All language subtitles for m.f.a.s02e05.1080p.web.h264-cbfm_track3_[eng]

NARRATOR: Ocean waves
hide a mysterious monument.

- This is huge.
Who or what could have created it?

NARRATOR: Satellite images
uncover a shocking find

on an isolated Arctic island.

- This is absolutely astonishing.

NARRATOR: Drone footage
shows a pair of huge craters.

- What happened here?

NARRATOR: And state-of-the-art
technology reveals

an unsettling subterranean mystery.

- Is this a ticking time bomb?

NARRATOR:
Everywhere we look on our planet,

there's evidence of the past.

In nature...

in buildings...

..in relics. Each holds a mystery

that technology now allows us
to see from above.

What new secrets are revealed?

- (monitor bleeping)

- (light music)

NARRATOR:
The world is full of strange

and seemingly inexplicable places
and phenomena...

..puzzling humans for centuries

and giving rise
to epic myths and legends.

But looking down from above,

the secrets behind
these ancient stories are revealed.

At the far southwestern tip
of Japan,

around 2,000 kilometres
south of Tokyo...

..lies a chain of islands
that make up

the most remote part of the country.

And the waters around
the westernmost island, Yonaguni,

hide a massive secret.

- The ocean here
is full of coral reefs

hosting amazing marine wildlife,
like dolphins,

sea turtles, and sharks.

NARRATOR:
But a view from above hints that

there's more than just sea life
below the waves.

- I can see there's a large shape
just under the surface,

but it's impossible to tell
what it is.

NARRATOR: To discover the secret
hidden in these dark waters,

we have to investigate
the mystery from above...

..from below.

- It looks like these steps
descending into the ocean.

- With all of these sharp edges
and right angles,

I mean, it looks almost structural.

- It looks like an underwater city.
What is this place?

- It really reminds me of legends
and myths such as Atlantis.

NARRATOR: Atlantis has captured
the imagination for centuries,

a story about
an ancient civilization

cast into the sea by angry gods.

BELLINGER: Atlantis is like
many other legends of lost utopias:

El Dorado, Camelot, Shangri-La.

I think these stories live on
because we want to believe

that there's more to discover
out there in the world.

- This raises
some really big questions.

- What on earth is this thing?
How did it get here?

- What is it made of?

AGRAWAL: I think
the most crucial question is,

is this manmade,
or is it a natural phenomenon?

WALTERS: It looks like
it's been made by modern machinery,

but if it's quite modern,
then why has it been flooded?

NARRATOR: What human-made object
could be this vast

and submerged
below the ocean surface?

Can a catastrophe
over 2,000 kilometres away,

on the northeast coast of Japan,
offer a clue?

WALTERS: Back in March 2011,
this part of the world

faced a once-in-a-lifetime disaster.

It was known as
the Great East Japan earthquake.

RISKIN: This was the most powerful
quake ever recorded in Japan,

but what made it infamous
was the tsunami it created.

GUY: Massive waves,
some recorded at a whopping

39 metres high,
smashed the coastline.

NARRATOR: This disaster sparks
an immense building project

to face the increasingly
destructive powers of the ocean.

- Before the 2011 disaster,
Japan already had

a considerable network of seawalls.

Now, seawalls are massive
concrete structures

which are designed
to protect inhabited coastal areas

from large waves that can come in
from typhoons and tsunamis.

- But even the world's biggest
seawall at the time, in Kamaishi,

which was two kilometres long,
was overwhelmed by the 2011 tsunami.

- After the disaster,
the Japanese government was

absolutely determined
to build back better.

AGRAWAL: This project is gargantuan,
covering hundreds of kilometres,

and it reaches 15.5 metres
at its highest points.

It's estimated to have cost
over $12 billion US.

NARRATOR: Could the strange
formation on Yonaguni

be a part of this major
seawall construction project,

or an older seawall
overcome by a tsunami?

RISKIN:
The island does have seawalls,

but they're all near inhabited areas
or infrastructure

like coastal roads or the airstrip.

The view from above shows that
this part of the coastline

doesn't really have
anything to protect.

NARRATOR: if it's not part of
a modern engineering project,

could it be something more ancient?

