Published in Diver Magazine UK September 2020

by Nigel Marsh

From only a few feet away it looked like a sponge - just like all the other orange sponges I had seen on this rocky reef. But there was something different about this one that caught my eye.

I moved in closer for a better look and after studying it for several seconds thought ‘no, it’s just a sponge’. I was about to swim off, but something compelled me to have another look. I scrutinised the sponge and thought I could make out an eye, but I still wasn’t sure as the nearby sponges also had eye-like spots.

I then noticed something out-of-place, a very fine head lure with a tiny ball of bait at the end. This was no sponge, it was a frogfish, and a very rare species, the Glauert's frogfish (Allenichthys glauerti), a unique species only found in this area. I was diving the temperate waters of southwest Australia, and this strange frogfish was not the only unique species I encountered in this wonderful part of the world.

Western Australia is a vast destination to explore. The state covers an area of 2.5 million square kilometres and has a coastline of over 20,000km, spanning from the tropics to its cooler temperate waters. Many wonderful dive destinations are located off Western Australia, including the famous Ningaloo Reef, Rowley Shoals and Christmas Island. And while these tropical destinations offer fabulous diving, the states temperate waters are far more fascinating as the area is home to many unique and endemic species.

It was the prospect of these unique species that recently lured me and a good mate Stuart Ireland to spend a week diving the southwest corner of Western Australia, concentrating on the state’s two largest cities – Perth and Bunbury. Our first stop was Perth, the most isolated capital city in the world.


Perth is one of the prettiest cities in Australia, sitting on the banks of the winding Swan River and renowned for its beautiful beaches. But for the diver the city has countless shore and boat diving options around rocky headlands, jetties and many offshore reefs and islands. For our first day of diving we headed south of the city to dive some of the jetties in Cockburn Sound. This large bay starts at the mouth of the Swan River off Fremantle and extends south to Rockingham, and protected to the west by Garden Island, has dozens of sheltered dive sites, many of which could best be described as muck sites.


It was hard to miss our first dive site as the Kwinana Grain Terminal Jetty is huge, around 300m long. We parked in the convenient carpark next to the jetty, geared up and then trudged across a beautiful white sandy beach and into the calm clear waters of the Indian Ocean.

I quickly found a very unique local species, a lovely pink sea cucumber. Now most sea cucumbers are not very exciting and easily overlooked, but this one was a pretty pink colour and was feeding, with its bushy arms collecting food and funnelling it into its mouth. I shot numerous photos of this colourful sea cucumber, and then looked up to see dozens of them all around me, and most more colourful than this one.

We then slowly swam from pylon to pylon, finding them covered in ascidians, soft corals, algae and sponges. On these pylons were crabs, nudibranchs, sea stars, blennies, porcupinefish, cowfish, leatherjackets and morwong.

There was an endless supply of unique West Australian subjects for my camera – western gobbleguts, western rock scorpionfish, western smooth boxfish and western striped cardinalfish – in fact lots of species with western in their name. Every second hole seemed to be occupied by a gloomy octopus and we also encountered over a dozen giant cuttlefish.

I spent most of my time with my head down looking for critters, but often looked up to find myself surrounded by schools of yellowtail, trevally and juvenile samsonfish. There were also many unexpected surprises, like several large tube anemones, a southern eagle ray grubbing in the sand and a pair of mating blue-swimmer crabs.

Almost an hour into the dive I finally found one of the local endemic species I hoped to see, a beautiful West Australian seahorse. This one was white in colour, with pretty wavy black lines on its snout. By the end of our two hour long dive we had found three more of these exquisite seahorses, another white one, plus a brown one and a purple one. We had an amazing muck dive, going no deeper than 9m and only exploring the first 100m of this huge jetty.

After lunch we headed to the northern end of Cockburn Sound to explore the Ammo Jetty. This small concrete jetty is not as visually impressive as the Grain Terminal, but its pylons were even more colourful, covered in beautiful telesta coral. We thought these jetties would be similar, but soon noticed a different range of fish and invertebrates. A big standout was the dragonets, they were everywhere. The most common species was the longspine dragonet, endemic to this region, but there were also finger dragonets and painted stinkfish (an Aussie term for some dragonets, as they do have slimy smelly skin).

