‘The Green Temple’: Greens Pool and its custodians
NICOLE HODGSON knows the strong allure of Greens Pool in William Bay National Park — she swims there regularly, just one of the 600,000 people who have flocked to Greens Pool over the past 12 months, drawn to the calm turquoise waters bounded by moody granite boulders. For most visitors, it is simply a stunning place to visit, explore and swim. But for a small, dedicated community of swimmers, snorkellers, and citizen scientists, Greens Pool is a sanctuary, a social hub, and a diverse marine ecosystem that needs protection.
Narrated by Nicole, this story features three locals — Bernard Wong, Tim Gamblin and Susan Hawson — who have spent many years observing the pool’s marine life, documenting it, and helping to build a broader ethic of custodianship and care.
May 2026
Bernard Wong has swum here for at least thirty years, and he was a key member of the Working Group that advocated successfully for marine conservation at Greens Pool. A fishing ban came into effect in December 2018, applying to all taking of marine life from a small area just around the pool. Working on that process was the catalyst for him to look more closely at his favourite swimming spot.
Bernard: As part of identifying why Greens Pool is so valuable to the public for swimming and snorkelling, I decided to start documenting what we have here. Once I started taking photos and identifying all the different species, it has all become more and more interesting from a citizen science point of view. I found that it’s quite diverse, and importantly it’s a little microcosm of the Great Southern Reef that we don’t have elsewhere. It’s probably one of the few spots along the southern WA section of the Great Southern Reef where you can jump in relatively safely and look at everything. It is really precious.
The Great Southern Reef describes the stretch of about 8,000 km of coastline from Kalbarri right around to northern New South Wales. It is not one continuous line of reef, but rather an enormous interconnected system of temperate rocky reefs, renowned for the high levels of biodiversity.
Tim Gamblin, who works as a terrestrial zoologist, began snorkelling regularly at Greens Pool 10 years ago. People often approached him with questions about the fish they had seen.
Tim: My plan was to get clear photos of the most common fish and produce a small booklet for identification. So that was the start — that’s why I bought the camera. And the problem is, and it’s why I haven’t produced the guide, there was no easy way to draw the line. Do I feature just the 10 most common species? But there are actually 20 or more common species. And what about the invertebrates? It just got bigger and bigger.
Susie is a more recent addition to the Greens Pool swimming and citizen science community. From late 2020 she began swimming for fitness after a bilateral knee replacement meant she could no longer run.
Susie: I fell in love with the magic of Greens Pool immediately. As I gained confidence, all I wanted was to see an octopus. I began to learn what to look for and I was hooked on occy spotting. I have always been an amateur photographer, so I decided that I would invest in an underwater camera. Now I get such great joy from looking for beautiful ocean creatures and then sharing the photos and videos with friends and on social media. It is only these past five years that I have truly come to love and appreciate the ocean and the amazing creatures that live within it.
Along with Bernard, Tim and Susie, there is an informal but committed network of observers of the marine life at Greens Pool. People share sightings regularly — on the beach, in the water, or through the iNaturalist app. Bernard hopes to formalise this into a dedicated Greens Pool project page to build a more complete dataset of the marine biodiversity.
Bernard: When people get a connection with a place, the custodial feeling gets greater, and the more connection they have the more they want to look after it, and that’s the next level of custodianship we want.
Tim: As we know in conservation, once you know just the name of a species, you start to feel a sense of ownership, and that helps with the protection of its habitat.
Susie: Greens Pool means so much to so many people. The regular swimmers are an amazing group and their passion and sense of care for the pool is wonderful. You often see the local swimmers, and Greg from the food van, gathering rubbish before they depart the carpark. The William Bay National Park Association do a fabulous job in revegetating the land-based part of the national park.
Tim: The love for Greens Pool is being passed onto the next generation too. When my daughter Pia first came here, she couldn’t swim. She would hang off my shoulders and be quite nervous. Eventually she could swim, and now she’s diving. She’s got a GoPro and stays out in the water longer than me, and she’s out doing her own thing half the time. There’s no pressure from me.
Greens Pool offers a rare combination of mostly safe swimming conditions and rich marine biodiversity. This accessibility is part of what makes the place special. But it is also what makes it vulnerable to pressures from over-tourism. Visitation has surged in recent years, and in peak periods, cars line the road for a kilometre or more. In the water, fish behaviour can shift with an increased volume of humans, or the sunscreen slick on the water can be detectable. The ocean is warming, and marine heatwaves have swept the south coast in recent years, bringing in tropical species far beyond their usual range. Creating marine reserves and no-take zones is one way to build resilience in marine ecosystems.
It has been seven years since the fishing ban at Greens Pool was enacted, and the consensus is that the marine life has flourished ever since, even if that is based on mostly anecdotal data.