AGRAWAL: When you look closer
underneath the water,

that's when you really begin
to sense the scale

and the shape
of this massive object,

and start noticing these details
that look architectural.

BELLINGER:
To me, it kind of resembles ruins

of huge ancient structures
called ziggurats.

NARRATOR:
Over 7,500 kilometres away,

in a region known as Mesopotamia...

..could Bronze Age ruins
hint at the cause?

BELLINGER: Ziggurats are
distinctive stepped structures

developed in Mesopotamia
thousands of years ago.

They're believed to be
primarily religious

and may even have inspired the Tower
of Babel story in the Bible.

AGRAWAL: We're not
exactly sure how tall they were,

but what we can see today
are the remains of

much taller structures
that have eroded.

But one of them,
the Chogha Zanbil in Iran,

is still 24 metres high.

RISKIN: And they're still
incredibly imposing.

It's amazing to think
these structures

have survived for so long.

NARRATOR: Could the strange
underwater formation

on the shores of Yonaguni
be a similar ancient edifice?

BELLINGER: There certainly are
marked similarities

between the structures.

The underwater site
has step-like features

leading up from the base,
just like a ziggurat,

and it's 25 metres high,
around the same

as the ruins of the Chogha Zanbil.

- Now, the base is much bigger
than any Mesopotamian ziggurat.

So, if that's just
the foundation of a building,

you can start to imagine
how tall it would be.

- Could it be a similar type
of religious structure?

NARRATOR:
Or could this be the remains

of something more substantial?

An ancient city
swallowed by the ocean?

BELLINGER: We're used to thinking
about cities lost under the sea

in terms of myth,
like the city of Atlantis,

but it has actually happened
more than once

and sometimes,
catastrophically fast.

NARRATOR: Almost 15,000 kilometres
away, in Port Royal, Jamaica,

a sudden disaster
claimed a thriving city.

- Port Royal was known
as the wickedest city on Earth.

And that was for good reason
because it was a haven for piracy

and a major slave-trading hub.

Now, what on earth is gonna take out
such a wealthy and thriving city?

RISKIN: The secret
is actually hiding under the city.

Instead of being built on bedrock,
it was just sand,

which turned out to be
the city's Achilles heel.

WALTERS: When a massive earthquake
began shaking the island in 1692,

it all started to fall apart.

NARRATOR: But how could
the disaster sink the city?

RISKIN: The tremors likely caused
something called liquefaction.

That's a process that turns
the seemingly solid ground

into something more like quicksand.

That, combined with a huge
tidal wave from the quake,

caused an unbelievable
two-thirds of the city to sink.

NARRATOR:
So, could the massive feature

under the coastal waters
of Yonaguni...

..be part of a lost city
hidden by natural forces?

RISKIN: It's an interesting theory.
One Japanese marine geologist,

Masaaki Kimura, who has
studied the site for years is

convinced that there are signs that
this is part of a long lost legend.

- He has found what he believes are
clear signs that this is manmade.

GUY: There are shapes that
he thinks look like tool marks,

and even writing
in some of the rocks.

- There are areas that look like
stairs, gutters, and even doorways.

BELLINGER: And there are
two features he believes are art:

a carving of a turtle, and a face.

NARRATOR: Are these marks and shapes

evidence of human hands at work
thousands of years ago?

BELLINGER: Kimura connects this site
to an ancient civilization

on the legendary
Lost Continent of Mu.

NARRATOR:
Do these clues reveal the secrets

of a forgotten eighth continent
hidden beneath the Pacific Ocean?

- The concept of Mu first
came about in the late 19th century,

and it was a reiteration
of sorts of the Atlantis myth.

NARRATOR: In the 1920s,
an occultist expanded the story,

describing a 50,000-year-old
civilization of 64 million people,

thriving on a continent
bigger than South America

in the middle of the Pacific.

- Now, he claimed that Mu
was this kind of Ur civilization,

the origin of all those great
historic civilizations that we know

in places like Egypt,
Greece, Central America.

-The legend says that the continent
disappeared in a single day

due to a combination of volcanoes

and granite bedrock riddled with
caves and full of explosive gases.

- Could anything possibly have made
a massive continent vanish?

The short answer to that is no.

