Original subtitles

NARRATOR: Beneath the clear blue waters

of the Mediterranean lie treasures of ancient empires,

relics of their bloody wars,

and secrets of the seismic forces that shaped them,

lost beneath the waves...

until now.

Imagine if we could empty the oceans,

letting the water drain away

to reveal the secrets of the seafloor.

Now, we can.

Using the latest underwater scanning technology,

piercing the deep oceans,

and turning accurate data into 3D images.

This time, what apocalyptic disaster

triggered the collapse of Europe's first civilization?

Can an extraordinary 2,500-year-old shipwreck

unlock the secrets of Ancient Greece?

How did these deadly objects

turn Ancient Rome into a superpower?

And why does the Sin City of the Roman Empire

lie abandoned beneath the waves?

(music)

(music)

(music)

Ancient people call it the Middle Sea,

the center of the known world.

The Egyptians, Greeks and Romans

build mighty civilizations upon its shores.

Empires battle for supremacy across its waters.

Cities grow rich and powerful through trade.

The Mediterranean becomes a superhighway,

connecting cultures that will shape the modern world.

But only by draining the sea can we reveal

its biggest and most terrifying secret.

What happened on this spectacular Greek island

to doom an entire civilization?

COSTAS SYNOLAKIS: They must have thought this was it,

the end of the world.

NARRATOR: 3,600 years ago.

15 centuries before the Roman Empire.

A mysterious people dominate the Mediterranean.

We call them the Minoans.

Their home is on Crete.

Here they build magnificent temples and palaces,

and decorate them with stunning frescoes.

Celebrating their love of life and of nature.

But there's a darker side, too.

The Minoan royal palace at Knossos

is said to contain a labyrinth.

Home to the Minotaur.

A fearsome creature...

part man, part bull,

with a terrible appetite for human flesh.

But apart from a grisly myth,

much about the Minoan world still remains a mystery.

MICHAEL SCOTT: We can't decipher their language.

We only have their archaeological remains,

but what that tells us, I think,

is that they were extremely imaginative,

they were extremely adventurous,

and that they developed

a sophisticated hierarchical society

that was capable of producing elements of art and architecture

which still astound us today.

NARRATOR: Historians do know that the Minoans spread

across the Mediterranean,

trading olive oil and pottery for gold and ivory,

growing ever richer and more powerful.

And then, in the 15th century BC,

their ancient civilization begins to fade

from the pages of history.

For centuries, no one knows why.

Until scientists start to look closely

at the nearby island of Santorini.

SYNOLAKIS: Santorini, it has this very, very calm water.

It's almost like it plays with you and deceives you.

Looking at this view, you would never imagine

how dangerous it once was and how dangerous it is.

NARRATOR: The island is famous

for its spectacular, jagged cliffs,

which tower above a beautiful natural harbor.

But what created them?

And can they help explain the downfall of the Minoans?

Marine geologist Evi Nomikou believes that crucial clues

may lie deep beneath Santorini's tranquil waters.

EVI NOMIKOU: As I was born in Santorini,

I wanted to study the area to reveal their secret.

Being a marine geologist means that you're having access

to the mystic world of the seafloor,

so you can see features that nobody else can see.

NARRATOR: She harnesses the latest

multi-beam sonar technology

to scan the depths of the huge bay.

By transforming her data into powerful computer imagery,

it's possible to drain away the waters of the Mediterranean...

(music)

...and reveal Santorini's terrifying secret.

The sheer cliffs tower 1,000 feet above sea level

and drop a further 1,000 feet to the seafloor.

Framing a vast basin

large enough to hold 10,000 Olympic stadiums.

The basin is a huge crater,

and Santorini itself is the remnant of a gigantic volcano.

(music)

But that's not all.

On the rim of the crater,

more evidence of Santorini's violent past.

(music)

(screams)

Undiscovered until 1967,

these shattered ruins are all that remain

of a once-thriving city,

known today as Akrotiri.

It was destroyed when the volcano erupted,

and buried under so much ash that it remained hidden

for 3,500 years.

