>Dive Destinations>Australia>Cairns' Outer Barrier Reef

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• Reef summary
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...Highlights: turtles, great macro life/ marine diversity...
...Diving environment: wall diving, beginners, very popular...

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Starting at a distance of 50 km off shore and forming the further reaches of the Great Barrier Reef Marine Park, the Cairns Barrier Reef offers wall diving, swim throughs and endless fields of corals in clear blue waters, all accessed only by the Cairns liveaboards that frequent this area.

What is sometimes called the Outer Barrier Reef is a must if you fancy doing some nice and easy, entry level scuba diving off Cairns. This area includes the reefs on Milln, Flynn, Thetford, Hastings, Briggs, Norman and Saxon. All of the low budget liveaboards that we recommend visit the Outer Barrier Reef.

The reef attracts a multitude of marine life and interesting critters. Turtles, white tip reef sharks, groupers and large wrasse are abundant, and in some areas even dolphins and bronze whalers are nothing unusual.

Coral bommies interspersed with sandy gullies and staghorn thickets make up the typical landscape of the barrier reef and the Cairns sites feature excellent positions from which to observe the daily life of marine cratures on the reef. Surprises from the blue are also common with schooling fish action an ever-present constant.

The Inner Barrier Reef consists of shallow reefs accessible through shore dives from the islands or day trips. We do not offer that area since the quality of the diving isn't as high as the Cairns Outer Barrier Reef or further offshore on the Great Barrier Reef proper.

Dive Site Descriptions

Flynn Reef

60 km east of Cairns, Flynn Reef has excellent wall dives and a wide-ranging scuba experience, with swimthroughs, over hangs, expansive fields of hard corals and an abundance of diverse marine life. It is home to several turtles and with some diver's luck you will see them all. One of them is truly enormous and must have lived the good life, and a long one too, to have reached such a size.
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The colour on Flynn Reef is courtesy of the hard coral field, which features staghorn, table, plate and boulder coral heads. Splashes of vivid blue, green and yellow is interjected by many species of soft corals that can be found in Cairns. Luckily on Flynn Reef there is always something willing to provide you with a photo opportunity. As you drop down the reef to the slightly deeper sections, you can catch sight of white tip reef sharks that are frequently sighted in Cairns. At night they hang out in shallower areas resting in the small caves and overhangs of the bommies.

Before diving Tracy's at Flynn Reef the first thing to appreciate is the arc of beautiful aquamarine water that surrounds the dive boat. You will feel like you are in one of those glorious promotional images of the Great Barrier Reef featuring a large white liveaboard sitting atop crystalline waters of varying shades of blue and illuminated by bright, sunny skies. Below the surface is also pleasing on the eye as this site features ever-changing topography. The fine white-sand sea-bed is dotted with little bommies and coral outcrops which can be investigated as a separate shallow dive. Adjacent to this area is a larger reef section which rises from around 25 metres at its deepest to just a few metres below the surface.

Beginners will delight in "finding Nemo" on one of the bommies where a few 'true' anemones live with an entire neighbourhood of playful anemone fish. Extremely photogenic, but notoriously hard to capture, these little "Nemo's" seem to know just when you are about to press the shutter release on the camera and change their pose. There is also a good chance of spotting giant moray eels and the elusive wobbegong often seen on the indented shelf beneath a large stone coral bommie.

Elsewhere on this dive you can enjoy exploring the ruts and overhangs of the main reef. At some sections the overhang blocks out so much light it can be eerie. All around the reef are shelves, crevices and tunnels although there is nothing wide enough to be called a proper swim-through. There are however, quite a lot of fish on this section of the reef including large schools of fusiliers as well as oriental sweetlips, parrotfish, goatfish and other small-to-medium reef inhabitants like surgeonfish and rabbitfish.

Topographically this is one of the more interesting sites you will visit on standard Cairns diving cruises and, since it offers plenty of scope for investigation, it should please even more experienced scuba divers in the group. It is a great site for beginners with a lot of interesting features and some exciting marine life.

Boulders is 2 sites in one. You will probably do at least 2 dives here during your liveaboard safari, most likely this will mean firstly drifting along a wall and secondly exploring the shallows. The descent to both is down the same line to concrete mooring boulders which lie at a depth of less than 10 metres.

