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Norfolk Island's Reef

Discover a fragile paradise – Norfolk Island's beaches, lagoons and coral reef
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  • Out on a swim - blog
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Out on A Swim

‘Out on a swim’ is a coral reef blog that tells the stories of the characters who live under the waves and what has caught my eye when ‘out on a swim’ in the lagoons of Norfolk Island. It is also a record of the difficulties Norfolk Island’s reef faces, like many others around the world, as a result of the poor water quality that has been allowed to flow onto it.

This page shows the most recent blog posts. For the complete catalogue, visit the ‘Out on a swim index’ page.

This blog is rated in the Top 20 Coral Reef Blogs in the world.

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Eclipse butterflyfish – Chaetodon bennetti, Norfolk Island

Celebrating Biodiversity Month on Norfolk Island

September 7, 2025

September is Biodiversity Month – the perfect time to celebrate the astonishing variety of life on Norfolk Island’s reef. From new fish sightings to coral mosaics, every observation is a reminder of how much there is still to learn and protect.

Read more about why biodiversity matters, globally and right here in our lagoon.

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In Biodiversity Tags biodiversity, Fish, corals, Norfolk Island, Emily Bay, Slaughter Bay
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Cute as buttons – Astrea curta

February 20, 2025

Astrea curta corals are ‘small, moderately plocoid [flattened], distinct, and almost circular’ . Normally grey-green in colour, you can see from the images here, ours are often beautiful rich gold, although they do vary. They have a neat growth habit and button-like corallites, which can grow in columns, spherically or flattened. Large colonies of these can form gorgeous undulating bumps.

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In Corals Tags corals, Astrea curta, Norfolk Island, Emily Bay, Slaughter Bay
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The Emily Bay’s massive ‘brain’ coral, Paragoniastrea australensis, photographed on 6 July 2024

While you were sleeping ...

July 10, 2024

This massive and incredibly slow-growing Paragoniastrea australensis sits in Emily Bay on Norfolk Island and is one of our most recognisable bommies. While all looks reasonably calm during the day, at night, while you are sleeping, the surface of the coral colony seethes with millions of tiny tentacles busily reaching out to find food, while others aggressively ward off opportunistic interlopers.

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In Corals Tags corals, coral reef, bommie, Emily Bay, Norfolk Island
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Green moon wrasse, Emily Bay, Norfolk Island

I only have fish eyes for you!

February 22, 2024

Do fish have eyes that move independently? Well, no, not really, but, yes, sort of, in some species, sometimes!

Read on for a brief ‘Fish eyes 101’ summary of how they work.

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In Fish Tags fisheye, Fish, fish species, anatomy, Norfolk Island, Emily Bay
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Emily Bay, full moon rising, by Norfolk Island photographer Joelene Oliver

Full moon, low tides and Norfolk Island’s reef

June 2, 2023

With the low, low tides associated with a full moon, the bays on Norfolk Island are like a huge, calm swimming pool, giving us some great snorkelling opportunities. These low tides should also let us view the causeway, which will no doubt be exposed too. This post explores these opportunities as well as what the low tides mean for corals. Read more in this fact packed blog post.

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In Corals Tags Norfolk Island, Full moon, Low tide, HMS Sirius, causeway, Emily Bay, Slaughter Bay, coral reef, corals, plastic, plastic pollution
2 Comments

My grandson

For the sake of our grandchildren

March 26, 2023

What will my grandson see when he is old enough to snorkel on Norfolk Island’s reef? Will there be anything left as I know it? Or will he think it is all great because of that hoary old phenomenon called ‘shifting baseline syndrome’? This record of all my photos and observations will give him some idea of what we had in our bays in the 2020s.

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In Environmental degradation, Fish species Tags Environment, Environmental protection, water quality, biodiversity, grandchildren, Norfolk Island, Emily Bay
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Emily Bay, Norfolk Island, #thecoloursarereal!

Beneath the waves in Emily Bay, Norfolk Island

March 20, 2023

Looking across Emily Bay, do you wonder what is beneath the waves in there? Although this is not strictly part of Norfolk Island’s reef, it is part of one continuous ecosystem; therefore, in today’s March focus on Norfolk Island’s reef I thought it was worth showing you what you can see at your feet as you wade into the shallows.

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In Ecosystem Tags Emily Bay, Snorkelling, Fish, fish species, ecosystem
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Norfolk Island's Blenny Fest

October 31, 2022

At this time of year, as the mating season begins, the delightful little Lady Musgrave blennies, Cirripectes chelomatus, change colour from dark inky blue black with a few barely visible red spots to a showy and vibrant mustard yellow.

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Tags Norfolk Island, Emily Bay, Fish behaviour, Blenny, Lady Musgrave blenny, coral reef
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A flatworm, Pseudobiceros sp, dining on the tunicates

Sea squirts – friend or foe?