LEFTERIS ZORZOS: It's almost like a window back in time,

where you can see how it was when it was destroyed.

NARRATOR: And deep in the ruins

archaeologists discover something remarkable.

(rumbling)

These stone steps were not broken

by the ash and lava from a volcano.

(rumbling)

They were shattered by an earthquake.

ZORZOS: When the earthquake happened,

everyone fled their town,

but then they came back to start rebuilding their homes,

and this is exactly what we're seeing here.

NARRATOR: Believing the danger over,

people move furniture into the streets,

so they can start repairing their houses.

ZORZOS: We're seeing the beds placed outside of their homes,

we're seeing the stones and mud

getting ready to be used to rebuild these homes.

NARRATOR: But then they are struck by an apocalypse.

(rumbling)

(explosion)

The first stage of the eruption is so powerful

that it engulfs Akrotiri

and suffocates the whole island in a thick layer of debris.

And the date of this cataclysmic eruption?

Around 1625 BC, the same time as the Minoans

begin to disappear from the pages of history.

But how could a single eruption trigger the collapse

of a great civilization based on an island 70 miles away?

Until recently most scientists have focused

only on the evidence above ground.

But Evi Nomikou believes that once again

the real clues lie underwater.

EVI NOMIKOU: Scientists have been occupied

studying only the on-land geology,

so we are starting mapping the seafloor,

in order to find out the total volume

of that big, destructive eruption.

NARRATOR: Evi heads outside the great crater

to hunt for new evidence on the seabed.

And what she finds is extraordinary.

Proof of the sheer scale of this eruption.

As the waters of the Mediterranean recede

still further, they reveal wide stone terraces,

fanning out from the mouth of the volcano...

the size of 20-story buildings.

They point to one cause.

They're called pyroclastic flows:

torrents of superheated gas and molten rock.

NOMIKOU: The pyroclastic flow can cover everything.

They travel like a hurricane.

They can destroy everything on their path

because of the high temperature, up to 1,000 Celsius.

NARRATOR: When they hit the sea,

the pyroclastic flows cool and become solid ramparts of rock.

Around Santorini, they stretch for a staggering 20 miles

in every direction.

Evidence of multiple eruptions lasting for days.

By measuring the stone terraces,

scientists calculate that the volcano throws out

14 cubic miles of debris.

An eruption far more powerful than they had ever imagined.

It's one of the biggest volcanic explosions

in the history of the planet.

(explosion)

SYNOLAKIS: Let's try to imagine what this eruption looked like.

If you were sitting somewhere in any of the neighboring islands,

it would have appeared like the end of the world.

NARRATOR: At first the volcano blasts out

a column of superheated debris more than 20 miles high.

SYNOLAKIS: This huge funnel of black ash and cloud

could have been seen going all the way to the sky.

NARRATOR: Some of the volcanic plume falls to Earth

many miles from Santorini.

SYNOLAKIS: It would have been raining pumice

on the surrounding islands.

NARRATOR: But now the volcano unleashes

its most devastating surprise,

and in its path lies Crete, the center of the Minoan world.

NARRATOR: 70 miles from Santorini,

the Minoans on Crete see the soaring column of ash and smoke

from the erupting volcano.

But they have no idea of the disaster to come.

The volcano blasts millions of tons of lava into the sea.

Triggering wave after wave of powerful tsunamis.

SYNOLAKIS: When the tsunami arrived in Crete,

they were probably taken totally by surprise.

Imagine seeing this wall of water,

in some places ten meters high, advancing in.

It must have looked like this was the end of the world.

Totally unexpected.

The wrath of the gods.

NARRATOR: Entire coastal communities are swept away

by waves up to 30 feet tall.

Ports are destroyed and ships smashed to pieces.

And the gods aren't finished yet.

After the eruption and the tsunamis,

another disaster is looming.

Clouds of volcanic ash cast a deadly pall

over the whole Mediterranean, dramatically cooling the Earth.