Turning towards deeper water, you will find a sloping wall along which there will often be a current running. The wall, as with much of the flatter section of the reef, features many hard corals including stony, mushroom and fire corals. Soft corals, hydroids and anemones are also present. Around the wall you will see several species of smaller reef fish such as butterflyfish, damsels and goldstripe wrasses. In the blue you may be able to spot larger fish and pelagics. Keep an eye out for trevally, Napoleon wrasse and whitetip reef sharks coming in from the blue.

In the shallower sections you can enjoy various sandy channels running in between sections of the reef which sometimes rise into the shallows. Here again the coral coverage is healthy as evidenced by the presence of giant clams. Perhaps it's something in the the water around Flynn Reef, because the giant clams can be enormous. To grow up to their sizes, which are up to 2m, the giant clams need to be well over 100 years old, putting things into perspective as you dive the Great Barrier Reef.

Fish-life enjoying the shallow sun-drenched waters, includes fire dart gobies, longnose filefish and fairy basslets. There are also anemones dotted around the shallows and it is worth spending a minute or two to check out their inhabitants. You might find Barrier Reef anemonefish (Amphiprion akindynos), endemic to the region, which are defined by their 2 thin white vertical bars. Another species is the orangefin anemonefish (Amphiprion chrysopterus), unmistakable with its bluey-white vertical bars and orange lateral fin against a darker body.

Also worthy of note are the frequency and variation of sea cucumbers to be found creeping across the sandy floor. Eyed sea cucumber, Graeff's sea cucumber and pineapple sea cucumber are all common. This is a site that normally enjoys good light and more fish than some of the other diving spots in the Cairns area.

Milln Reef

White tip reef sharks skirting along the edges of the reef, turtles resting under overhangs, coral trout and peacock groupers, are just some of the abundant marine life action that you will encounter on Milln Reef, 55 km east of Cairns. The reef is also favoured by dolphins, often seen around arriving or departing boats.
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Consisting of a few large bommies, rising from the sandy bottom at 30m to within a few metres of the surface, Milln Reef attracts a dazzling array of marine life. The reef is carpeted with colourful hard and soft corals, with gorgonian fans flaring in between. The deeper side of the largest bommie has brilliantly coloured black coral, home to commensal gobies, which are visible upon closer inspection. Additional rewards are to be had by the observant diver who will discover the reef's smaller critters, including nudibranchs, eels, sea stars and flatworms.

Striding in off the dive platform at Wildside, you will follow a fixed line down to concrete mooring blocks resting on the sea-bed at a depth around 12 metres. Surface conditions, particularly outside of the main high season can be choppy, so you would be advised to limit your time at the surface and proceed to the more sedate underwater environment of the reef itself.

From the concrete blocks the normal dive plan is to proceed with the gentle sloping reef to your right shoulder. This is likely to be your first sight of Cairns' Great Barrier Reef and you will be impressed by the health and vibrancy of the slope. The seascape is bedecked in had and soft corals including leather corals, whip corals and numerous but small table corals and other staghorns. The reef undulates gently and features a few sandy passages where you will see several species of sea cucumber, mushroom corals and occasional nudibranchs. Fish life is dominated by small fish and juveniles such as barracuda. You can expect to see some parrotfish, bird wrasses, butterflyfish and small surgeonfish.

As one of the early dives you will make on standard trips out of Cairns, your depth will probably not exceed 15-16 metres and it represent a good opportunity to make sure all your equipment is in order and to banish yourself of any scuba rustiness.

Around The Bend at Milln Reef is so called since the reef forms an arc that you will follow around with the slope on your right shoulder. This is another site that begins with a descent down a fixed line to concrete mooring blocks resting on the sandy seabed. As with other dives on Milln Reef, you will be struck by the health and cleanliness of the coral slope with several different types of hard and soft corals covering almost every available inch of substrate.

The topography here is the most interesting aspect you will notice, since the reef rises and drops giving way to sandy channels, and features small pinnacles and little bommies. Your dive will involve a slow steady exploration of the reef looking out for nudibranchs on the sea floor, butterflyfish and angelfish darting around the fissures on the reef and cleaner wrasse looking for their next snack.

On your ascent be sure to keep an eye out in the blue as you get to within a few metres of the surface. You may spot schools of small reef squid seemingly enjoying the surge. They are black in colour and no more than 10 cm in length but they are the creature you are most likely to see most of as they seem to congregate in schools of 20 or more.