Over a two hour long dive we encountered a wonderful range of endemic reef fish – boxfish, cowfish, leatherjackets, cardinalfish, triplefins, toadfish, blennies and two more West Australian seahorses. Colourful nudibranchs and flatworms were abundant, and I even found a sea hare. These two magic shore dives were a great introduction to the Perth area.



The next day we headed offshore to dive Perth’s main dive attraction, Rottnest Island. Located 18km offshore, Rottnest Island is a major tourist attraction, well known for its cute quokkas. However, this 10km long by 4km wide island is surrounded by countless limestone reefs, offering endless diving possibilities. We booked two days with Lionfish Charters, that operate the well-equipped Lionfish IV dive boat.

Over the years I have been on many day boats, but Lionfish IV is easily one of the best. This 24m long boat is surveyed for 40 divers, has three levels, a comfortable saloon, a huge dive deck and easy access in and out of the water. But one of the highlights, apart from the diving, was the food – breakfast when you arrive, an incredible smorgasbord lunch and finished off with desserts on the way home. I would be as big as a house if I dived from this wonderful boat each weekend!

Lionfish IV is owned and skippered by Andrew McGuckin, who has been diving the Perth area for 25 years and has hundreds of local dive sites to choose from. For our first dive Andrew took us to the northwest end of the island to dive a site called The Slot.

Andrew picked this site as I said I would like to see one of the unique wobbegong shark species that are only found in Western Australia. Nine of the twelve known species of wobbegong are found in Western Australia, and several of them are endemic. Unfortunately, they are also much shier in the west, hiding out in caves and ledges.

Anchoring up, conditions were not the best, overcast and a large ground swell, the result of an unseasonal storm several days before. We followed Andrew across a field of kelp to a large recess in the reef at 8m. He pointed out a small hole and then plunged in. I followed, which was hard work with the powerful surge. Andrew shone his torch about, pointing out crayfish and other critters in the dark until he found the resident western wobbegong. The wobby was very annoyed by the attention, and I only managed a few quick photos before it swam off and disappeared into another crack in the reef.

Andrew then led us to the main feature of this site, a massive limestone cavern hidden under the kelp. This huge cave was spectacular, with beams of light shining down from numerous small openings above and its walls and ceiling coated in colourful sponges, gorgonians, ascidians, soft corals and bryozoans. Schools of fish also flowed back and forth in the cave, including bullseyes, footballer sweep and gladius chub. It was a sight that no photo would ever do justice to.

We spent the next 30 minutes exploring this amazing cavern. A torch was needed to investigate the numerous holes, cracks and ledges, with almost every one home to a crayfish. We also spotted a green moray, a smooth stingray, marblefish, leatherjackets and dozens of southern blue devilfish. A highlight for me were two special west Aussie fish, the white-barred boxfish and the red-lip morwong.

Our next dive at Kingston Spit was a lot less surgy, but also featured caves, ledges and numerous fishes. Schooling fish were everywhere at this site, including old wives, bullseyes, pomfred, trevally and buffalo bream. Some of the unique west Aussie fish at this site included a harlequin fish and a striped stingaree.


The weather improved the next day, allowing us to dive one of the areas signature dive sites, the Shark Cave. This cave is actually a giant swim-thru, covered by a large slab of rock and sloping from 15m to 24m. Entering the cave I was ready to see sharks, but was first stunned by the colours and the fish life. Every available surface in this cave is covered in colourful sponges and ascidians, and swarming from floor to ceiling was a dense school of bullseyes and footballer sweep. And swimming between these fish were six grey nurse sharks!

The sharks were unconcerned by our presence, and continued to patrol the cave. I settled on the bottom to watch and photograph them, and was quickly rewarded with one shark angling in towards me. The curious 2m long shark slowly glided by, its small eye peering into my soul. Over the next few minutes the shark did two more close passes, before joining its brethren. We could have spent the entire dive in this cave, but exploring the rest of this rocky reef found numerous reef fish, dozens of crayfish and a southern eagle ray resting on the bottom.

Our final dive at Jacks Patch was also wonderful, with more ledges, caves and unique West Australian species to be seen. We could have easily stayed in Perth for several more days to further explore the incredible reefs of Rottnest Island, but we had more to see in the great southwest.