SCOTT: There were a series of effects from the eruption

that together fatally weakened the Minoan civilization.

A tsunami event, a divine event.

The destabilization of their economy,

the failure of harvests over several years.

That was the moment when Minoan civilization started to die.

NARRATOR: Without their ports and ships,

the Minoans lose their mastery over the Mediterranean.

Invaders challenge their power.

And as the sun sets on the collapsing Minoan civilization,

new powers arise.

500 miles from Crete, just off the coast of Cyprus,

the draining waters of the Mediterranean

reveal a remarkable discovery almost 2,500 years old.

What can it tell us about the lives, the power,

and the pleasures of the Ancient Greeks?

In the centuries after the fall of the Minoans,

the city-states of Greece

produce dazzling art and architecture.

Forging ideas in mathematics, democracy and theater

that still shape our world.

The Greeks take to the sea in their wooden sailing ships

risking their lives to explore, colonize,

and trade with each other.

Hundreds of boats shuttle across the Mediterranean,

linking settlements in Africa, Asia and Europe.

They are the lifeblood of Greek civilization.

But these ships are a mystery.

Only a few remnants have survived to offer a glimpse

into how they worked and what they carried...

until now.

A shipwreck, recently discovered

in the seas off Cyprus,

is helping to bring this lost world back to life.

Archaeologist Stella Demesticha and her team

are unlocking the wreck's secrets.

Where did it come from?

What was it carrying?

And why did it sink?

STELLA DEMESTICHA: It's pretty deep, so it takes a while

when you're diving before you can see the sea bottom.

SCOTT: It looks all very higgledy-piggledy,

it looks like, well, someone's dropped a whole load of garbage

in the ocean.

NARRATOR: But this apparent chaos is packed with clues

about the lost world of the Ancient Greeks.

DEMESTICHA: This is really fantastic for an archaeologist.

NARRATOR: Exploring such a deep and complex site

is challenging.

DEMESTICHA: Diving at 45 meters has several constraints,

and time is one of them.

The maximum we can stay per day is 20 minutes.

NARRATOR: It's almost impossible to work effectively

at such depths.

So the team explores the site

using a technique called photogrammetry,

taking hundreds of pictures of the wreck

from different angles.

DEMESTICHA: So instead of trying to make decisions at 45 meters

where your brain doesn't work properly,

taking the pictures allows us to have the luxury

of diving through the screen of our computer

as long as we wanted.

NARRATOR: Using the unique photogrammetry data,

it's possible for the first time

to drain the Mediterranean...

allowing sunshine to illuminate a site that's been in darkness

for 2,500 years.

(music)

The debris lies in the shape of a ship.

Much of the timber hull has rotted away,

leaving only its ancient cargo.

Hundreds of earthenware jars, known as amphorae,

piled neatly on top of each other,

many of them still intact.

(music)

SCOTT: Amphorae look very odd.

They look very ungainly and not very well designed

to be storage jars or certainly container jars on a sea vessel.

But they are a design that's evolved over centuries.

And actually if you stack them all really neatly together,

they do all make sense,

and they were the way that you transported things

around the ancient world.

NARRATOR: Amphorae like this

give the archaeologists some vital clues.

Their distinctive shape varies,

depending on where and when they were made.

This one dates from the 4th century BC

and comes from the Greek island of Chios,

500 miles from the wreck site.

So what was in it?

Although the amphorae are all now empty,

they offer intriguing clues about what they once contained.

DEMESTICHA: In this case we have the opportunity to see evidence.

This dark coating inside the amphora,

we have to imagine that it was all over the inside walls,

and it was pitch, or resin,

so it was a kind of sealant to make these walls waterproof.

So we are sure that these are Chian wine containers.

NARRATOR: Wine from the island of Chios is highly prized

throughout the Ancient Mediterranean.

The wrecked ship is loaded with the equivalent

of more than 10,000 modern-sized bottles.

A hugely valuable cargo and a telling insight

into the Ancient Greek trade in luxury goods.

