Maritime archaeologists at Flinders University have produced a striking 3D reconstruction of Sydney Harbour as it appeared thousands of years ago, when sea levels were much lower than today.
The visualisations reveal a dramatically different scene: where the harbour's waters now shimmer, there once stretched a lush landscape of valleys, rivers, and dense vegetation.
Jamie Li, a Master's student in the Maritime Archaeology Program at Flinders University, combined his training in the archaeology of submerged landscapes with his expertise in 3D reconstruction to bring this long-lost world to life.
During the last Ice Age, global sea levels were up to 130 metres lower than today. Working with his supervisor Dr John McCarthy, Li developed a detailed model of the harbour as it would have appeared 10,000 years ago.
To build the reconstruction, Li digitally merged high-resolution sonar bathymetry (sea floor mapping) of Sydney Harbour's seafloor with a 'bare-earth' model of the modern city, removing all the buildings and infrastructure to expose the ancient terrain.
He then populated the landscape with soil, vegetation, and flowing rivers, creating an immersive and scientifically accurate image of a vanished pre-harbour landscape.
"The Sydney Harbour Bridge and Opera House are recognised around the world as symbols of Australia," says Li.
"But what fascinates me is what lies beneath them, a landscape that looked completely different tens of thousands of years ago. People don't realise how much the harbour has transformed, and I want to change that."
As glaciers grew and trapped water at the poles, Australia's Indigenous peoples lived through the dramatic lowering of the seas. The area we now know as Sydney Harbour would have been a series of deep, river-cut gorges leading to an ocean far to the east.
In Li's visualisation, ghostly silhouettes of Sydney's landmarks, such as the Harbour Bridge, show how modern and ancient worlds intersect.
The project was conducted in partnership with the Metropolitan Local Aboriginal Land Council. It reflects Aboriginal oral traditions, including Dharawal stories of the flooding of Botany Bay, which may preserve a memory of these changing sea levels over millennia.
Jordan Marr, Cultural Officer of MLALC says, "we think this is important because marine archaeology is the heartbeat of our submerged history.
"Each discovery a whisper from our ancestors calling us to remember who we are. By reclaiming these stories beneath the tides, we give the next generation of Aboriginal people the strength to walk forward with pride, carrying the wisdom of the deep into the light of the future."
Flinders University's Maritime Archaeology Program is internationally recognised for its research on submerged cultural landscapes. In 2019, the program identified the first published underwater Indigenous archaeological sites in Murujuga, Western Australia, a discovery that informed significant updates to Australian heritage management and legislation.
"During the last Ice Age, it would have been possible to walk from what is now Circular Quay to Luna Park without catching the ferry," says Dr McCarthy, Flinders' Maritime Archaeology Program Coordinator.
"We are all familiar with the threat to our modern cities from rising seas caused by human-driven emissions, but not everyone is aware of these much slower underlying natural cycles of sea-level change.
"The science tells us that there are likely to be traces of all types of Aboriginal archaeological features buried under the sediments of the harbour."
