Turtles and history
Low Isles
Off Port Douglas
- Crossing30 minutes
- On landLighthouse walk
- GroupUp to 23
Help me decide
Low Isles vs Green Island, with Mackay Cay as the wild card
Low Isles glass bottom boat and snorkel from Port Douglas
★ 4.7 · 521 written reviews
Answer in brief
Low Isles vs Green Island comes down to your base: Low Isles is the quiet lighthouse cay off Port Douglas, Green Island the busier rainforest cay off Cairns.
Cay essentials
Two questions, one cay
Which coral cay suits your stay
Say where you are staying and what your group needs, and a cay day appears with its starting price.
Recommended for you
Low Isles half day
from $173
The lighthouse cay off Port Douglas, 4 hours with a snorkel and a glass bottom boat.
Recommended for you
Green Island cruise
from $78
45 minutes from Cairns by fast catamaran, with a pool, showers and food on the island.
Recommended for you
Outer reef full day
from $237
A full day to the outer reef from Port Douglas for confident swimmers.
Low Isles vs Green Island is really Port Douglas against Cairns: two inner cays with very different days. Mackay Cay is the remote outer option. Here is the comparison in full.
Editorial team, lowislestour.com · Updated November 8, 2026 · A 7 min read
Main facts
- Low IslesFrom Port Douglas, 8.5 nautical miles out, with a lighthouse.1,2
- Green IslandFrom Cairns, 45 minutes by fast catamaran, rainforest and a resort.3
- Mackay CayFrom Port Douglas, 28 nautical miles out on the outer reef.1
- Cheapest dayThe Green Island cruises start from $77.
- Smallest groupOur Low Isles boat takes 23 guests at most.
Coral cays with very different days
Each of these is a coral cay on the Great Barrier Reef, and each can be reached in a day. That is where the likeness ends. Low Isles is a small inner cay off Port Douglas with a lighthouse and a mangrove neighbor; Green Island is a forested cay off Cairns with a resort and day facilities; Mackay Cay is a bare sand cay on the outer reef, reached by a long sail from Port Douglas.
The departure town decides more than people expect. Tourism Australia puts Port Douglas about an hour of driving up the coast from Cairns.4 If you are staying in Cairns, Green Island is the natural choice and Low Isles means a transfer north first. If you are staying in Port Douglas, the reverse applies, and Mackay Cay becomes a realistic big day out.
The Reef Authority treats these places differently too. Low Island Locality is a Sensitive Location with a low use setting, while the Green Island localities 1 and 2 are classed as moderate use locations.5,6 Mackay Cay appears on the Reef Authority list of bird nesting and roosting sites where visitors must take care not to disturb the birds.7 In plain words: Low Isles is managed for small numbers, Green Island for more, Mackay Cay for the birds.
Cay against cay
Low Isles, Green Island and Mackay Cay
| Point | Low Isles | Green Island | Mackay Cay |
|---|---|---|---|
| Leaves from | Port Douglas | Cairns | Port Douglas15 |
| Distance or time | 8.5 nautical miles1 | 45 minutes3 | 28 nautical miles1 |
| On land | Lighthouse & museum16 | Rainforest & resort17 | White sand cay18 |
| Facilities | Thatched shade16 | Showers & pool | Moored boat only18 |
| Use setting | Low use5 | Moderate use6 | Bird nesting site7 |
| From price | $173 | $77 | Sailing day only |
Sources: the Reef Authority, the operators and the listings in the table; prices shown are opening fares, not quotes.
Low Isles: the lighthouse cay off Port Douglas
Low Isles is a pair of islands. Tourism Port Douglas Daintree describes the uninhabited, mangrove-covered Woody Island and the smaller vegetated sand cay of Low Isle, ringed by 55 acres of inshore reef.10 Sailaway puts the island 8.5 nautical miles from Port Douglas.1 Its lighthouse was built in 1878 and kept by keepers until it was automated in 1993.2
A visit is about turtles, the lagoon and the island walk. The reef notes from Sailaway list 150 hard coral species around the cay and daily sightings of green turtles.11 On the trip this site books you get 1.5 hours there for the lagoon, the glass bottom boat and the sand, with a limit of 23 guests aboard.
There is no resort. Federal and Queensland park staff look after it together, and its neighbor Woody Island closes seasonally to protect nesting birds: the current closure runs until 1 March 2027.12,13 What you get is a quiet cay with a lighthouse and a lagoon, not a day resort, and for the right traveler that stillness is the whole appeal of the place.
