divers and snorkelers. Explore depths between 5 and 30m, with visibility down to 20m. The oceanic residents of Flynn Reef are mighty houseproud and will always keep their home tidy for visitors: while the clownfish tend to the stinging arms of the sea anemones that sway in the current, the sea cucumbers vacuum the sandy beds. This is sure to keep the grandmother of the reef, the giant clam, happy. Giant clams can live for as long as a hundred years and weigh up to 200kg. Big mama. If you think that’s old, the giant boulder-shaped colonies of coral (boulder coral) at Flynn Reef can live for up to a thousand years!

Milln Reef

coral underwater

Where: 30 minutes offshore from Cairns

Reef Features: Coral bommies, coral walls, crevices, overhangs, swim-throughs

Marine Life: Banded sweetlip, nudibranchs, sea turtles, whitetip reef sharks

Perched on the outer edge of the Great Barrier Reef, Milln Reef is a relaxing 30-minute boat ride from Cairns. This is one of the best scuba spots on the Great Barrier Reef for novice divers thanks to its clear and shallow waters. Milln is made up of four smaller reefs: Whale Bommie, which is famous for its night diving; Pataj Mooring, full of swim-throughs, sea turtles and whitetip reef sharks; Three Sisters, named after the three coral bommies that rise from the ocean bed and teem with marine life; and Swimming Pools I and II, where you can watch the dazzling colours and patterns of the banded sweetlips and nudibranchs dance between the corals.

Norman Reef

turtle underwater

Where: 80 kilometres northeast of Cairns

Reef Features: Caves, shipwreck, swim-throughs

Marine Life: Angelfish, bronze whalers, clownfish, cuttlefish, drummers, dwarf minke whales, fusiliers, groupers, hawkbill turtles, nudibranchs, manta rays, Maori wrasse, moray eels, red bass, spangled emperors

Norman Reef is bursting with a rainbow of coral gardens and vibrant marinelife, and its next-to-perfect visibility provides photo opportunities in abundance. For the scuba divers, something extra special lies in Norman Reef’s depths, where caves, swim-throughs and even a shipwreck can be explored. Diver’s Den can hook you up with a gorgeous five-hour trip to Norman Reef and its neighbour, Saxon Reef.

Saxon Reef

coral underwater

Where: 55 kilometres northeast of Cairns 

Reef Features: Coral gardens (hard and soft corals), 

Marine Life: Clownfish, Maori wrasse, moray eels, painted crayfish, sea turtles, Spanish dancer flatworms, spot reef sharks, stingrays, whitetip reef sharks

Located between Norman and Hastings Reefs, Saxon is made up of shallower lagoon areas that teem with coral gardens and clownfish anemones. Its deeper drop-offs with steep coral walls descend to the sandy ocean floors, where you can spot reef sharks, stingrays and sea turtles that drift between the soft corals. Don’t forget to keep your eyes open for the Spanish dancer flatworms in the lagoon areas! The flatworms are nudibranch named after Spanish dancers for their bright speckled orange-red colouring, but they’re itsy bitsy so can be difficult to spy.

Liveaboard Diving

Bougainville Reef

divers sitting on the edge of the boat

Where: 212 kilometres from Cairns

Reef Features: Caves, gutters, ledges, shipwreck

Marine Life: Barracuda, bumphead parrotfish, grey reef sharks, silvertip sharks, trevally, tuna

Measuring just 4 kilometres in diameter, this little gem is nestled in the Northern Coral Sea and is considered one of the Great Barrier Reef’s more remote diving sites. Find yourself dancing with bumphead parrotfish and schools of small fish in the refractions of sunlight, which reach down to 40 metres. The great visibility also allows for viewings of the giant soft corals, red whip, wide gorgonian fans and black coral trees that climb all over the one-kilometre walls. There are also the remains of an Italian cargo shipwreck scattered across the corals of Bouganville.

Cod Hole

shark in coral underwater

Where: 96 kilometres north of Cairns

Reef Features: Calm and protected waters, coral bommies, 3 to 40-metre depths

Marine Life: Barracuda, coral trout, dwarf minke whales (winter months), flowery cod, giant clams, grey reef sharks, large Maori wrasse, lionfish, parrotfish, potato cod, pufferfish, pygmy seahorses, sweetlip, trevally

Cod Hole is located on Ribbon Reef Number 10 and is home to a family of big friendly giants, the — you guessed it — potato cod. These big fellas are goofy, beautiful and love getting up close and personal with divers. The potato cod isn’t the only BFG you’ll find spelunking these calm protected waters, there are also giant clams big enough to fit a whole human inside of them! But don’t worry, giant clams stick to a strict diet of plankton and, along with the other marine life you’ll find here, are relatively harmless. On the opposite side of the size spectrum, the depths of Cod Hole harbour teeny-tiny pygmy seahorses. These guys are so small (1.4 to 2.7 centimetres) that you’ll need your prescription scuba goggles to catch a glimpse! Enjoy all this Great Barrier Reef dive site has to offer on Mike Ball’s 3-day fly and dive tour.

Osprey Reef

Where: 350 kilometres northeast of Cairns

Reef Features: Caves, coral bommies, drop-offs, grottoes, overhangs draped in coral gardens, trenches

Marine Life: Glass sponges, great reef whaler sharks, green turtles, moray eels, octopi, potato cod, scalloped hammerhead sharks, sea lilies, sea-toads, silvertip sharks

Don’t let the distance of Osprey Reef deter you, in fact, its seclusion from the human world is what makes it one of the best Great Barrier Reef dive sites. Due to its sheer height (two kilometres!) Osprey is home to an expansive, varied, and let’s be honest, freaky ecosystem. There’s the sea-toad, which up until 2009, was thought to have only lived in South America. Or the ancient sea lilies and glass sponges, that once dominated the ocean. And, depending on how lucky you are, you might even spot the 500-million-year-old nautilus, so old it’s considered a living fossil. Soak up the wisdom from these ancient beings on the Spirit of Freedom’s four-day liveabord.

Ribbon Reefs

clam coral underwater

Where: 236 kilometres north of Cairns

Reef Features: Canyons, caves, channels, coral bommies,

Marine Life: Coral trout, barracudas, bluefin trevally, giant clams, large rays, minke whales, potato cod, scorpionfish, sweetlip, triggerfish, whitetip reef sharks

The Ribbon Reefs are long, thin reefs that run around 100 kilometres in length between Cooktown and Lizard Island, best explored by liveaboard trips. The reefs are made up of ten smaller reef systems, simply named Ribbon Reef Number One through to Ribbon Reef Number Ten. In fact, Cod Hole is situated within one of Ribbon Reef's smaller reefs. There’s so much to be explored here, especially for divers seeking a taste of waters untouched and rarely seen by humanity. With so much ground (or water) to cover, we recommend opting for a weeklong diving trip to see it all.

For more information on diving the best snorkel and scuba sites at Australia’s Great Barrier Reef, check out our deals for liveaboard tours and day tours departing from Cairns and Port Douglas. Our friendly support staff are always here to help you make your scuba dreams a reality!

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