SCOTT: The Greeks loved their wine.

This little wreck off Cyprus

is the tip of the iceberg of the wine trade.

It was an absolutely fundamental part of their society

and of all their cultural experiences,

whether that be religious

or whether it be letting their hair down

and having a really good time.

DEMESTICHA: The greatest thing about Ancient Greeks

is their love for life.

They like to talk, to think, to discuss, to drink, to party.

SCOTT: There was a great profit to be made

in making sure that the rich around the Mediterranean world

had a good supply of very good wine to drink.

NARRATOR: Trading in wine and other luxury items

makes good money for the Greek city-states.

But their ships carry an even more precious cargo,

as they traverse the Mediterranean and beyond,

from Egypt to Southern France,

they spread Greek ideas and culture

that influence Western civilization

to the present day.

But this cargo never reaches its destination.

DEMESTICHA: One of the most important questions that we ask

in shipwreck archaeology is why this ship sunk.

NARRATOR: The biggest clue is the shape of the debris.

The way that the jars lie grouped together

rather than scattered about

proves that the vessel didn't capsize.

So what did happen?

DEMESTICHA: The ships in antiquity were open-decked.

The hold was not covered with a deck,

so when the waves were very high, or we have a storm,

then the water was coming in.

NARRATOR: The ship is most likely overwhelmed by a wave.

Pulled down by the weight of all the expensive wine

to a watery grave.

(music)

(music)

(music)

As the waters of the Mediterranean

continue to drain away,

they uncover unique evidence of a titanic clash

between two ancient superpowers.

This is the site of a battle

that would change the course of history.

WILLIAM M. MURRAY: When they saw the Romans in front of them,

they had one of these 'Oh, no!' moments.

NARRATOR: What can these bizarre objects on the seabed

tell us about the merciless rise of the Romans?

NARRATOR: The third century BC.

Rome already controls mainland Italy,

and has ambitions to expand across the whole Mediterranean.

But its navy is weak.

JON HENDERSON: Rome was known as being a terrestrial power,

not a maritime power, it was not known for fighting sea battles,

but they were set on a militaristic path

of maritime control.

NARRATOR: This brings them into conflict

with another superpower of the Mediterranean:

the Carthaginians.

SCOTT: The Carthaginians were great traders, great seafarers,

controlling most of the west and central Mediterranean,

and it was that fact

that brought them into conflict with Rome.

NARRATOR: Carthage, from its position

on the north coast of Africa,

commands the most powerful navy in the region.

To challenge Carthage,

Rome must first learn a new kind of naval warfare.

So begins a titanic struggle

that will last for more than 100 years.

The winner will dominate the Mediterranean

for the next seven centuries.

Its first truly decisive encounter happens

somewhere off the west coast of Sicily,

near the Egadi Islands.

Here, according to ancient historian Polybius,

the mighty navies of Rome and Carthage

go head-to-head in an epic battle.

He describes the clash of two huge fleets

involving 400 ships, and at least 100,000 men...

turning the waters of the Mediterranean blood-red.

But Polybius writes his history

at least half a century after the battle

and for a Roman audience.

So how reliable is his account?

However huge this battle may have been,

no one has ever been able to find any trace of it.

MURRAY: Taking the description from an ancient historian

and actually pointing to the exact place

on the surface of the globe where the battle took place

is extremely difficult.

NARRATOR: Bill Murray and a team of marine archaeologists

are on the trail of some extraordinary finds

reported by local fishermen.

But the area they need to survey is huge,

many miles across.

So first, they sonar scan the seabed.

Then they launch a remotely operated vehicle

to investigate the finds.

(music)

(music)

PETER CAMPBELL: As you're watching the live feed

of the video from the ROV, and it's going across the seafloor,

the shapes suddenly pop into view,

and it's incredibly distinctive.

So there's a great moment of excitement

as these objects are first seen.

NARRATOR: They discover a truly astonishing shape

300 feet down.

CAMPBELL: These are the rarest artifacts

we have from antiquity.

