For most of human history, the coastline has not been where it is today. That simple fact has enormous consequences.
During the height of the last Ice Age, vast quantities of water were locked away in continental ice sheets.
Global sea level was roughly 120 metres lower than today.
Where there is now ocean, there was once land. Not barren land. Grasslands. Forests. River valleys. Wetlands. Coastal plains.
And, almost certainly, people.
As the great ice sheets melted, the oceans rose and progressively swallowed enormous areas of this ancient landscape.
Much of it has never been systematically explored.
That raises an extraordinary possibility:
Could some of the most important chapters of human prehistory now be sitting beneath the sea?
The missing land
During the Last Glacial Maximum, roughly 26,000–21,000 years ago, sea level was dramatically lower than today.
The continental shelves were exposed. Britain wasn't an island in the form we know it today. The North Sea contained an enormous plain. Southeast Asia was connected by vast expanses of land that are now submerged. Australia and New Guinea were connected. Coastlines around the Mediterranean were considerably different.
The world's map was fundamentally different.
Then the climate warmed. Ice sheets melted. Sea level rose by roughly 135 metres between the Last Glacial Maximum and the mid-Holocene, according to palaeogeographic reconstructions.
The sea didn't simply rise around existing settlements. It transformed entire landscapes.
And eventually, some human settlements were submerged.
Doggerland: the lost world beneath the North Sea
For people in Britain, perhaps the most extraordinary example is Doggerland. Today, the North Sea separates Britain from continental Europe. But during the Ice Age, much of the area was dry land.
It formed a vast low-lying landscape connecting Britain with continental Europe. And humans occupied this landscape for thousands of years.
The archaeological evidence recovered from the North Sea includes stone tools, human remains, animal bones and other material demonstrating that the submerged landscape was once an important human environment.
The sea eventually won. But it didn't happen in a single dramatic flood. The landscape was progressively transformed as sea level rose.
New coastlines developed. Rivers were drowned. Lowlands disappeared. And eventually Britain became an island.
We are still finding pieces of Doggerland
The remarkable thing is that Doggerland hasn't vanished completely. Fragments of it still survive beneath the North Sea.
Peat deposits have been preserved beneath marine sediments. Ancient landscapes can sometimes be reconstructed from seabed cores. Archaeological objects have been recovered by fishermen and dredging operations.
And modern marine geophysical surveys are revealing features that would have been invisible to archaeologists working only on land.
A 2025 study using North Sea evidence from Doggerland produced a detailed sea-level record spanning approximately 13,700 to 6,200 years ago. It found two periods of accelerated sea-level rise, with rates reaching around 8–9 millimetres per year.
The same research describes Doggerland as a prehistoric landscape progressively submerged during the early Holocene.
The “lost land” is therefore not a legend. It is geological reality.
But what was actually lost?
This is where we have to be careful. There is a tendency to hear “submerged prehistoric landscape” and immediately imagine a lost city.
The evidence doesn't justify that.
Most of the people living in these environments were hunter-gatherers, fishers and later early farming communities.
Their settlements may have consisted of relatively small structures. Much of what they built would have been made from wood, reeds, hide and other organic materials.
These materials are difficult to preserve.
A settlement can therefore disappear far more completely than a stone monument. But that doesn't mean the society was insignificant. A small community can possess sophisticated knowledge of seasons, animals, plants, navigation, fishing, weather and landscapes.
Complexity doesn't necessarily require monumental architecture.
The coastline may have been especially important
There's another reason submerged archaeology matters. Humans have always been attracted to water. Rivers provide drinking water, coasts provide fish and shellfish and stuaries provide unusually productive ecosystems.
If prehistoric people behaved anything like later humans, some of the most attractive places to live may have been precisely the landscapes that were later drowned.
That creates a serious archaeological problem. The places most likely to have been heavily occupied are often the places we can no longer walk across.
Southeast Asia lost an enormous continent
The scale becomes even more dramatic in Southeast Asia. During the Ice Age, a vast region known as Sundaland connected areas that are now separated by shallow seas.
The modern islands of Sumatra, Java and Borneo were part of a much larger landmass.
The exposed continental shelf contained rivers, plains and other environments capable of supporting human populations.
As the ice melted, rising seas progressively fragmented this landscape.
A 2023 study reconstructed the changing geography of the region and estimated that Sundaland lost roughly half of its land area between the Last Glacial Maximum and the mid-Holocene.