GUY: The problem is it's just not
scientifically plausible.

A continent that big can't just
disappear in a moment, even if

it's full of caves and holes,
as some of the myths highlight.

- Frankly, it's complete BLEEP.

And that's not the only flaw
with Mu.

BELLINGER: As the story goes,
the Mu civilization

was dominated by
a self-styled superior white race,

and its modern Pacific descendants
denigrated as uncivilized cannibals.

Unfortunately,
typifying the racist pseudoscience

popular in the 19th
and early 20th century.

WALTERS: Scientific racism
has always been historically used

as a kind of way
of justifying social inequality.

What it does is it makes it seem
like all those status differences

are a product of "nature".

Now, that is complete nonsense.

It's seriously nasty, actually,

and it's really
very harmful as well.

NARRATOR:
So, what else could explain

the massive formation at Yonaguni?

Is it possible that humans
weren't involved at all?

- Could this be an entirely natural
geological formation?

NARRATOR: All over the world,
we find incredibly perfect

rock formations
made entirely by nature.

- The rock here on Yonaguni
is mudstone and sandstone,

which can create
dramatic geometric formations too,

like the ones in Utah or Arizona.

- If you look around the island,
there are some notable

natural landmarks that look quite
similar to some of the shapes

that we see on the monument.

- In these formations,
you can see the same kind of

angular shapes
that we see underwater.

There's even a rock
that looks like a face.

- But does that necessarily mean
that this awe-inspiring

natural monument has never been
shaped by human hands?

NARRATOR: Might ancient humans
have built upon

this natural formation
when it was above the water?

- You have to go back something
like 10,000 years to find a time

when this would've been
above the surface of the ocean.

So, were there
humans on the island back then?

BELLINGER:
It's impossible to say for sure.

There are signs of
human habitation on nearby Taiwan

around 20,000 to 30,000 years ago,

so perhaps part of this rock
might have been accessible too.

RISKIN: And evidence shows that
this has been underwater

for thousands of years.

That is plenty of time
for ocean currents

to smooth away the fine details.

GUY: And if there's one thing
we know about humans,

we love to leave our mark.

NARRATOR: From ancient legends,
to dramatic geological wonders,

to prehistoric humans,
theories abound.

There is no way to know
for certain the true cause

of this underwater monument.

And, for now,
the ruins remain a mystery.

AGRAWAL:
I'm quite confused actually.

I can't really tell if it's
a natural or human-made structure.

WALTER: To me it looks manmade.
It's got lots of straight lines,

it looks kind of geometric,
it looks deliberate.

RISKIN: I think the most plausible
explanation is that

this is a natural formation.

GUY:
For me, what's most interesting is

everything that we are learning
in search of that answer.

- Either way, it's a fascinating
and impressive sight,

and one that is really uncovered
by looking down from above.

NARRATOR: From tropical waters
to the freezing Arctic Ocean,

the view from above reveals
strange sights that inspire

timeless legends
and hide shocking histories.

Over 6,000 kilometres
north of Yonaguni,

just off the coast of Siberia,

lies the craggy,
deserted island of Kolyuchin.

- This is a very rocky island with
high cliffs,

and it's in the Arctic,
so we know right away

that it must be pretty inhospitable
for most humans.

NARRATOR: There shouldn't be
anything out here,

but high-resolution satellite images
reveal something unexpected

on the northern tip of the island.

WALTERS: What I can see
are these kind of greyish,

boxy shapes that stand out from
the green of the surrounding land.

NARRATOR: Drone footage reveals
a closer look at the stunning site.

- They are some kind of houses,
but they look run down and damaged.

- Clearly,
this is some kind of abandoned site.

NARRATOR: And among the ruins,
an even more shocking scene.

- Polar bears!

It looks like an abandoned town,
but polar bears are all over.

GUY: There's around 30 of them,
which is pretty astonishing.

They're standing in
these dilapidated buildings,

poking their heads out of windows,
doing things that I wouldn't

really expect
polar bears to be doing.

- You know, it just looks wrong.

BELLINGER: The mythology
of many Arctic peoples is rich

with stories of polar bears
as powerful, human-like creatures

who could act as friend or foe.