The next day we headed 170km south to Bunbury, the second largest town in Western Australia. A busy port town, but also a popular holiday spot, Bunbury is most famous for its resident bottlenose dolphins that visit Koombana Bay to be hand fed. While you can do dolphin tours, and even swim with the dolphins, we were more interested in Bunbury’s other underwater attractions.

Over the next three days we explored the areas rocky reefs and an artificial reef with Octopus Garden Dive Charters. Owned and operated by Kim Royce, who is quite a colourful character with plenty of salty tales to tell, Kim operates the 12m long vessel Cross Country.

Diving midweek, Stuart and I were the only divers and Kim suggest we first dive the areas most famous dive site, the Lena. Leaving the harbour, we were quickly joined by a pod of friendly dolphins that rode our bow for ten minutes. Thirty minutes later we tied to the mooring at the Lena.

Scuttled in 2003, the Lena was a 55m long fishing vessel that was captured by the Australian Navy illegally fishing in the Southern Ocean. Striped and cleaned, the ship now rests in 18m and is a brilliant artificial reef. We followed the mooring line to the bow of the Lena, then dropped to the sand to find sponge gardens and seagrass beds around the ship. We then did a slow circuit around the ship, finding cuttlefish, octopus, a sparsely-spotted stingaree, nudibranchs, southern blue devilfish and many other temperate reef fish.

We stopped at the stern to investigate the prop, now covered in sponges. Then returning down the starboard side found a large school of porcupinefish and moonlighters just hanging in mid-water. It was then time to explore the ship, which is completely encrusted with sponges, soft corals and algae. On the bow sit several winches, which are home to leatherjackets and wrasse. The bridge is a haven for thousands of bullseyes, while the kingpost swarms with blackhead pullers.

After a circuit of the deck, we dropped into the holds and explored the lower levels of the ship - into the engine room, along a conveyer belt and into the freezer rooms. The wreck itself is fascinating to explore, but it was the fish life that most impressed – schools of bullseyes, trevally and batfish, plus West Australian dhufish, boxfish, western talma, footballer sweep, morwongs, baldchin gropers and many other species.


We then dived the nearby Lena Reef, which is typical of the inshore limestone reefs off Bunbury, a series of rocky ledges only one to two metres high. This rocky reef is covered in seagrasses, sponges and plate corals, a very unique terrain. We found numerous giant cuttlefish, southern blue devilfish, leatherjackets, bullseyes, wrasse and boxfish. There was also a good collection of sea stars, sea cucumbers and crayfish to be seen.

Over the next two days we returned to the Lena two more times and also dived several more inner reefs. We had hoped to dive some of the outer reefs off Bunbury, that lie 15 miles offshore in 30m to 36m of water and are covered in blade corals and schooling pelagic fish, but unfortunately the offshore winds made this impossible. But the inner reefs were full of surprises.

At Peters Reef we found the Glauert’s frogfish mentioned in the introduction. Many unique and endemic frogfish are found in Australia’s temperate seas, however finding them is the big challenge. At Gibbs Reef we found bommies covered in beautiful small gorgonians and another unique local, a masked stingaree. While at Trevors Reef we were impressed by the nudibranchs and other sea slugs.

Our week diving the great southwest introduced as to some amazing dive sites and many wonderful local species, we just wish we had allowed a month to properly explore this fascinating and unique part of Western Australia.



Getting There

Many airlines fly into Perth, via Asia and the Middle East. Internal flights in Australia are available on Qantas, Virgin and Jet Star. To get to Bunbury a hire car is the best option, but it is also possible to catch a bus or train.

Accommodation & Diving

A wide range of accommodation can be found in both Perth and Bunbury. Perth also has a number of dive shops where you can hire dive gear. We dived Rottnest Island with Lionfish Charters that operate most weekends and midweek on demand. Octopus Garden Dive Charters ( offer dive charters off Bunbury and can supply hire gear.

When to Go

It is possible to dive Perth and Bunbury year-round, but the best conditions are found from October to May. The water temperature in both areas varies from 23°C in summer to 17°C in winter. The visibility in Cockburn Sound is usually around 6m to 12m and at Rottnest Island and Bunbury 12m to 20m, but it can vary from 6m to 30m.