That is extraordinary. Imagine removing approximately half of a vast inhabited region from the map. Not through war. Simply by allowing the ocean to rise.
Entire migration routes disappeared
The consequences weren't limited to individual settlements. When sea level rises, it can destroy connections. A valley that once allowed people to walk from one region to another can become an arm of the sea.
The same 2023 study found that rapid sea-level rises in Southeast Asia fragmented previously connected populations and were associated with major changes in human migration and population distribution.
So the drowned landscapes weren't merely places where people lived. They were potentially highways of prehistory.
Australia was once considerably larger
Australia provides another remarkable example. During the lower sea levels of the Ice Age, Australia was connected to New Guinea and Tasmania. The combined landmass is sometimes referred to as Sahul.
Humans occupied parts of this landscape for tens of thousands of years. When sea level rose, substantial areas disappeared beneath the sea.
Research into submerged landscapes in western Australia notes that roughly one-third of Australia's continental landmass was drowned by post-glacial sea-level rise.
That means an enormous portion of the landscape available to prehistoric Australians is now underwater.
Some of those drowned environments almost certainly contained human activity. The archaeological question is how much evidence remains.
And we are finding it
Underwater archaeology has already demonstrated that prehistoric landscapes can preserve archaeological evidence.
In western Australia, researchers have combined predictive modelling, airborne LiDAR, marine acoustics, coring and underwater investigation to search for submerged archaeological sites.
This is fundamentally different from traditional archaeology. The archaeologist isn't simply looking for a mound or stone structure.
They may first have to reconstruct an ancient landscape.
- Where was the shoreline?
- Where did the river flow?
- Where were freshwater sources?
- Where would people have been able to camp?
- Where would fish have been abundant?
- Where would a sheltered bay have existed?
Only then can researchers begin predicting where archaeological evidence might survive.
The Mediterranean has submerged settlements too
This isn't restricted to remote continental shelves. The Mediterranean contains known submerged prehistoric settlements. One of the best-known examples is Atlit-Yam, off the coast of present-day Israel.
The settlement dates to the late tenth to ninth millennium before present and lies several metres beneath the modern sea surface. It contains evidence of a permanent coastal community exploiting marine resources while also practising cultivation and animal husbandry.
This is important because it provides a real-world demonstration of the broader hypothesis.
A human settlement can exist beside the sea. Sea level can subsequently rise. And that settlement can end up underwater. We don't have to imagine the process. It has happened.
Some settlements may be almost invisible
The deeper we go into prehistory, the harder the evidence becomes to find. A modern city produces enormous quantities of durable material. An Ice Age camp might leave little more than:
- stone tools
- fragments of bone
- charcoal
- shells
- altered sediments
- wooden remains under exceptional conditions
- hearths
- footprints
- microscopic traces of activity
Now bury those remains beneath metres of sediment. Then expose them to waves and currents for thousands of years. Then send them beneath the sea.
The archaeological signal becomes extraordinarily difficult to detect.
The sea destroys — but sometimes preserves
There is an irony here. Water can destroy archaeological evidence. But underwater environments can also preserve things that would disappear on land.
Oxygen-poor sediments can protect wood, peat can preserve organic material, fine sediments can bury artefacts rapidly. Stable seabed environments can protect ancient surfaces.
This is why submerged archaeology can sometimes produce astonishing discoveries.
The problem is that finding the preserved material is only the first challenge. Researchers also have to establish exactly where it came from, how old it is and whether it remained in its original position.
What about the North Sea?
The North Sea may be one of the world's greatest underwater archaeological landscapes.
Its shallow seabed contains the remains of the former continental shelf. Peat layers preserve evidence of ancient wetlands. River channels can sometimes be reconstructed. Stone artefacts have been recovered.
And human remains have been discovered.
One remarkable North Sea discovery involved a human parietal bone and a decorated bovid bone from the Late Glacial period. Their recovery demonstrated once again that continental shelves can preserve archaeological evidence from landscapes that have since disappeared.
The seabed is therefore not simply an obstacle to archaeology.
It is an archive.
Could there be substantial settlements still undiscovered?
Yes. That is a very reasonable possibility. But the word “substantial” needs qualification.
There is currently no evidence demonstrating that large urban civilisations existed on the submerged continental shelves during the Ice Age. There is, however, compelling evidence that humans occupied extensive landscapes that are now underwater.