- But could legends actually explain
what they're doing here?

NARRATOR: Two mysteries
are entwined on Kolyuchin:

why are the polar bears here,

and what are these strange
abandoned buildings?

- Why would anyone build
these structures

on this really isolated island?

I mean, what on earth are they for?

- Could any events
from the island's past shed light

on why these buildings are here?

NARRATOR: Archival footage from
the early 1930s reveals

a harrowing event in the seas nearby
that may hold a clue.

RISKIN: You can clearly see
that this massive ship

is stuck in the ice, but why was it
even here in the first place?

Why would anyone sail
in these dangerous waters?

WALTERS:
This is the S.S. Chelyuskin,

a Soviet ship, which was on
an expedition to see if a ship

that wasn't an icebreaker
could make it through something

called the Northern Sea Route.

RISKIN: The Northern Sea Route
is of major interest today

because of how it could
significantly reduce the time

and the cost
of some shipping routes.

And that possibility was just
as attractive back in the 1930s.

NARRATOR: The voyage
starts August 2nd of 1933,

with a film crew aboard
to document their bold mission.

And after weeks at sea,
it seemed destined for success.

- The S.S. Chelyuskin
was just a few miles

from open water
when disaster strikes.

- They get caught in the ice.

BELLINGER: For months
they drift farther and farther north

as winter approaches
and the days get shorter and darker.

GUY: They're regularly radioing
the mainland to ask for help,

but it gets even worse.

WALTERS:
It's February the 13th, 1934,

and that ice pressure
finally overpowers the ship's hull.

And as a result,
the ship begins to sink

and one crew member is killed.

- Luckily,
they'd planned for the worst

and managed to abandon the ship.

But then how do they survive?

RISKIN: This is the Arctic
in the middle of winter.

So, it's incredibly cold, it's dark,

and the weather can change
in a moment.

You can get blizzards,
you can get fog, you can get storms

that spring up out of nowhere.

That all makes any rescue attempt
difficult and dangerous.

So, how is it even possible?

NARRATOR:
A daring air mission begins

to attempt to rescue the survivors.

- The stranded survivors built
a makeshift airstrip on the ice

so that the planes can land.

RISKIN: But these planes
are so small, it takes several

of these dangerous trips
to rescue everyone.

- What's astonishing is that
they actually make it.

I mean, these people had survived
out on the ice for months,

and they make it home safely.

NARRATOR: But what can
this incredible rescue

reveal about the strange buildings
on Kolyuchin Island?

RISKIN: Could the buildings on the
island somehow be connected to

the original mission
of the Chelyuskin

sailing the Northern Sea Route?

WALTERS: The secret lies in

the 20th-century ambitions
of the Soviet Union.

The potential for the Northern
Sea Route is phenomenal.

But as
the S.S. Chelyuskin discovered,

to succeed you need
up-to-date information

about all the local conditions.

That is absolutely crucial
for success.

RISKIN: The ocean and the weather
along the Northern Sea Route

are really intense and dangerous,
and they can change really fast.

YATES-ORR: The Soviets had to figure
out how to manage the danger

of this unpredictable region.
So, what did they do?

WALTERS: The Soviet Union started
to build this whole network

of polar stations all the way along
their northern coastline.

And in 1943,
one was built on Kolyuchin.

RISKIN: But with climate change
making the Northern Sea Route

more accessible than ever,
Russia still needs these stations,

so why was this one abandoned?

WALTERS: The late 1980s and
the early 1990s were a time of huge,

vast upheaval for the Soviet Union,

and ultimately led to its collapse
at the end of 1991.

RISKIN: The new Russian government
just didn't have the cash to keep

funding this scientific outpost,
so it closed in 1992.

YATES-ORR: So, the people move out
because the money is gone,

but when do the polar bears move in?

And why?

NARRATOR: Could the myths
and legends of the arctic peoples

reveal the secrets of this uncanny
polar bear behaviour?

WALTERS: The Chukchi people
have been living in Siberia

for hundreds, actually,
perhaps thousands of years,

and they've mastered how to survive
in this fantastically harsh climate.

Even today, many are still relying
on the traditional ways

of herding reindeer
and hunting sea mammals to survive.

