Researchers have found the first underwater Aboriginal archaeological sites.

Aboriginal artefacts have been discovered off the Pilbara coast in Western Australia, representing Australia’s oldest known underwater archaeology.

The discoveries were made through a series of archaeological and geophysical surveys in the Dampier Archipelago, as part of the Deep History of Sea Country Project, funded through the Australian Research Council’s Discovery Project Scheme.

The two underwater sites date back thousands of years to when the current seabed was dry land. Investigations have already yielded hundreds of stone tools made by Aboriginal peoples, including grinding stones.

The two sites at Cape Bruguieres and Flying Foam Passage represent what is known today as Sea Country to many Indigenous Australians, who have a deep cultural, spiritual and historical connection to these underwater environments.

“Today we announce the discovery of two underwater archaeological sites that were once on dry land. This is an exciting step for Australian archaeology as we integrate maritime and Indigenous archaeology and draw connections between land and sea,” says Associate Professor Jonathan Benjamin from the the Maritime Archaeology Program at Flinders University.

“Australia is a massive continent but few people realise that more than 30 per cent of its land mass was drowned by sea-level rise after the last ice age. This means that a huge amount of the archaeological evidence documenting the lives of Aboriginal people is now underwater.

“Now we finally have the first proof that at least some of this archaeological evidence survived the process of sea level rise. The ancient coastal archaeology is not lost for good; we just haven’t found it yet. These new discoveries are a first step toward exploring the last real frontier of Australian archaeology.”

The dive team mapped 269 artefacts at Cape Bruguieres in shallow water at depths down to 2.4 metres below modern sea level. Radiocarbon dating and analysis of sea-level changes show the site is at least 7,000 years old.

The second site at Flying Foam Passage includes an underwater freshwater spring 14 metres below sea level. This site is estimated to be at least 8,500 years old. Both sites may be much older as the dates represent minimum ages only; they may be even more ancient.

The team of archaeologists and geoscientists employed predictive modelling and various underwater and remote sensing techniques, including scientific diving methods, to confirm the location of sites and presence of artefacts.

“At one point there would have been dry land stretching out 160 km from the current shoreline. That land would have been owned and lived on by generations of Aboriginal people. Our discovery demonstrates that underwater archaeological material has survived sea-level rise, and although these sites are located in relatively shallow water, there will likely be more in deeper water offshore” says researcher Chelsea Wiseman from Flinders University.

“These territories that are now underwater harboured favourable environments for Indigenous settlements including freshwater, ecological diversity and opportunities to exploit marine resources which would have supported relatively high population densities” says Dr Michael O’Leary, a marine geomorphologist at The University of Western Australia.

The discoveries were made by an international team of archaeologists from Flinders University, The University of Western Australia, James Cook University, ARA - Airborne Research Australia and the University of York (United Kingdom) in partnership with the Murujuga Aboriginal Corporation.

The experts say that the discovery of these sites emphasises the need for stronger federal legislation to protect and manage underwater heritage across 2 million square kilometres of landscapes that were once above sea level in Australia, and hold major insights into human history.

The study is accessible here.