October 17, 2022

Emily Bay and Slaughter Bay have recently experienced a significant increase in the numbers of overgrowing tunicates. In this post I take a look at these critters – which, incredibly, are distant cousins to humans – and ask some questions about their presence and impact on our coral reef ecosystem.

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In Ecosystem Tags tunicates, sea squirts, coral reef, corals, SlaughterBay, Emily Bay, ecosystem, biofouling, flatworms, ocean, Norfolk Island
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Surge wrasse – Thalassoma purpureum

No, it's not a parrotfish!

June 26, 2022

Wrasse and parrotfish often get confused, but they each have quite differen roles to play on our reefs. Parrotfish are vital to the health of coral reefs. They clean up the surface algae that live on and compete with the coral. Read more to find out how they differ.

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Tags parrotfish, wrasse, Emily Bay, SlaughterBay, Cemetery Bay, Norfolk Island
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Tonna melanostoma

Citizen science in action on Norfolk Island

February 28, 2022

My photos of the Tonna melanostoma, a giant underwater mollusc, are the only ones of the live animal in the public domain. We are so fortunate to have these special and rare creatures living in our coral-reef lagoons; their existence here serves to highlight what a special habitat Norfolk Island’s reef really is. It is an ecosystem that must be preserved at all costs.

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Tags Tonna melanostoma, Royal Belgian Society for Conchology, molluscs, tun shell, Emily Bay, Gloria Maris, ecosystem, rare sea snail
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Old Gnarly the swal doodle, Emily Bay, Norfolk Island

Old Gnarly, the swal doodle

January 1, 2022

When I’m out on my swim, one guy I always stop by and say hello to is Old Gnarly, a spotted porcupinefish known here as a swal doodle. He knows when I arrive. The first thing you see are his big luminescent white lips as he floats to the door of his cave. We pause, study each other for a moment, then I give him the thumbs up before continuing my swim. It is a precious moment when you connect with a wild animal like this, and it makes my day.

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Tags porcupinefish, puffer fish, Emily Bay, swal doodle
1 Comment

Stylocheilus striatus – commonly called the lined sea hare, blue ring sea hare or furry sea hare

Furry sea hares as eco-warriors

December 12, 2021

Stylocheilus striatus – commonly called the lined sea hare, blue ring sea hare or furry sea hare – have appeared in numbers at one end of the shallows of Emily Bay. These little sea hares are great to have around as they consume the toxic blue-green alga that fish and other herbivores don’t or can’t eat or tolerate.

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Tags sea hares, eco-warriors, ecosystem, algae, nutrients, pollution, water quality, Emily Bay
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#LittleFig, my puppa, following me in for a swim at Cemetery Bay, the island’s dog beach.

Penis fencing flatworms

November 2, 2021

Here’s a quick round up of what has been happening on Norfolk Island’s reef in the last couple of weeks. There is always so much going on. Read on to find out about the mating habits of flatworms, and see a busy bluestreak cleaner wrasse hard at work cleaning his wide variety of customers.

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Tags flatworms, Coral disease, Emily Bay, pollution, cleaner wrasse

Surge wrasse - Thalassoma purpureum

Nuptial colouration in blennies

October 12, 2021

Warmer water and some behavioural changes: some fish are getting their nuptial colours on, while others have started incubating eggs in their mouth. It is all happening ‘out on a swim’. Catch up on the last week in Norfolk Island’s lagoons here.

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Tags nuptual colouration, Blenny, Emily Bay, Raft, pontoon, Southern Eagle Ray, environment, ecosystem, water quality
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A school of sand mullet, Myxus elongatus

Report released into the health of Norfolk Island's reef

September 7, 2021

This week’s observations while out on a swim, included some very active and inquisitive green moon wrasse. One, in particular, followed me for a good half an hour as I made my way around the reef off the Salt House. Find out more about what was happening beneath the waves on Norfolk Island this week.

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Tags sea hares, green moon wrasse, sand mullet, school of fish, Emily Bay, water quality, pollution, Sydney Institute of Marine Science
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Convict snake eel - Leiuranus versicolor

Banded, convict and spotted snake eels - know the difference

August 31, 2021

A beautiful banded snake eel, Leiuranus semicinctus, popped into view on Saturday. These gorgeous guys are docile and will dive head first into the sand if you get too close. Read on to discover how many types of snake eel we have in Norfolk Island’s lagoons.

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Tags Snake eel, banded snake eel, Convict snake eel, Spotted snake eel, Norfolk cardinalfish, Emily Bay, cleaner wrasse
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Slaughter Bay from Point Hunter, Lone Pine, low tide 27 June 2021

Mid-winter fabulousness

June 29, 2021

There’s been plenty going on under the waves here on Norfolk island, while above the waves we’ve just had the most fabulous mid-winter weather. With a full moon on 24 June, we experienced some wonderful low, low tides. Did you know that peak low tides always lag the full moon (and new moon) by a day or so?