NARRATOR: With their long history
in the Arctic, polar bears have

long been a familiar sight
to the Chukchi people.

- And the Chukchi legends are
full of stories about polar bears

who think, talk,
and act much like humans.

They say polar bears
are so human-like that

they live in villages,
and even have their own country

far out on ice floes
in the open seas.

NARRATOR:
And just 420 kilometres away,

a nearby island offers a clue
to the source of these legends.

BELLINGER: This real-world island
may have inspired

the legend of
the polar bear country.

- This is Wrangel Island,
a UNESCO World Heritage site,

and the most biodiverse region
in the High Arctic.

- Wrangel Island is an absolute
haven for polar bears.

More polar bears give birth here
than anywhere else.

GUY: It really makes you wonder,
I mean, what's so special

about this island, and why are there
so many polar bears here?

- Location, location, location.

As the weather begins to warm
in the spring,

sea ice retreats northward.

Polar bears need somewhere to stay
until the thick ice cover returns.

NARRATOR: But this idyllic haven
may be turning into a trap.

RISKIN:
Climate change has been messing with

the polar bear's schedule.
The ice melts earlier in the year

and it freezes later,
meaning the polar bears

are stuck on land
for longer periods.

GUY: So, this is a big problem
because polar bears

mainly hunt on the ice.

- On land,
they're basically fasting.

NARRATOR: Could climate change
be connected to the appearance

of the polar bears
on Kolyuchin Island?

GUY: It's rare that polar bears
appear on Kolyuchin

in such large numbers,
and a few elements

have to combine to make this happen.

RISKIN: No one knows exactly why,
but every few years,

the floating ice on the sea remains
near the shore in the summer months.

And that means the bears
don't travel

as far north to follow the ice.

GUY: When this footage was taken,
there were fewer bears than normal

on Wrangel Island,
indicating that the ice was keeping

these bears further south,
like in Kolyuchin.

- But why are they poking around
these old buildings?

RISKIN: Polar bears are
extremely curious animals.

It's actually not that unusual
for them to poke around

and try to get into doors
and windows.

NARRATOR: With global warming
continuing to drastically affect

the Arctic, we can only wonder
what other changes are in store.

GUY: I can't be sure what will
happen next for the polar bears,

but climate change is likely
to continue to present them

and the rest of this ecosystem with
a lot of challenges moving forward.

But whatever happens,
I'm sure that these amazing

and intelligent animals
will continue to surprise us.

NARRATOR: From
the hidden secrets of the Arctic

to ancient, jagged mountains,
myths seek to explain

the astonishing and unexpected,

but a search from above
could uncover the truth.

Over 8,000 kilometres
to the southwest,

in the warm waters
of the mediterranean,

lies the home of one of the most
famous pantheons in history:

Greece.

BELLINGER: When you look at
the dramatic landscape

of the country,
it's no wonder the ancient Greeks

told so many stories
about gods in connection with

strange features in the landscape.

NARRATOR: Legends like
Mount Olympus, home of the gods,

the sacred Psychro Cave
where Zeus was born,

and the Pholoe Forest where centaurs
and dryads roamed.

And in the quiet, arid mountain
brush of the Argolis region

does the bird's-eye view
reveal one more?

YATES-ORR:
There are two massive craters

smashed into the side
of this mountain!

GUY: It looks like a giant
almost took their fists

and slammed them into the earth.

RISKIN: These are really big.

Both of them
are over 200 metres across.

- The land around looks
quite arid with some green brush,

but inside, you see this
much richer, brighter plant life.

- What are these things?
BELLINGER: What made them?

Was it some sort of natural
geological process,

or is it a sign of some kind of
human activity?

- Did these just suddenly appear, or
have they been around a long time?

- And there are already two of them,
are more going to appear?

NARRATOR: What clues can be found
looking down from above?

- What could create round holes
like this, and in pairs?

- Is there anywhere else
we can see this sort of formation?

NARRATOR:
About 190 kilometres to the north,

another pair of round features
in the landscape raise questions.

- These holes are a similar size
to the ones on the mountain.

RISKIN:
But these holes are full of water.

It's pretty unusual to see
an almost perfectly round lake,

but to see two of them
side by side is really weird.