The unknown is how densely some regions were populated and how sophisticated their societies were.
And that is a question modern technology may gradually answer.
The technology is changing the search
Traditional archaeology begins with visible evidence. Submerged archaeology increasingly begins with mapping. Multibeam sonar can create detailed maps of the seabed. Seismic techniques can reveal buried sediment layers. Coring can recover ancient soils and peat. And magnetometry can detect anomalies associated with human activity.
Underwater excavation can then investigate promising locations.
Sediment dating can establish when landscapes were exposed and when they were submerged. And increasingly sophisticated computer models can reconstruct ancient coastlines.
The result is something approaching a time machine. Not one that physically takes us into the past, but one that reconstructs the geography of the past.
The disappearing coast
There is another important point. Sea-level rise didn't simply drown one prehistoric coastline. It drowned many.
As ice melted, the shoreline migrated inland. In some regions, this happened relatively slowly. In others, there were periods of rapid acceleration.
The 2025 North Sea study identified pulses of accelerated sea-level rise during the early Holocene, providing unusually detailed evidence of how quickly the coastline could have changed.
For a human community living beside the sea, this could have been transformative. A familiar shoreline might retreat, freshwater sources might become brackish. Fishing grounds would shift. Former settlements might become unusable.
Eventually, communities would have to adapt or move.
Did people remember the flooding?
This is one of the most tantalising questions. Human societies transmit memories through stories. Some cultures possess traditions involving great floods.
It is tempting to connect these directly with the post-Ice Age flooding of coastal landscapes. But we have to resist the urge to turn every flood story into a literal account of a prehistoric event. Flood myths can arise independently.
Flooding is a fairly common human experience. And stories change enormously through oral transmission.
There is currently no reliable method for proving that a particular ancient flood tradition preserves a memory of Ice Age sea-level rise.
But the possibility is intriguing. Humans were there. The sea really did rise. And people really did watch familiar landscapes disappear.
The biggest problem with the “lost civilisation” idea
The word civilisation can be misleading. If by civilisation we mean cities, writing, monumental architecture and complex states, there is currently no evidence that such societies existed on the submerged Ice Age continental shelves.
But if we use the word more broadly to mean organised human communities with sophisticated environmental knowledge, social structures, technologies and cultural traditions, then the situation becomes much more interesting.
We know such communities existed. We simply don't know how much of their world is now inaccessible.
We may be missing the coastal majority
Here's the bigger archaeological problem. For much of prehistory, coastal environments were highly productive. But the archaeological record we have today is heavily biased towards places that survived above water.
That means the surviving record may not represent where people actually lived most successfully.
This doesn't mean the missing areas did contain lost cities. It means our picture of prehistoric human settlement is inevitably incomplete.
A continent can disappear without leaving a continent-shaped clue
The most remarkable thing about submerged landscapes is that they don't necessarily look spectacular from the surface.
There may be no visible ruins. No giant walls. Just a seabed. But beneath that seabed could be an ancient landscape. A river channel, a buried forest, an old shoreline.
The clues may be microscopic. Yet together they can reconstruct an entire vanished environment.
What might we discover next?
The next major discovery may not be a spectacular underwater monument. It could be something much smaller. And that discovery could change our understanding of an entire region.
Because archaeology is cumulative.
One site tells us something. Ten sites tell us much more. A network of sites can reveal a civilisation or culture's landscape. And if those sites are connected by an ancient coastline, river or land bridge, the picture becomes much larger.
The real lost world
Perhaps the most important conclusion isn't that a mysterious advanced civilisation might be waiting beneath the sea. We don't have evidence for that.
The real lost world is something more certain. Ordinary human life, families, hunters, children, travellers. People adapting as the world around them changed.
Their world was real. Their landscapes were real. And much of that world is now underwater.
How much of prehistory is missing?
We don't know. But we can say something remarkable with confidence: a significant portion of the landscapes inhabited by Ice Age and early Holocene humans no longer exists above sea level.
The archaeological record we see on land is therefore only part of the story. The rest lies beneath oceans, seas and continental shelves.
Some evidence has already been recovered. Much more is likely to remain buried.
And perhaps the greatest discoveries will come not from looking further into the mountains or deeper into caves, but from looking down. Because the map of human prehistory is incomplete. And some of its missing pages may still be there.
The sea didn't erase the past.
It hid it.
Read more on:
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