Green Island: rainforest, a resort and day facilities
Green Island is the Cairns answer to Low Isles. Its day operator describes it as a national park of approximately 12 hectares with both reef and rainforest, and says that it alone, among 300 coral cays of the reef, carries a rainforest.17,20 It was named in 1770 after Charles Green, the astronomer on HMS Endeavour.8
It is much better equipped than Low Isles. The Green Island cruise listing names restrooms, freshwater showers, a swimming pool and food and drink outlets on the island. Green Island Resort says the island is 45 minutes from Cairns by fast catamaran.3 That makes it an easy day with children or with someone who needs a shower and a proper lunch.
The reef has been through a rough patch. The Reef Authority says the reef at Green Island shows the impact of crown-of-thorns starfish, cyclones and coral bleaching.21 Expect a busier beach than at Low Isles and a reef that is recovering, with good facilities to make up for it. A glass bottom boat or snorkel option comes with the main Green Island cruise listing, so non-swimmers are catered for there as well.
Pick your cay
Lighthouse, rainforest or open reef
Mackay Cay: the remote outer reef sand cay
Mackay Cay is the wild card. Sailaway puts it 28 nautical miles from Port Douglas, on the outer reef, and claims to be the sole Port Douglas operator going there every day.1,15 Its sailing day moors at the outer reef for 4.5 hours, so this is a full day by definition.19 GetYourGuide carries no listing for the cay itself, so this site does not book it; book it with the operator directly.
The reef is the reason to go. Sailaway writes of giant clams dotted across the shallow reef, the biggest reaching 1.5 meters and close to 80 years of age.24 It also warns that the snorkel site is shallow yet out of your depth, so swimming ability is a must.23 The operator describes its outer reef tour as best for intermediate swimmers.25
Sailaway describes the outer cays as pure white sand inside a large fringing reef, with the boat moored on the sheltered side.18 There is no lighthouse, no rainforest and no resort, and the birds have priority. The Reef Authority lists Mackay Cay among the sites where visitors must not disturb nesting and roosting birds.7 For strong swimmers who want an outer reef day with a beach, it is the most remote option on this page.
Compare the fares
Price Low Isles against Green Island
Enter your party size to compare an island day off each town.
Side-by-side: 3 options
Price Low Isles against Green Island
Enter your party size to compare an island day off each town.
- Low Isles half day4 hours · per visitor from $173
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View - Green Island cruise5 to 9 hours · per visitor from $78
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View - Green Island full day8 hours · per visitor from $77
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View
Starting prices as on the booking platform, converted at the ECB reference rate. You see the exact price at booking.
Histories in brief
How each cay got its story
Green Island
Named after an astronomer
Named in 1770 after Charles Green of HMS Endeavour.8
Low Isles
The lighthouse is lit
The lighthouse was built in 1878.2
Low Isles
Weather records begin
The island has kept weather records since 1887.9
Low Isles
A year of reef science
In 1928 the island was the base for a year-long reef survey.9
Low Isles
Keepers leave
The lighthouse was automated in 1993.2
Low Isles vs Mackay Cay from the same marina
Both trips can start at the Port Douglas marina, so Low Isles vs Mackay Cay is a pure question of distance and swimming. Low Isles is 8.5 nautical miles away and Mackay Cay 28.1 Our Low Isles trip takes 4 hours in total; the Mackay Cay sail is a full day with 4.5 hours at the reef.19 That gap is the whole decision: a morning with time left for the rainforest, or a day given entirely to the open reef.
Low Isles is gentler. Reef Sprinter steers beginners there for its shelter and shallow water.26 On our trip you can wade in off the sand or slip in from the stern.27 Mackay Cay asks you to swim in water where you cannot stand.23 If one person in your party is unsure in the water, the gentler island keeps the whole group together instead of leaving someone on the boat.
Low Isles has more to do on land: the light tower, the old keeper quarters and the weather station line the sandy paths.28 Mackay Cay has more reef. A family with young children or a non-swimmer should pick Low Isles; a pair of strong snorkelers with a whole day to spend can make the case for Mackay Cay.
Video
A Green Island day trip from Cairns
Aquarius Traveller on YouTube · Playback files load only once you tap play.
Of the 300 coral cays in the Great Barrier Reef, Green Island is the only one with a rainforest.
Pack for the cay
What to bring to each island
For Low Isles3
For Green Island3
- Check-in at the Reef Fleet Terminal, Cairns
- Swimwear for the pool and the beach
- Patience on a busy day
Crowds, facilities and how the day feels
Crowds are the biggest difference you will feel on the sand. Green Island is a busy day destination with a resort, a pool and food outlets, and its two listings on GetYourGuide alone carry 1,726 and 1,692 reviews. Low Isles is managed for low use, and our boat lands no more than 23 guests.5 On a quiet morning the beach can feel almost private, which is what many visitors come for.
Facilities follow the crowds. On Green Island you can shower, swim in a pool and buy lunch. On Low Isles you get shade under thatched umbrellas, the lighthouse and a small museum, as the tourism board describes it.16 Pack for a morning ashore and carry a card, since our boat accepts no cash. Water, a hat and a light shirt matter more here than at Green Island, where you can simply buy what you forgot.
