This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In September 2026, 20 Australian university students departed Brisbane for Fiji aboard the CSIRO research vessel (RV) Investigator on a CAPSTAN sea training voyage. While in coastal waters off Queensland, the students were involved in several shipwreck surveys that led to an intriguing observation: A shipwreck surrounded by mysterious holes on the seafloor.
For some aboard, this wasn't the first time they'd seen such a thing. The CAPSTAN team was mapping the wreck of Althea II, a popular dive wreck lying in 40 meters (131 feet) of water off Bundaberg, Queensland, when they made the discovery. Lara Picton, an honors student studying geology at the Queensland University of Technology, described what they saw.
"It was really exciting to watch as we mapped the site in detail. What initially looked like a few depressions in the surface turned out to be far more widespread," Picton said. "The entire wreck is surrounded by an almost perfect circle of holes in the seabed, each typically 8 meters (26 feet) in diameter and 2 meters (7 feet) deep.
We identified around 300 holes, and they extend approximately 100 meters (328 feet) from the wreck in all directions and are the only features on an otherwise flat seafloor." Those aboard speculated that the source of the holes might be biological. A drop camera was deployed from RV Investigator to investigate further and collect footage to test this theory. The site was teeming with marine life of all shapes and sizes, including large fish such as rockcod.
The footage collected pointed to the holes being the result of bioturbation. Maddison Cross, a Ph.D. candidate studying marine biology at the University of the Sunshine Coast, explained how marine life can reshape the seafloor. "Fish, crustaceans and other marine life disturb the seafloor sediment as they feed, crawl, excavate and find things hidden in the seafloor and may also dig burrows to lie protected within," Cross said.
"The process of living organisms moving and mixing sediment is called 'bioturbation.' The organisms responsible act as ecosystem engineers and can dramatically alter the shape of the seafloor," she said. So why are the holes so similar in shape and size? Cross explained that it might be the result of the daily goings-on of life within the holes.
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