3 bommies called Three Sisters also make up part of Milln Reef. 2 of the sisters are only a few metres apart with straight sided walls facing each other, creating a 2-3m wide mini canyon. The canyon is usually filled with colourful schools of fusiliers and snappers, with huge schools of tiny glassfish that seem to ripple out before you, synchronised with your movements. The canyon is also home to gorgonian fans and, if you check out the smaller corners and the base of the bommies, quite often you will find painted lobsters.

Milln Reef is an excellent spot for night diving, with the colourful soft corals that are seemingly more vibrant under the light of your torch, and the base of the bommies become perfect for spotting crabs. It's worth staying quite shallow on night dives and checking out the top of the bommies as a particular resident green turtle has grown too large to fit in the small overhangs at the bottom of the bommies and sleeps on top of them instead.

Moore Reef

Located 55 km offshore from Cairns, Moore Reef seems to act as a nursery for the surrounding nearby Great Barrier Reef area with juvenile fish finding shelter in an assortment of rock formations. These rock formations are covered with hard and soft corals with excellent shelter between staghorn thickets from predators and curious divers.
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The staghorn thickets are interspersed with gullies that lead up to the reef. They make for excellent spots from where you can observe the marine life within the coral. The sandy floor of the gullies have a few truly enormous giant clams. These clams, a leading highlight for divers in Cairns, can be up to 2 metres in length and 150 years old, and care should be taken around them as inadvertent fin kicks can cause sand to swirl into them. The giant clams make good photo opportunities, especially with a scuba diver beside them to show their sheer size.

The sandy channels of Moore Reef are the best place for spotting rays and occasional gray reef sharks, although you will be more likely to see white tip reef sharks on this dive. Schooling juvenile barracuda seem to be hurtling everywhere and you will see many pairs of butterfly and angelfish. If you like pelagic action, schools of trevally and mackerel dot the visible boundary of the blue just off the reef, waiting in the wings for an opportune moment to dart in and make a meal out of a smaller fish who had a fatal lapse in concentrating on survival.

If you move away from the reef, the bommies are excellent for cardinal fish, parrot fish and sweetlips. Some of the larger bommies have exciting swimthroughs where you can find lionfish, Maori wrasse and nudibranchs. The soft corals hide a plethora of damselfish darting out to feed. Small shrimps and crabs also occur in good number. Moore Reef is one site where you will definitely want to have your macro lens with you.

Pellowe Reef

Large pelagic action! Barracuda, jacks, sharks, dolphins and rays can often be found here. Interesting residents of the reef include Napoleon wrasse, octopus and moray eels. That's what you can expect from the small, isolated Cairns barrier reef that is Pellowe Reef, some 60 km offshore. It's abundance of big fish action is thanks to its proximity to the edge of the continental shelf.
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But the downside to its location is that it is somewhat exposed and sometimes affected by adverse weather conditions and currents, which make it inaccessible as times. Nevertheless, Pellowe Reef is popular amongst Cairns liveaboards plying the area due its busy marine life, a great wall dive and stunning swimthroughs.

Most of your diving on Pellow Reef will take place between 5-20m, although the reef does drop away to 30m in some places. A great way to start is by fixing a heading of 120 degrees after dropping down the mooring line; this will take you past an excellent swim through on your way to the main reef. Squirrelfish and sergeant majors seemingly cover the whole coralscape, along with resident humphead Maori wrasse or Napoleon wrasse. These can grow to over 2m in length and weight almost 200 kilos, making for an impressive and humbling encounter.

You will also catch sight of impressive bull rays up to 2m across. Keep a lookout for white tip sharks, which you can spot cruising over the bottom. You should explore the nooks and crannies of the reef too as you will spot moray eels, octopus and a variety of sea cucumbers and nudibranchs.

Cairns scuba diving offers both plentiful hard and soft corals and these are home to a diverse range of marine life, such as anemones and their playful resident clownfish, making it a great site for snorkelers as well, since there is plenty of action in the shallow waters. The area is popular also with dolphins. Arriving or departing dive boats often have a dolphin escort, effortlessly keeping up or playing in the bow wave.