NARRATOR: So what is it?

Using the data gathered by the expedition,

it's possible to pull the plug on the Mediterranean,

emptying the waters from around the coast of Sicily.

The mysterious object on the seabed comes clearly into view.

It's three feet wide and made of metal.

Its jagged edges suggest a deadly purpose.

SCOTT: So these are bronze battering rams.

They would have been attached to the front of a ship,

and this was the main method

of attacking and destroying ships in antiquity.

NARRATOR: Rams are the superweapons

of ancient naval warfare.

The large vertical fin is like a splitting axe,

and the horizontal fins are like blades,

to slice through an enemy ship's timbers.

SCOTT: You didn't have cannon fire,

there were no kind of guns a la Pirates of the Caribbean

or anything like that.

The only way to take down the enemy ship

was to smash a massive hole in the middle of it

and let it sink to the bottom,

and the only way of doing that was to ram it.

(crashing)

NARRATOR: A closer look reveals

that this ram is battle-damaged,

its metal edges broken and distorted

by a violent collision.

MURRAY: In one episode

we're told that the men up in a forward tower

were literally catapulted out of the tower

and into the sea after a ram strike.

And we're told that it was an effective ram strike,

because as the ancient author wrote, 'Bronze hit bronze.'

NARRATOR: And this isn't the only discovery.

Based on data from the survey,

draining away more of the Mediterranean

reveals a remarkable pattern.

Ten more rams, scattered

across two square miles.

More than enough to convince historians

that an important naval battle took place here.

But is it the legendary Battle of the Egadi Islands

described by Polybius?

An unlikely piece of evidence may hold the answer.

A single amphora storage jar, found near one of the rams.

By analyzing its shape

archaeologists can narrow down when and where it was made.

It's like finding a black box recorder.

The team believes the amphora is Carthaginian

and dates to the 3rd century BC,

the same period as the Battle of the Egadi Islands.

The historian Polybius describes how the Carthaginians

are carrying supplies for their soldiers in Sicily.

Could this amphora be part of that cargo?

POLYBIUS: The plan was to cross to Mount Erice,

unobserved by the enemy, and offload the stores.

Then take on soldiers in the lightened ships

and engage the enemy.

NARRATOR: But the Carthaginians never make it.

Compelling evidence from the drained seabed

now indicates this is where it all happened.

MURRAY: A number of rams line up and give us a bearing

that makes some sense,

and that's fascinating, that is exciting.

NARRATOR: The words of an ancient historian

and the evidence of modern technology

both point to the same conclusion:

this is the site of the Battle of the Egadi Islands.

MURRAY: It was an important enough event for the Romans

that they remembered the date.

It was actually written down in a calendar somewhere,

and we know that it occurred on 10 March, 241 BC.

This is not your typical naval battle where both sides prepare.

This was a battle of opportunity.

NARRATOR: The Carthaginians, still laden with supplies,

head for shore believing the coast is clear.

But the Romans keep dozens of their ships hidden

behind one of the islands.

It's a huge ambush.

MURRAY: The lookouts spied the Carthaginian ships coming in,

and as the Carthaginians saw the Romans in front of them,

they had one of these 'Oh, no!' moments.

CAMPBELL: So we're talking about tens of thousands of men

on board these ships,

and they would have lined up across from each other

in lines of battle,

headed toward each other at a great rate,

and smashed into each other head-to-head.

(crashing)

(men yelling)

NARRATOR: Polybius describes what happened next.

POLYBIUS: Before long, they were defeated.

50 of the Carthaginians' ships were sunk,

and 70 captured with their crews,

while the prisoners numbered almost 10,000.

NARRATOR: Another discovery on the seabed is a stark reminder

that this epic victory came at a high price in human life.

This is the last resting place of thousands of brave men.

And it has been judged so important

that its exact location must remain secret.

CAMPBELL: There's nothing else really like this.

It's the first ancient battle site

that's ever been discovered.

It's just an incredible debris field.

