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Norfolk Island's Reef

Discover a fragile paradise – Norfolk Island's beaches, lagoons and coral reef
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    • Kingston, Norfolk Island
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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.

Convict snake eel - Leiuranus versicolor

Banded, convict and spotted snake eels - know the difference

August 31, 2021

The last day of winter, but here on the island spring is already with us. The bees are furiously busy with the clover in our paddock and the lavender hedge, while the tips of the frangipani trees are pushing out new leaves.

Glorious sunshine and winds from the southwest for a couple of days this week meant I was battling against it while swimming at the weekend!

A beautiful banded snake eel, Leiuranus semicinctus, popped into view on Saturday (top image). I haven’t seen any of these, apart from one dead one a few weeks ago, over winter, so it was wonderful to see this handsome fellow the other day.

Banded snake eel - Leiuranus semicinctus

I often get asked if these are sea snakes and if they are dangerous. They are in fact, as their name suggests, eels, and I find them to be very docile and will generally swim away or dive incredibly fast into the sand when approached too closely.

We have a few different snake eels: spotted, banded and convict. I’ve included photos of all three here so you can see the difference. It has been suggested to me that we may have a couple of different subspecies of these – which are, as yet, undescribed – because a couple look a little different. This isn’t something I know much about, but it would be exciting beyond belief if we did have some unique ones here.

Below are images of the three different types of snake eels found in Norfolk Island’s lagoons.

View fullsize Ocellate snake eel - Myrichthys maculosus
Ocellate snake eel - Myrichthys maculosus
View fullsize Ocellate snake eel - Myrichthys maculosus
Ocellate snake eel - Myrichthys maculosus
View fullsize Ocellate snake eel - Myrichthys maculosus
Ocellate snake eel - Myrichthys maculosus
View fullsize Banded snake eel - Leiuranus semicinctus
Banded snake eel - Leiuranus semicinctus
View fullsize Banded snake eel - Leiuranus semicinctus
Banded snake eel - Leiuranus semicinctus
View fullsize Banded snake eel - Leiuranus semicinctus
Banded snake eel - Leiuranus semicinctus
View fullsize Convict snake eel - Leiuranus versicolor
Convict snake eel - Leiuranus versicolor
View fullsize Convict snake eel - Leiuranus versicolor
Convict snake eel - Leiuranus versicolor
View fullsize Convict snake eel - Leiuranus versicolor
Convict snake eel - Leiuranus versicolor
View fullsize Convict snake eel - Leiuranus versicolor
Convict snake eel - Leiuranus versicolor
View fullsize Convict snake eel - Leiuranus versicolor
Convict snake eel - Leiuranus versicolor
View fullsize Convict snake eel - Leiuranus versicolor
Convict snake eel - Leiuranus versicolor

A convict snake eel, Norfolk Island

One thing I love to watch is the bluestreak cleaner wrasse, Labroides dimidiatus, hard at work. You often see fish queueing up for a once-over from this little guy. This morning it looked like they were all getting in early for a spring clean! I’ve included a few photos of this busy beaver cleaning some yellowstripe goatfish, Mulloidichthys flavolineatus (left) and a Coral Sea gregory, Stegastes gascoynei (right).

View fullsize Bluestreak cleaner wrasse with goatfish
Bluestreak cleaner wrasse with goatfish
View fullsize Bluestreak cleaner wrasse with a Coral Sea gregory
Bluestreak cleaner wrasse with a Coral Sea gregory
Tags Snake eel, banded snake eel, Convict snake eel, Spotted snake eel, Norfolk cardinalfish, Emily Bay, cleaner wrasse
← Report released into the health of Norfolk Island's reefWhen corals go blue! →
Featured
Norfolk Island’s fishes: drifters, residents and the ones still missing
Mar 24, 2026
Norfolk Island’s fishes: drifters, residents and the ones still missing
Mar 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.

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

Mar 7, 2026
Norfolk’s lagoonal reef – the 2025 report, in plain English
Feb 27, 2026
Norfolk’s lagoonal reef – the 2025 report, in plain English
Feb 27, 2026

We now have the 2025 Norfolk Island reef health report, so I’m taking the opportunity to translate it into plain English here. Sadly, it’s more of the same story in Emily and Slaughter Bays – a reef that can cope with some stress, but is being asked to cope with too much, too often.

Feb 27, 2026
Halimeda’s night shift – why this reef algae changes colour
Feb 20, 2026
Halimeda’s night shift – why this reef algae changes colour
Feb 20, 2026

Halimeda is a calcareous green reef alga that forms new segments overnight, shifts from white to bright green by dawn, then pales again as calcification begins. A quick look at one of the reef’s smartest algae.

Feb 20, 2026
Reef real estate – a bubble-tip’s six-year stand-off
Jan 11, 2026
Reef real estate – a bubble-tip’s six-year stand-off
Jan 11, 2026

Reef space is finite, and nothing ‘shares’ it politely. This short photo essay follows one bubble-tip anemone on Norfolk Island’s lagoonal reef as it holds a crater surrounded by Montipora. The coral builds a rim; the anemone holds the centre. Six years apart, and the argument continues.

Jan 11, 2026
A year in review – 2025 on Norfolk Island's reef
Dec 28, 2025
A year in review – 2025 on Norfolk Island's reef
Dec 28, 2025

Norfolk Island’s reef in 2025 – a year in review. From NOAA bleaching alerts and the UN Ocean Conference ‘Warning Signs’ series to post-drought coral recovery and a wet winter revealed in long-term rainfall records, this post captures the wins, losses, and shifting baselines beneath the lagoon. Includes reef photos, highlights from Reef Relief, and standout stories from 2025 – from coral health and disease to boxfish biomimicry, sea urchins, nudibranchs, and heat-stress signals in anemones.

Dec 28, 2025
Herbicides, heritage, and an inshore reef: what happens when land management meets lagoon health
Dec 15, 2025
Herbicides, heritage, and an inshore reef: what happens when land management meets lagoon health
Dec 15, 2025

Herbicide use near Emily, Slaughter and Cemetery Bays raises questions about inshore reef health, heritage land management, and environmental protection on Norfolk Island.

Dec 15, 2025
Signs of bleaching – 8 December 2025
Dec 8, 2025
Signs of bleaching – 8 December 2025
Dec 8, 2025

I took these photographs this morning, Monday, 8 December 2025. A few warm days of settled weather, little cloud cover and low tides in the hottest part of the day have led to some early bleaching on our reef. Bleaching doesn’t always mean death for our corals, but it is concerning to have this so early in the summer season. Fingers crossed the conditions don’t last and the reef can recover.

Dec 8, 2025
Nature is my teacher
Dec 3, 2025
Nature is my teacher
Dec 3, 2025

This is a thank-you note. Five years after my first Out on a swim post – written with zero marine science quals and a head full of questions – I’m still in the water, now as a PhD candidate, because an extraordinary mix of locals, volunteers, researchers and public servants decided to share what they knew. This is the story of how nature – and a very patient community – became my teachers.

Dec 3, 2025
Reef grief: what dredging has done to other reefs
Nov 30, 2025
Reef grief: what dredging has done to other reefs
Nov 30, 2025

From Miami to Fiji, from Dubai to tiny village harbours on atolls, dredging near coral reefs has left a long trail of scars – even on ‘small’ projects. This follow-up to last week’s Kingston post walks through real examples of what happened elsewhere, and what that should make us think about before we dig up our own reef.

Nov 30, 2025

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