Thetford Reef

This reef stretches for almost 2 kms. It consists of a series of scattered coral bommies bejeweled with vivid hard and soft corals and supports a diverse wealth of marine life, making it a wonderful dive site.
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If you peer down to the sandy floor at 25m, there are channels which run between the many bommies. Here you might see some of the giant clams that the area is so well known for. Some examples reach several metres in length! Stingrays also frequent these channels often half-burying themselves in the sand. You should also keep an eye out around the many overhangs and ledges of the bommies where you can spot and take some great photographs of turtles at rest.

In some places the coral bommies meet overhead, creating swimthroughs that are perfect backdrops for underwater photos. The swimthroughs have gorgonian fans in them that are home to tiny critters, easily spotted by the keen eye. Be sure to take extreme care in the passageways though, and don't brush against the gorgonians as they damage easily. The bommies are surrounded by marine life with wrasse, angelfish, triggerfish and parrotfish, all being present in large numbers. Keep an eye out for Napoleon wrasse frequenting the reef, one of the highlights for scuba divers in Cairns.

Anemones are plentiful and several species of anemone fish live amongst them. Patches of staghorn between the bommies harbour good numbers of butterfly fish, damsels and angelfish. Multi coloured Christmas tree worms are also found on many of the bommies, which can provide plenty of amusement if you haven't come across them before.

Thetford Reef lends itself to underwater photography, with the shallower depth and sandy bottom providing plenty of light. The only problem is that there's just too much marine life to choose from and you find that your memory card just isn't big enough. With a healthy population of morays in Cairns you will have no trouble spotting them and there's always a possibility of a chance encounter with an octopus moving across the coral landscape.

Some of the dive boats that visit Thetford Reef conduct fish feeding so if you find that a trevally, emperor, red bass or even a school of fusiliers or sergeant majors are following you, don't panic, they have simply mistaken you for a waiter.

How to Dive Cairns

Cairns liveaboards

Various liveaboard trip options of different durations are available for your local diving adventure, and these run all year round so it's easy to work your schedule around a departure date and time that suits you. For more information on the cruises, duration options, and all the other travel information you might need to enter Australia, visit our Cairns liveaboard section.

Cairns is also the starting point for exceptional liveaboard diving cruises that visit the top spots on the Great Barrier Reef. The finest dives, which can be truly world-class, are found around Osprey Reef and the Ribbon Reefs. These are all found to the north of here and, depending on your choice of itinerary, may involve boarding or disembarking at Cairns or a stunning low level flight over the reef to or from Lizard Island. If you want to dive the best sites of the area then check out Osprey Reef and the Ribbon Reefs and the Australian liveaboards that visit these areas.

If you choose to dive the entry level sites of the Cairns Barrier Reef, which are some distance from shore, this requires a substantial amount of travel time. Although day trips are possible, most of the day is spent on travelling to and from your hotel and the reef. Dive The World therefore recommends a short liveaboard tour to maximise your time at the Barrier Reef.

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The Diving Season

As with the rest of the Great Barrier Reef, any time is a good time for diving in Cairns. The tropical weather ensures that the water temperature is always between 22 - 29°C. Sea surface conditions are calm, except during the Australian winter months when they can become moderate. The Great Barrier Reef is blessed with perpetual great visibility and during September to November it goes from great to excellent.

Special times of the year on the Great Barrier Reef are from June - November when humpback whales are commonly spotted, and in October / November during coral spawning. This is in addition to the usual magical spectacle which characterises the reef all year round.

The summer season of Cairns sees a little more rain than the dry winter seasons, although rainfall is still moderate and showers generally occur in the early mornings and late afternoons.

Visit the Bureau of Meteorology website for more information on the climate and sea conditions that greet divers in Cairns.

Where is Cairns and How Do I Get There?

Review our maps below of Great Barrier Reef, showing the location of Cairns, and its host country Australia. Here, you will find information on how to get to Cairns.

Reef Summary

Depth: 5 - 30m
Visibility: 5 - 20m
Currents: Gentle
Surface conditions: Generally calm but can be choppy
Water temperature: 25 - 30°C
Experience level: Beginner - intermediate
Number of dive sites: 16
Distance: 60 km east of Cairns
Recommended length of stay: 3 - 5 days

Useful References

• Cairns tour options: Cruise trips - Daytrip diving
• Diving videos
• Great Barrier Reef Marine Park
• Tourist activities: Queensland  -  Cairns
• Maps: Map of Australia - Great Barrier Reef
• Frequently asked questions