NARRATOR: What could
have created these strange features?

GUY: For a long time it was thought
that these might be

volcanic in origin,
but a study in 2010

found something unexpected
in the lake bed.

RISKIN: There was molten zirconium
at the bottom of the lake,

and that's wild because
the melting temperature of zirconium

is over 1,800 degrees Celsius.

It's insanely hot.

GUY: So, you think something that
hot must be from a volcano,

but lava only gets up to
a temperature of about

1,200 degrees Celsius.

So, where did all that
extra heat come from?

NARRATOR: To make something that hot
and cause a hole that big,

you're looking at powers
from out of this world.

GUY: The researchers believe that
the lakes were caused

by a meteorite that smashed into
this area at least 7,000 years ago.

NARRATOR: Could these two
rocky holes in Argolis

be the result of a space rock
crashing into the mountainside?

GUY:
So, it's one possible explanation,

but confirmed impact craters
are quite rare.

In fact,
there's only around 40 in Europe.

- And we just don't know if
there are telltale geological signs

of meteorite impact
at this site in Argolis.

- So, ultimately, a meteorite
impact is pretty unlikely.

So, are there any other
possible explanations?

What else could be going on here?

NARRATOR: Perhaps a more
modern disaster could hold a clue.

Around 11,000 kilometres away,

Guatemala city residents
hear something alarming.

- It was 2010, locals reported
that they could hear the crash

or the thud of materials
underground.

NARRATOR: And on May 30th, 2010,

a massive hole
suddenly opens in the ground.

RISKIN: The satellite view
and aerial footage from helicopters

show paved roads plummeting
into this huge pit in the ground.

YATES-ORR: What could've caused
this kind of damage

in the middle of a modern city?

GUY: A lot was happening around
Guatemala City in May of 2010.

First, we've got the eruption
of the Pacaya volcano on the 27th,

and many of the tremors
destabilized the ground.

YATES-ORR: Then Tropical Storm
Agatha dumped rain on the city,

causing landslides
and flooding the streets.

The water and ash filled the city's
drain pipes with water and debris.

BELLINGER: And this overwhelmed
the poorly maintained system.

It's a recipe for disaster.

RISKIN: Some pipes burst,
and suddenly you've got

a tsunami's worth of water
surging into the ground.

NARRATOR:
But how did some leaky pipes

cause a cavernous hole
in the middle of the street?

- Guatemala City is built on top of
layers and layers of volcanic ash.

BECHTEL: The volcanic ash contains
some very, very fine particles

that makes it unstable
when you introduce water.

GUY: So, during a big storm
or with a burst pipe,

that process of erosion
suddenly gets a lot more intense.

BECHTEL: That movement of water down
through the volcanic ash carries

the very fine particles with it,
and that creates a void.

This gets closer
and closer to the surface.

Eventually, the roof
is thin enough that it can't support

the weight of whatever's up there,
so it falls in,

and it leaves this
terrifying-looking wormhole.

NARRATOR: So could these two holes
in this Greek mountainside

be the result of the same
dramatic process?

RISKIN: There are really important
elements missing.

First of all,
this area is really arid.

Argolis is actually
one of the driest places in Greece.

GUY: You can see by
looking down from above,

this is nothing like
a major city, right?

There definitely aren't any leaky
pipes seeping water into the ground.

BECHTEL: And the terrain in Greece
is not at all

geologically like the terrain
in Guatemala City.

This is not volcanic ash.
This is true karst.

RISKIN: Karst is a type of land
made up of rocks like limestone

that can dissolve in water,

and because of that, they tend to be
full of networks of caves.

BECHTEL: I was immediately
reminded of the cenotes

in the Yucatan Peninsula
in Central America.

NARRATOR: The Yucatan is around
10,600 kilometres away, in Mexico.

BELLINGER: The ancient Maya
believed the cenotes

were a gateway to the underworld,

and made offerings to the gods
they believed to dwell there.

GUY: The Yucatan cenotes were likely
formed about 150,000 years ago

during the last interglacial period.

They continued to be shaped
as the glaciers grew

and sea levels dropped
heading into the last ice age.

BECHTEL:
Over thousands to millions of years,

rainwater that falls infiltrates
into the rock, and as it flows,

it dissolves the rock
and creates openings.