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Tags goatfish, snubnosed dart, Emily Bay, Norfolk Island, weather, nudibranch, sea hares
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Halfmoon grouper - Epinephelus rivulatus

Halfmoon grouper - Epinephelus rivulatus

Close encounter with a halfmoon grouper

December 18, 2020

A close encounter with a halfmoon grouper causes an amazing transformation from mottled red to mustard yellow.

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Tags Halfmoon grouper, Emily Bay, Norfolk Island, Epinephelus rivulatus, coral reef
Juvenile Norfolk cardinalfish, Ostorhinchus norfolcensis, under the raft, Emily Bay

Juvenile Norfolk cardinalfish, Ostorhinchus norfolcensis, under the raft, Emily Bay

Mouth-brooding Norfolk cardinalfish

December 4, 2020

Norfolk cardinalfish are called big eyes on Norfolk Island, and it is easy to see why! These guys are mouth brooders, as in the male nurtures the eggs in his mouth.

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Tags Norfolk cardinalfish, Mouth-brooder, Norfolk Island, Ostorhinchus norfolcensisas, Emily Bay
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Norfolk’s water quality – when action is reported as outcome
June 15, 2026
Norfolk’s water quality – when action is reported as outcome
June 15, 2026

A recent Australian Government media release presents investment, monitoring and catchment works as progress on Norfolk Island’s water quality. Some of that work is useful, and some of it was badly needed. But activity is not the same as proven improvement. This post looks at Kingston sewerage, wetlands, cattle, acid sulfate soils, groundwater and reef health, and asks whether Emily Bay and Slaughter Bay are actually being better protected.

June 15, 2026
How surgeonfishes got their name
June 14, 2026
How surgeonfishes got their name
June 14, 2026

Surgeonfish are named for the sharp little scalpels near their tails, but on Norfolk’s reef their more useful work happens at the other end. Pencil surgeonfish, bluespine unicornfish and their relatives help browse algae across the reef – a small daily job that becomes very valuable on an algae-rich lagoon reef like ours.

June 14, 2026
A shrimp storm
May 28, 2026
A shrimp storm
May 28, 2026

While setting my research cams last week, I swam into what looked like an underwater snowstorm. It appeared to be the aftermath of a mass moulting event, with large numbers of tiny, translucent shrimp-like exoskeletons drifting together near the surface.

May 28, 2026
Kingston dredging: what happens when a reef does not fit the framework
May 28, 2026
Kingston dredging: what happens when a reef does not fit the framework
May 28, 2026

This correspondence with DCCEEW is about more than one dredging proposal. It is about what happens when an ecologically distinctive place is assessed through standard tools that do not always make its most important values easy to see. I am publishing it here because that is something we need to be aware of, both on Norfolk Island and more broadly in Australia.

May 28, 2026
Kingston dredging: the project advances, the questions remain
May 24, 2026
Kingston dredging: the project advances, the questions remain
May 24, 2026

Kingston dredging is edging closer, and the paper trail is growing. This post brings together earlier correspondence with the Department and the latest media release so readers can see what has been asked, what has been answered, and what still remains unclear about the project, its rationale, and the protections proposed for the reef.

May 24, 2026
The lime-green coral in Slaughter Bay – a 40-year paper trail
May 17, 2026
The lime-green coral in Slaughter Bay – a 40-year paper trail
May 17, 2026

Green Mountain – the name I give this coral in my database – is a coral I’ve photographed for years as I swim past. Then I found its backstory in the Norfolk Island National Parks archives: a rough map, reused paper, a note in the margin – ‘still thriving’. That’s how baselines begin.

May 17, 2026
What Norfolk Island’s reef tells us about environmental blind spots
April 5, 2026
What Norfolk Island’s reef tells us about environmental blind spots
April 5, 2026

The Kingston dredging proposal on Norfolk Island raises a bigger question than dredging alone: how well do standard environmental assessment tools capture the real significance of a remote and unusual reef system like Norfolk Island’s?

April 5, 2026
Hammer coral time!
March 30, 2026
Hammer coral time!
March 30, 2026

Hammer corals have unique tentacles that are large, fleshy, and tubular; these terminate in a ‘T’-shaped, hammer-head or anchor. Beneath all these softly waving tentacles is an extraordinary skeleton structure, which helps define them as a large polyp stony coral.

March 30, 2026
Norfolk Island’s fishes: drifters, residents and the ones still missing
March 24, 2026
Norfolk Island’s fishes: drifters, residents and the ones still missing
March 24, 2026

Norfolk Island’s fish fauna reflects both connection and isolation. Some species may arrive from elsewhere as drifting larvae, some populations appear to persist locally, and some fishes known from islands on either side of Norfolk have still not been recorded here. This post looks at what old survey work, regional checklists and genetic studies suggest about that more complicated picture.

March 24, 2026
18 Jun 2025 (20)_crop.jpg
March 7, 2026
Alveopora or flowerpot coral – how to tell the difference
March 7, 2026

They look alike at first glance, but Alveopora and flowerpot corals are not the same. The easiest way to tell them apart is to count the tentacles.

March 7, 2026

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