SCOTT: The Battle of the Egadi Islands was the turning point,

when a Roman fleet managed to absolutely trounce

a Carthaginian fleet at sea.

CAMPBELL: This was the defining battle

where Rome went from a regional power to a superpower.

NARRATOR: The struggle between Rome and Carthage

would last for another century.

But victory here set Rome on a path

to shaping the destiny of Europe for the next 700 years.

As the last of its water runs away,

the Mediterranean reveals a final secret.

What can draining the Bay of Naples teach us

about the glory and the decadence of the Roman Empire?

NARRATOR: 2,000 years ago

Rome has grown far beyond its Italian homeland.

Its legions control a vast area

from North Africa to Northern Europe,

from Spain to the Black Sea,

and the Roman navy dominates the Mediterranean,

from its port next to the city of Baiae

in the shadow of mighty Vesuvius.

Baiae earns a reputation as the Sin City of Ancient Rome.

It's famous for debauchery and excess.

But what really went on in this seaside party town?

And why does so much of it lie abandoned beneath the waves?

Now, marine archaeologist Jon Henderson is exploring

the secrets of this sunken city.

Starting with the huge harbor walls

that once surrounded the city's port.

HENDERSON: These are built by the Romans.

They were incredible engineers.

You can still see the artificial construction

of this very clearly.

You can see the brickwork, overlapping bricks.

Amazing!

NARRATOR: Beyond the port walls lie magnificent villas

where Roman emperors host lavish parties.

HENDERSON: Look at this.

This is a mosaic floor of one of the bath houses.

Looks like it was just done yesterday.

It's phenomenal!

Absolutely amazing!

This is called the nymphaeum.

It's actually an elaborate dining room

for the Emperor Claudius.

You can imagine people eating food

surrounded by these water nymphs.

It was built to entertain the emperor's most honored guests.

Well, one of the things I'm interested in

is actually the scale of the site.

Much of the focus has been on the resort area of Baiae itself.

But on the margins of the site

there are constantly new areas coming up.

(music)

That's it, slow it down.

There's a lot down there.

NARRATOR: So why did the Romans lavish so much wealth

on building a pleasure city here?

HENDERSON: The Romans came to Baiae

because of the lovely maritime climate and the thermal springs.

But Baiae was also a very important port,

it's a natural port,

it's one of the best ports

on the western coast of Italy at the time.

NARRATOR: Wealth brought pleasure and excess

to this Las Vegas of the Roman world.

HENDERSON: There were parties, there was drinking,

it was a place to get prostitutes,

and writers at the time referred to it as 'a harbor of vice'

or 'a vortex of luxury.'

NARRATOR: The famous Roman philosopher Seneca

is appalled by what he finds.

SENECA: Baiae is a place to be avoided.

People wandering drunk along the beach,

the riotous reveling of sailing parties,

the lakes noisy with singing.

NARRATOR: But time is running out for this party town.

Gradually many of its most impressive public buildings

and private villas are lost beneath the waves.

What happened?

Based on detailed sonar scanning,

draining away the Mediterranean begins to reveal the real story

of the rise and fall of Baiae.

It exposes just how much of the city fell under the waves.

430 acres of streets, shops,

warehouses, and luxury villas.

Draining beyond the town uncovers the reason--

an extraordinary landscape,

shaped by powerful underground forces.

The whole town sits inside the shallow crater

of a giant volcano.

HENDERSON: You hear about Naples,

people talk about Vesuvius, they don't seem to realize that

the whole western Bay of Naples itself is a massive volcano.

We're actually standing in a volcano now.

NARRATOR: The people of Baiae may not understand

the unpredictable forces stirring beneath them.

DOUGAL JERRAM: And we know we're sat on a volcano.

But it's not your normal volcano.

It's this much larger and much more complex volcanic system.

NARRATOR: There's remarkable evidence of its restless power

three miles away, across the bay in the Temple of Serapis.

JERRAM: It's really when you get into the Roman ruins

that you can see what's going on.

You have to look closely, though.