RISKIN: And in some places,
the roof collapses,

creating these cenotes or sinkholes.

GUY: When the last ice age ended
and sea levels rose,

the caves once again
filled with water.

NARRATOR: Are the craters in Argolis

cenotes on the other side
of the world?

RISKIN: Cenotes can form anywhere
if the terrain is right,

but these craters
are missing fresh water.

GUY: So, does this mean that
there was never enough water here

to make a sinkhole
in the limestone terrain?

NARRATOR: There may be a clue
in ancient Greek myths.

BELLINGER: Just like the ancient
Maya, Greek mythology is rich

with stories of underground rivers
tied to the land of the dead:

the underworld.

- There are so many stories that are
consistent with karst features.

Like the River Styx in karst,
there really are underground rivers.

YATE-ORR: Now, this hints at
a real-world historic knowledge

of flowing water under the surface,

which would've made caves
in the limestone here.

BECHTEL: Because of
the arid conditions in Greece,

there's not enough water for
significant dissolution

to be happening, so these features
happened in the distant past

when it was a much wetter climate.

GUY: These craters may have looked
just like the cenotes

in the Yucatan, but when?
And where did all the water go?

NARRATOR:
When in history was this arid region

wet enough to create
these caves and sinkholes?

BECHTEL: Earth's climate has changed
dramatically in the past,

thousands to millions of years.

The network of solution cavities
that allowed these craters to form

were mostly dissolved at a period
when climate was a lot wetter.

YATES-ORR: If we look deep
into the geologic past,

about 7 to 11 million years ago,

this part of the world was humid
and experienced heavy rains.

RISKIN: So, it makes sense
to think that these two craters

are cave-collapse sinkholes that
were formed millions of years ago.

NARRATOR:
And there's one more mystery.

- How these craters may have formed
is one part of the story,

but I'm really interested in what's
happening

inside these craters, right?

That vegetation seems to be so much
more lush than the surrounding area.

BECHTEL: Crater walls tend
to produce ecological isolation

so that ecosystems
develop inside these.

The crater itself has produced
a little microclimate.

NARRATOR: And that provides
the conditions for these trees

and grasses to flourish
in this otherwise arid land.

- We can't be 100% sure
what caused these craters

without further investigation
on the ground,

but the view from above
has uncovered strong theories

about the ancient past of this site.

GUY: These craters are relics
of a time when our world

looked vastly different
than it does today.

- And it reminds us
of the powerful geologic forces

that are enshrined in ancient myth.

NARRATOR: From mountain peaks
to fiery powers

lurking beneath
the earth's surface...

..when these legendary forces
break free, they shape the world,

and inspire foundational myths.

Almost 10,000 kilometres away,

amid the mountains
of the American West,

lies a world-famous site.

GUY: Yellowstone National Park
is one of America's treasures,

known for the wildlife
that live there,

but also the amazing landscape.

YATES-ORR: There are thousands of
unique and beautiful sites

around the park
that look very different

from the usual forest and fields
of the Midwest.

BELLINGER: These unique
and enduring features made the area

a holy site
for many Native American peoples.

The Apsaalooke people,
through their traditions,

consider this area
a very important spiritual place

which sustains them
throughout their lives.

And Kiowa legend says their creator
gave them this area as homeland,

earned when an ancient hero
bravely dove into a boiling lake.

NARRATOR: But what is behind
this legendary landscape?

And what can it tell us
about the future of this wilderness?

In late 2022, new technology
examined the site from above

and revealed hidden secrets
plunging deep into the earth.

- We have the technology
these days to basically take

an x-ray of the Earth.

GUY: So, a supercomputer
analysed the latest seismic data

around Yellowstone,
and created this 3D picture

of exactly what is hiding
underneath the surface.

YATES-ORR: And what researchers
discovered was almost unbelievable.

As we're looking at the land,
there's something that lies beneath;

kind of a core.

KOUROUNIS: Think of this
as a cross-sectional

side view of Yellowstone.

At the top, we've got the surface
where all of the trees

and parking lots,
and Old Faithful is,

but then as you go deeper down,
we can see these vast chambers.

