Published in Divelog Australasia August 2023

By Nigel Marsh

It is now five years since the retired navy landing heavy ship HMAS Tobruk was scuttled off the Queensland coast between Hervey Bay and Bundaberg. Over those years the ship has attracted marine life like a magnet, and it now swarms with reef fish, pelagic fish and a wide variety of invertebrate species. However, the ship has also been over-run by one unexpected species that now occupies almost every nook and cranny of the vessel – turtles!

The last time I dived HMAS Tobruk, two years ago, I was impressed by the volume of fish that call the site home and also by the lovely corals. One-metre-long spikey soft corals decorated almost every part of the 127m long ship, giving the impression that the ship had been underwater for over a decade, not three years. There was hardly a bare spot on the ship, as the decks, railings and fittings were covered in soft corals, algae, hydroids and sponges. On that dive I also saw two turtles, and they were very camera shy and swam off as soon as they spotted us.


I recently returned to dive HMAS Tobruk with dive buddy Brendon Harris. The weather was perfect, calm seas, light winds and blue water. Brendon is a local and dives the ship regularly and had informed me there were quite a few turtles now calling the ship home, but I wasn’t prepared for how many.

Descending on the stern we were greeted by fish. Massive schools of golden trevally, bludger trevally, barracuda, batfish, fusiliers and kingfish. We descended to the sand at 30m and under the stern were even more fish, including a dozen gold-spotted gropers, red emperors, mulloway, coral trout and masses of cardinalfish. After taking a few photos of the fish we then started to head to the bow, and this is where I saw the first green turtles.

Resting on the sandy bottom were at least four turtles. Some were just dozing on the sand, but others were tuck-up next to debris from the ship. They seem to be accustomed to divers as I managed to swim right up to the turtles to take a few photos. Continuing along the side of the ship (the top actually, as the ship rests on its starboard side) we saw more fishes, including angelfish, butterflyfish, coral snappers and tuskfish, and several more turtles. Near the bow we found several pink whiprays and a few large gropers, before ascending to explore the swallow port side of the ship on the way back to the mooring.


It was here that I realised that the ship was infested with green turtles, as they were everywhere. Lying on the handrails, on the deck, in the passageways and also on top of each other. As we swam the length of the ship, I estimated there must have seen over fifty green turtles, making this the greatest turtle dive I have ever done (and I have dived Raine Island, which is generally considered to be the greatest turtle dive on the planet).

It was great to see so many turtles, and I had a wonderful time photographing them. However, the sheer number of turtles has changed the ship completely since the last time I dived it. The turtles have either eaten or rubbed off most of the soft corals, sponges, hydroids and algae that once covered the ship. HMAS Tobruk now looks like it has only been down for weeks, as bare metal is exposed across many parts of the ship. It was quite surreal as the ship now feels like a newer wreck than when I first dived it.


On our second dive we saw just as many fish and turtles, enjoying 15m visibility as we explored the ship. We didn’t bother entering the ship, which has a lot of interesting penetration, as the schools of pelagic fish, the gropers and the turtles were the best subjects for our cameras. All the turtles were very chilled and great models for my camera, and while at times I could see six or eight turtles around me, the most I could get in one frame with my wide-angle lens was three. They all seem to like their own space, except for a few that were climbing on top of each other.

Seeing so many turtles on the one dive site was extraordinary. I hope next time I dive HMAS Tobruk there are just as many turtles, but I also wish they would let some of those lovely soft corals regrow.