Tim: As soon as you swim outside the no-take zone, which is a really tiny area, you can see the difference in the ecosystem straight away. It’s much more biodiverse in here, even compared to just five hundred metres away. You can see how much this no-take zone is actually working.
Susie: The fact that Greens Pool is a marine reserve should never be changed. Some illegal fishing does still take place. In December 2024, I came across the remains of two or three wobbegong sharks that had been killed in Greens Pool. I would like to see the no-take zone expanded and more resourcing for the park rangers, who have to cover the whole national park.
Bernard: I think the real problem in surrounding areas is spear fishing and the targeting of trophy species, like the slow-growing blue groper. I would really like to see a ban on spear-fishing from the boundary of the William Bay National Park out to three nautical miles. There should also be a ban on all fishing of blue groper in this zone, similar to what was enacted around Rottnest Island.
The more the citizen scientists at Greens Pool looked, the more questions arose about fish physiology and behaviour, and about ecosystem interactions.
Bernard: As we started documenting and classifying, I got more and more interested in what the ecosystem is doing. Looking at the role of abalone is one example. When they had all been taken out and that filtering function was removed from the area, it had an impact on the system. Now, they are back in Greens Pool, with the no-take zone in place, and a whole host of other species have come back as a result. Other fish have come in to feed on those species, so there’s more ecosystem health here and a better habitat for fish breeding.
Tim: There’s plenty of research to show that no-take-zones, or marine parks, are not static protection areas — they are ‘engine rooms’ that produce a lot of marine life, boosting fisheries stocks outside their boundaries. There’s also some evidence that fish populations in protection areas are more resilient to climate change, possibly due to increasing individual’s reproductive output.
At one point Bernard thought he had “run out of fish” to document, so he started identifying the invertebrates and everything else in the pool. But even after years of near daily swims, he saw a species he had never seen at Greens Pool before – a Western grunter. Tim is also always on the lookout for species he hasn’t seen within the pool.
Tim: What is exciting is that not only can you still find species not seen before at Greens Pool, but there is still so much that is unknown. I often send observations to a friend who heads the fish department at the WA Museum. I’ll say, “We’ve seen this pipefish, or we’ve seen this fish changing colours. We don’t know what that behaviour means. Do you have any idea?” And generally, the answer is, “We don’t know. That’s interesting. Keep looking.” So the experts don’t necessarily know. Which means that anyone can come down here and discover something new just by observing. It’s open to all citizen scientists.
Susie: I have been so very lucky on several occasions to have captured some remarkable footage of an octopus’s courting and mating performance. The male octopus was changing colour and doing a courtship dance for the female before transferring his sperm into her using his third arm. I also loved finding two wandering sea anemones — during the day they look like a ball of baked beans.
The continual observation also allows these citizen scientists to take note of the constant changes.
Tim: There are the daily changes and the seasonal changes. In winter you’ll see pomfrets, then in summer they’ve moved out. In the late afternoon, you’ll start to see the blue devils and bullseyes coming out from the caves because they’re feeling braver. The sun’s going down so there’s different food, different behaviour. There’s a whole other level of snorkelling just in changing the time of day.
There is a vital social and cultural component to Greens Pool too. For many regulars, it is a place of ritual, solace, and transformation.
Tim: Greens Pool is like a ‘wet café’ where everyone comes down at different times, but chances are you’ll see someone you know. Everyone’s doing different things. Some are swimming for fitness, some to socialise and relax and others are doing the serious citizen science photography. But everyone is sharing. There are not many other places where you can be swimming along and a complete stranger will swim up to you and say, “There’s an ocky at that rock down there” or point out where they saw a blue devil.
Bernard: It is a kind of religious experience. We call it the Green Temple for a good reason, because we bathe in it and bask in it.
Susie: Greens Pool is my happy place and my morning swims there have been a great solace to me in difficult times. Just walking down the steps towards the ocean and that first glimpse of the water, be it calm or rough, is such a joy. Each day is different and each day is just as amazing.
Tim: Greens Pool has changed me. I used to come down here and only take underwater photographs. If I left my camera at home, I’d feel so disappointed that I almost wouldn’t want to swim. Now, at least half the time I leave the camera at home and don’t even bother with a mask — I just want to get in and swim and enjoy it for what it is, to be a part of the ocean.
THANKS TO Nicole Hodgson, Bernard Wong, Tim Gamblin, Susan Hawson, William Bay National Park Association. Editorial input from Marg Robertson. Gondwana Link respectfully acknowledges the Pibulmun and Menang Peoples as the Traditional Custodians of the Country where this story is based.
FURTHER INFORMATION
DBCA pamphlet about visiting Greens Pool
William Bay National Parks Association
The story of the campaign to ban fishing at Greens Pool by Denmark Environment Centre
