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.
Read MoreA juvenile flowerpot coral (Goniopora)
‘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.
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A juvenile flowerpot coral (Goniopora)
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.
Read MoreA bubble-tip anemone claims its real estate
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.
Read MoreQuality Row, Kingston, Norfolk Island, January 2025. The year began deep in drought.
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.
Read MoreI 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.
Read MoreAerial image of Kingston Pier and the west end of Slaughter Bay, Norfolk Island. This map includes data from Airbus Imagery from the dates:20/06/2023–12/09/2023.
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.
Read MoreA view to the west of the historic Kingston Pier, which directly adjoins the coral reef lagoon system of Emily and Slaughter Bays. The dredge site is on its east and southern sides.
How much risk are we really taking with the planned dredging at Kingston Pier – and how much protection do our corals actually have on paper? This piece walks through what the federal approval does and doesn’t guarantee, explains why sediment and light matter so much to the reef, and asks the hard questions we need answered before we trade a deeper channel for a shallower future.
Read MoreEclipse butterflyfish – Chaetodon bennetti, Norfolk Island
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.
Read MoreDay 6 of this photo series from Norfolk Island coincides with the final day of the UN Ocean Conference in Nice. After a week of documenting decline, today’s post offers a different view – what reef recovery can look like when conditions improve. Drought in 2024 gave the reef a break, and the results were unmistakable: healthier corals, lower disease, and more fish. This is what’s possible if we act.
Read MoreI wrote about this massive coral in a blog post ‘The Ancient Massives’, 20 March 2022
Day 5 of my blog series for the UN Ocean Conference: two long-lived coral colonies in Norfolk’s lagoon died quietly from disease. No drama – just slow collapse and overgrowth by algae. A reminder that not all reef losses are loud, but they are happening.
Read MoreHynophora pilosa colony, Norfolk Island
Day 4 of a week-long photo series from Norfolk Island, shared during the UN Ocean Conference in Nice. Today’s post spotlights a Hydnophora pilosa colony where white syndrome appeared suddenly and spread quickly, taking out around a quarter of the coral. In the months that followed, algae quietly filled the gap – a subtle but telling shift from coral to algae that’s happening across the reef.
Read MoreAstrea 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.
Read MoreSlaughter Bay, Norfolk Island, March 2020
Last week, the chance of coral bleaching in Norfolk Island’s inshore lagoons was raised from ‘Watch’ to ‘Warning’ and will more than likely rise to Alert levels one and two in coming weeks. So why do I worry about water quality all the time when bleaching seems inevitable these days and so the reef is probably doomed anyway? Read on to find out.
Read MoreEmily Bay at low tide, early morning, December 2024
It is five years since I began wielding a camera underwater in Norfolk Island’s lagoons and my third ‘year in review’ for this ‘Out on a swim’ blog. And what a journey it has been. At least this year I have some great news to report, but – a bit like a curate’s egg (partly bad and partly good) – there are also some downers. Find out what 2024 has meant for Norfolk Island’s reef.
Read MoreIf corals had characters, then the Paragoniastrea spp. would be described as feisty, or even downright aggressive when it comes to asserting itself over its neighbours. They are also rather colourful.
Read MoreThis Acropora colony on Norfolk Island’s reef was photographed in 2021. Today it is no longer there. Weakened by disease, it was destroyed by a storm surge two years later, in December 2023
If disease were spreading through our native forests, if our trees were developing strange growths that hollowed them out, making them brittle in the face of each passing storm, would five years have slid by with the problem worsening by the day? That is exactly what is happening on Norfolk Island’s reef. Slowly, insidiously, it is dying and turning to slime.
Read MoreMontipora corals, Norfolk Island
Gorgeous, boring brown, Montipora corals! These beautiful coral colonies (and remember, these consist of loads of tiny little animals, which work together to create these amazing shapes) are one of our key reef-building corals. There are around 85 known species belonging to the Montipora genus.
Read MoreExtensive area of acropora coral affected by white syndrome on Norfolk Island’s reef
CSIRO are on Norfolk Island this week to present the findings of their report into water quality. As our Administrator, George Plant, says: ‘What the data shows us is that the quality of ground and surface water entering Emily and Slaughter Bays often contains high levels of contamination ... The health of the Emily and Slaughter Bay reef will continue to decline if we do not improve water quality.’
Read MoreOne of the first corals to catch my eye when I set out with my new camera in January 2020 was this stunning boulder coral that sits off the Salt House in Emily Bay. Regular swimmers would all be aware of its presence, but not many would realise that it is quite possibly an as-yet undescribed species of coral, which for the moment is known as Lobophyllia recta sensu Veron.
Read MoreThe Emily Bay’s massive ‘brain’ coral, Paragoniastrea australensis, photographed on 6 July 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.
Read MoreIs this Atramentous Necrosis? This January, examples of this disease are popping up across Emily Bay on Norfolk Island
This month, I have increasingly noticed a disease that is presenting differently to the white syndrome that we have sadly become used to seeing. With this disease the coral goes grey-ish black and sometimes looks like it is almost dissolving or melting away. The result is a tragedy for the coral. I talk to coral health researcher Associate Professor Tracy Ainsworth about what is going on.
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