Mackay Cay is the emptiest and the most exposed of these cays. It is a cay of white sand inside its reef, and the long crossing means the weather plays a bigger part.18,1 For people who love a quiet beach and do not need a café, that is the appeal; for others, it is the reason to choose Green Island. Bring water, sun protection and a light layer for the long sail home, when the breeze can feel cool after hours in the sea.
Low Isles vs Green Island: the verdict
Choose Low Isles if you are staying in Port Douglas, want a small group, care about turtles and history, and are happy without facilities. The half day on this site costs from $173 for 4 hours, and the full sailing day from $194 for 7. Either way you meet the lighthouse, the lagoon and, very likely, a turtle grazing in the shallows.
Choose Green Island if you are staying in Cairns, travel with children who need a pool and a toilet, or want the cheapest reef day. The Green Island cruises start from $77 and $78, and run from 5 to 9 hours. The trade-off is more people and a reef that has taken knocks.21 For a first reef day with small children, though, the pool, the showers and the short crossing make Green Island hard to beat.
Choose Mackay Cay if you are a strong swimmer staying in Port Douglas and want the outer reef with a sand cay attached. It is the longest and most remote trip on this page, and the one most dependent on the weather. Whichever you pick, book early enough in your stay to move the date if the wind is up.
FAQ
The short answers to your questions.
Is Low Isles better than Green Island?
Quieter, yes; easier, no.
Low Isles is managed for low use; Green Island has showers, a pool and food outlets.5
Which is closer, Green Island or Low Isles?
Each is close to its own town.
Green Island is 45 minutes from Cairns; our boat reaches Low Isles in 30 minutes from Port Douglas.3
Can you visit Mackay Cay from Port Douglas?
Yes, by sailing day.
Sailaway says it is the only Port Douglas operator with daily access to the cay.15
Does Green Island have a rainforest?
Yes.
Its operator says it is the only one of the reef's 300 coral cays with a rainforest.20
Which cay is best for non-swimmers?
Low Isles or Green Island.
Both offer glass bottom boats; at Mackay Cay you must swim where you cannot stand.23
Is there food on Low Isles?
Not on the island.
Food is served on board some trips; Green Island has food and drink outlets ashore.29
Why is Mackay Cay a sensitive site?
Nesting birds.
The Reef Authority lists it where visitors must not disturb nesting and roosting birds.7
Which cay trip is cheapest?
Green Island.
Green Island cruises start from $77; our Low Isles half day from $173.
Sources
- Sailaway Port Douglas (operator official site) · FAQs ↩
- Sailaway Port Douglas (operator official site) · Reef Destinations ↩
- Green Island Resort (official site) · Green Island Resort ↩
- Tourism Australia (australia.com) · Travel guide to Port Douglas ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Cairns / Cooktown site specific management ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Cairns / Cooktown site specific management ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Cairns Area Plan of Management ↩
- Great Adventures (operator official site) · About Green Island ↩
- Sailaway Port Douglas (operator official site) · Reef Destinations ↩
- Tourism Port Douglas Daintree (official regional tourism organisation) · Your 6 step guide to getting to Low Isles ↩
- Sailaway Port Douglas (operator official site) · Reef Destinations ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Seasonal closure: Woody Island, Low Isles ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Seasonal closure: Woody Island, Low Isles ↩
- Reef Sprinter (operator official site) · Low Isles reef and lagoon tour ↩
- Sailaway Port Douglas (operator official site) · Mackay Coral Cay Outer Reef Tour ↩
- Tourism Port Douglas Daintree (official regional tourism organisation) · Low Isles ↩
- Great Adventures (operator official site) · About Green Island ↩
- Sailaway Port Douglas (operator official site) · Reef Destinations ↩
- Sailaway Port Douglas (operator official site) · Mackay Coral Cay Outer Reef Tour ↩
- Great Adventures (operator official site) · About Green Island ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Green Island reef rehabilitation project ↩
- Great Barrier Reef Marine Park Authority (gbrmpa.gov.au) · Caution advised: Low Isles reopens ↩
- Sailaway Port Douglas (operator official site) · Reef Destinations ↩
- Sailaway Port Douglas (operator official site) · Reef Destinations ↩
- Sailaway Port Douglas (operator official site) · Mackay Coral Cay Outer Reef Tour ↩
- Reef Sprinter (operator official site) · FAQs ↩
- Tourism Port Douglas Daintree (official regional tourism organisation) · Calypso - Low Isles Half Day Snorkelling ↩
- Tourism Port Douglas Daintree (official regional tourism organisation) · Calypso - Low Isles Half Day Snorkelling ↩
- Sailaway Port Douglas (operator official site) · Full Day Low Isles Tour ↩
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