If you look up at the column behind me,

you'll see in the middle part

it's got this strange texture to it.

Lots and lots of holes in it.

There's even bits of shell on this.

This is a stone-boring marine mollusk.

That tells me that this stuff has been under the sea.

Time enough for those mollusks

to get to grips with the columns.

But look now, these columns are in place,

and look where those marker horizons are now.

That's like a tide on the side of a bath

telling you where the sea level was.

So we know that this has been dropped under the sea,

and it's now risen above.

NARRATOR: Can draining the waters of the bay

even further explain why this ancient landscape

is constantly rising and falling,

and finally show why the Romans lost their Sin City?

NARRATOR: Baiae, once a major Roman port,

lies half-submerged amid a volcanic landscape.

(music)

Jon Henderson has been exploring the area

beneath the waves,

and he finds a telltale sign of the power at work here.

HENDERSON: So we've got all these bubbles

are coming out of the ground,

all this hot air coming up from the seabed.

You really get a sense here of the power that's underneath,

waiting to burst out.

Hot water piling out of the ground under the sea.

I've never seen anything like this.

NARRATOR: These underwater vents are superheated

by molten rock from the volcano below,

evidence that the forces stirring under Baiae

are highly active.

Locals call the area Campi Flegri,

the Fields of Fire.

Now, for the first time, draining the water

from the entire bay exposes an extraordinary site.

24 separate volcanoes nesting inside the crater.

It spans an incredible 38 square miles.

But geologists here have been mapping

deep inside the Earth itself.

Now, draining not only the Mediterranean,

but looking deep into the layers of rock below it,

reveals a fantastical sight.

Giant cauldrons of superheated molten rock,

known as a magma chambers,

that slowly empty and fill over centuries.

Evidence that this huge volcanic system

is still very much alive.

HENDERSON: Basically you've got magma chambers

sitting under the sea, which operate almost like bellows.

When they fill full of lava, the ground goes up,

and then when they empty again the ground goes down,

and this process is going on constantly.

NARRATOR: It's as if the land within the Campi Flegri crater

itself is breathing.

SCOTT: You feel like you're standing

on some kind of giant's chest.

You feel minute compared to the giant tectonic forces

that are creating the world around you.

NARRATOR: The damage caused

by these breathing chambers of magma

coincides with the decline of the Roman Empire.

As part of the city slides beneath the Mediterranean,

the population shrinks and the parties end;

Sin City is no more.

Today, the scientists studying the landscape here

believe that pressures in the magma chambers

are increasing once again,

and that could have catastrophic consequences

for the millions of people living close by.

JERRAM: We know it's an active system.

So one of the interesting problems we have

with something the size of Campi Flegri is,

is it going to erupt big or is it going to erupt small?

NARRATOR: Big could mean very big.

In AD 79, nearby Vesuvius erupts.

It destroys the city of Pompeii.

Thousands of people burn to death or choke on volcanic ash.

But scientists know the volcanic system

feeding the Fields of Fire is far larger

and far more powerful than Vesuvius.

And with so many people living nearby,

it's vital to keep a close eye

on the breathing giant beneath them.

JERRAM: It's even more critical

that we monitor volcanoes like this,

and that's because we're verging

on the side of what we call a supervolcano.

NARRATOR: Even the smallest changes in the ground level,

or its temperature, could be a vital warning sign

that the unstoppable forces of nature are about to turn ugly.

JERRAM: If we had an eruption

where these multiple craters evacuated,

it would be devastating.

It would essentially flatten this area.

NARRATOR: The eruption could be almost ten times more powerful

than the one at Santorini that shattered the Minoan world.

(music)

Vast amounts of volcanic material

would be ejected into the atmosphere,

blocking out the sunlight.

Global temperatures would plummet

with devastating consequences.

New scanning technology reveals remarkable evidence

lying hidden beneath the waters of the Mediterranean.

The raw forces of nature

still shaping this volcanic landscape.

Priceless evidence of the trade that drove the ancient world,

and an epic battle that changed the course of history.