Australia’s Wild West – Mackerel Island

Australia’s Wild West – Mackerel Island

By Nigel Marsh
Mackerel Islands

The Mackerel Islands offer some of the most spectacular diving we have experienced in Australia.

The Mackerel Islands? Never heard of them!

Well neither had we until recently, but this group of islands, located in Western Australia, have just opened up to divers and are destined to become a diving hot spot.

The Mackerel Islands are located off the town of Onslow, some 16 hours drive north of Perth. We took the easy route to the islands, flying into Karratha then travelling 300km south to Onslow. From Onslow it is a one hour boat journey to Thevenard Island, where the Club Thevenard resort is located. This ex-mining camp is not the most luxurious of resorts, but it has opened up the Mackerel Islands to divers.

Arriving on Thevenard Island the first surprise was that the resort shares the island, and facilities, with Chevron Texaco, who have an oil storage operation on the island and several oil pumping platforms nearby. This is no tropical island paradise – the island is covered in low scrub. The accommodation and facilities are basic but comfortable; however this was no concern once we experienced the diving.

Our first few dives were on the reefs and bommies fringing Thevenard Island. At the East Coral Gardens, in only four metres of water, we explored the thick forests of hard corals that abounded with a surprising number of reef fish and invertebrate species. While at the Great Australian Bight we dived around numerous bommies in five to eight metres, encountering parrotfish, tuskfish, trevally, sweetlips, lionfish and Chinamen snapper. The bommies were covered in soft corals and gorgonians, which surprised us in this shallow water. We also found shrimps, crabs, crayfish, octopus, sea stars and a good range of nudibranchs. In fact nudies are a feature of the Mackerel Islands; we encountered them in large numbers and saw over twenty different species.

Mackerel Island

At Rob’s Bommie we investigated a series of large coral heads in only six metres of water. These were home to thick schools of sweetlips and snapper, but we also saw moray eels, gropers and several reef sharks. However the highlight was finding a two metre long tawny nurse shark resting under a ledge and just nearby two rarely seen northern wobbegong sharks.

Sultan’s Reef is a long reef that is largely unexplored – like most of the reefs in the Mackerel Islands. We dived a wonderful coral garden in 12m, seeing an incredible range of soft corals and gorgonians. Nudies were everywhere, and we also observed olive sea snakes, moray eels, flatworms, coral trout and a crocodilefish.

Trap Reef was even better. We did two dives here and explored caves, ledges and walls in only nine metres of water that were festooned with colourful soft corals. Huge numbers of reef fish darted about, as did gropers, reef sharks, coral trout and sweetlips. But the main feature was the macro life – nudies, flatworms, shrimps, crabs and even a juvenile batfish.

Greg’s Grotto was another colourful reef we explored that was riddled with caves and ledges, plus home to an astonishing range of reef fish, turtles, reef sharks, pelagic fish and invertebrates.

Black Flag is a small reef and the top dive site so far discovered at the Mackerel Islands. Seventeen metres deep, with caves, ledges and swim-throughs, this reef is covered in some of the most amazing coral growth we have ever seen; soft corals, sponges, ascidians, gorgonians and black coral trees. But you could almost miss this growth as you will be too busy looking at all the fish.

In two dives at Black Flag we saw staggering amounts of fish; schools of trevally, silver drummer, batfish, stripy snapper, mangrove jacks, rock cod, fusiliers, pearl perch, sweetlips, red emperors, gropers, coral trout and pufferfish, plus the usual collection of reef fish. Invertebrate species were numerous, but other highlights included white tip reef sharks, grey reef sharks, a tawny nurse shark, a tasselled wobbegong and several turtles.

This is one of the best dive sites we have ever done!

With much of the Mackerel Islands unexplored we did two days of exploratory diving. Now having done many exploratory dives in the past, and knowing that finding a good spot is pretty hit and miss, the five exploratory dives we did were all hit; well beyond expectations.

At Bessers Island we did three dives, the first at Tukula Corner saw us exploring bommies in 18m and encountering reef sharks, gropers, moray eels and a friendly potato cod. At North Ridge we explored a ledge at 14m that was home to gropers, reef sharks, moray eels, turtles and sea snakes.

While at The Scoops it was more of the same again, plus two mobula rays.

At Brewis Reef we found an amazing patch of bommies in only eight metres that were covered in colourful corals. We called the site Stonehenge and found wobbies, reef sharks, turtles and thick schools of giant trevally, snapper, surgeonfish and sweetlips.  But we saved the best until last.

On our last dive we explored a two metre high ridge of limestone we called Rankin Road. This ledge was 18m deep and filled with cardinalfish and home to gropers, white tip reef sharks, coral trout, stingrays, sea snakes and turtles. Schools of trevally and queenfish zoomed by, but the highlight was having 40 rankin cod, that had never seen a diver before, following us the entire dive. Simply amazing!

A week of diving the Mackerel Islands just whet our appetite for the wonderful diving in the area. One thing we should add, the area experiences very strong tidal currents, the reason the reefs are so rich, and the visibility is not always the best, averaging 12m-15m, but this is easy to put up with once you see the astonishing range of marine life to be found in this part of the Wild West.

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