In 2002, South Australia sank the ex-HMAS Hobart in less than 3 minutes; 18 years later, a marine survey recorded more than 50 species of fish around the destroyer.
A decommissioned 134-metre guided missile destroyer lying 30 meters below the surface of Yankalilla Bay has become one of South Australia’s most diverse marine habitats, less than two decades after it was deliberately sunk. The former HMAS Hobart was sunk on November 5, 2002. She sank in two minutes and 17 seconds after controlled explosives were detonated along her hull, according to the Naval Historical Society of Australia. A detailed scientific study carried out 18 years after the sinking found that the artificial reef was home to more than 50 different species of fish, along with large communities of filter-feeding marine organisms. The findings, published in reports from South Australia’s Department of Environment and Water (DEW), show how old military vessels can be repurposed to support marine life in areas of the seabed with few natural habitats.
Built by Defoe Shipbuilding Company in Michigan, United States, HMAS Hobart entered service with the Royal Australian Navy in December 1965. Over more than 35 years of service, the warship completed three combat deployments during the Vietnam War before being officially decommissioned in May 2000. Following her retirement, the Australian Department of Defense handed the ship over to the state of South Australia. The Fleurieu Artificial Reef Society and state authorities prepared the ship for sinking by removing hazardous materials, cutting off access points for divers and cleaning up fuel debris to ensure it was environmentally safe. When the explosives were detonated off the Fleurieu Peninsula, the ship sank upright on a flat, sandy seabed with few natural rock features. Its large steel structure, which included turrets, decks and accessible engine rooms, created vertical surfaces that changed the otherwise flat seafloor. These structures also intercepted nutrient-rich coastal currents, attracting organisms such as sponges, barnacles, and soft corals.
Scientific findings on reef colonization and species diversity.
The South Australian Department of Environment and Water’s Marine Sciences team carried out the biodiversity study using standard Reef Life Survey underwater visual census methods. Researchers recorded species such as snapper, southern blue devil fish, bullseye, and leatherjackets living in and around the wreck. The ship’s steel plates provide shelter from predators and strong tides, creating small habitats at different depths. The reef also benefits from legal protection under the state’s marine park system. The wreck is located within the Rapid Head Sanctuary Zone within Encounter Marine Park, where both commercial and recreational fishing is prohibited. According to Department of Environment and Water Management guidelines, rangers patrol the sanctuary to enforce no-take rules. This allows fish populations and organisms growing on the wreck to develop without the pressure of fishing and other forms of human extraction.
Ecotourism and the global network of artificial reefs
In addition to its conservation role, the former HMAS Hobart has become an important destination for experienced divers interested in temperate water wrecks. The site is unusual among Australia’s artificial naval reefs because divers have regulated access to parts of the ship’s interior, including the original engine room and missile areas. Australia has also sunk several other warships for similar tourism and conservation purposes, including the ex-HMAS Adelaide off New South Wales and the ex-HMAS Canberra off Victoria. International marine studies published in journals such as Ecological Engineering and Frontiers in Marine Science have found that well-managed steel shipwrecks can support similar numbers of fish and species diversity as nearby natural rocky reefs. By converting retired warships into permanent artificial reefs, environmental agencies can create long-term marine habitats while helping replace lost natural environments along developed coastal areas.
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