- It appears that there's this
massive hole filled with something.

RISKIN: It's in different
chambers at different depths,

and all of it is very dynamic
and moving.

NARRATOR: And this subterranean
phenomenon is unbelievably vast,

stretching 72 kilometres across
and over 150 kilometres down.

- I wanna know what we're looking at
and if it's potentially dangerous.

KOUROUNIS:
How long has this been here?

And is it changing?

NARRATOR: What is going on
beneath Yellowstone Park?

There may be a clue best seen
from several kilometres straight up.

- It can only truly be seen
when you look down from a satellite.

GUY: There's this massive
depression in the earth.

It almost looks like the ground
between the mountains

is sinking back down.

NARRATOR:
What could create this vast imprint,

covering an area of
70 by 45 kilometres?

- It's an absolutely
enormous volcanic caldera.

- But what kind of volcano
could make a caldera that huge?

And where is it?
I mean, this area is flat.

- Yellowstone is actually
something called a supervolcano.

And the only thing scarier
than a volcano is a supervolcano.

NARRATOR: These are far larger
than regular volcanoes.

Mount St Helens, source of
the deadliest eruption

in US history,
is dwarfed by Yellowstone.

The caldera is over 20 times as big.

- In a regular volcano,
magma spews out from a vent

in the Earth's crust,
and then it solidifies,

and it builds up volcanic shape like
a cone or a dome on the surface.

But in a supervolcano, the magma
can't push up through the crust,

so the pressure
just builds and builds,

and it forms this huge bulge
in the surface.

Then, cracks form
and gas and ash leak out

until finally, the whole thing just
bursts with one massive blow.

Once the magma has escaped,
the chamber collapses inwards,

and it leaves this massive caldera.

- That means that the huge area
of molten rock under Yellowstone

must be volcanic magma.

KOUROUNIS: This partially liquid,
half-melted rock is sitting there

just building pressure slowly over
thousands and thousands of years

- It's rather unsettling to picture
a massive lake

of boiling rock under your feet.

- And its base
extends even farther down.

The Yellowstone plume
is thought to be

something called a 'mantle plume'.

That means the root of this plume
is something like

3,000 kilometres down in the earth.

- And those weird features
on the surface,

steam seeping out of the earth,
boiling lakes, geysers,

they're all signs of the heat
and pressure hiding below.

NARRATOR: And the 3D image reveals
something even more shocking.

- We're actually closer
to the conditions

of an eruption than we ever thought.

GUY: The new images reveal that
the magma is only about

three miles deep, higher than
the experts previously thought.

RISKIN: And the melt, that's
the fluidity of the magma,

is higher than we knew.

GUY: Magma is a mixture, right?

You've got this liquid rock,
but also dissolved gases,

crystallized minerals,
and larger chunks of rock.

So, the melt percentage is just how
much of that mixture is molten rock.

- And here, it's around 16-20%.

GUY: That's unnerving,
because as far as we know,

the melt percentage only needs
to be around 35 to 50% to explode.

- Is this supervolcano
a ticking time bomb?

NARRATOR: With every supervolcano,
it's not a question of if but when.

- It makes you wonder when and how
it'll finally reach the surface.

NARRATOR: A clue might lie
around 5,000 kilometres away,

in the middle of the Pacific Ocean:
the island of Hawaii.

This is Mauna Loa, one of the most
active volcanoes in the world.

BELLINGER: Hawaiian myth says Pele,
goddess of volcanoes and fire,

created the whole chain of islands

and is behind the eruptions
even today.

NARRATOR: But what forces
power this mythic goddess?

- Mauna Loa is over a hotspot,
just like Yellowstone is,

and the ongoing eruptions there
over millions of years

have formed the Hawaiian Islands.

- But what can these eruptions
tell us about Yellowstone?

NARRATOR:
The clue lies in the lava itself.

GUY: Hawaiian eruptions
like the one from Mauna Loa

aren't these massive explosions
but rather these slower,

ongoing flows
known as effusive eruptions.

- This really fluid lava
is made largely of basalt,

and when it cools, it can leave very
specific types of land formations.

YATES-ORR: So, the question is
are there any signs

at Yellowstone like this?

RISKIN: There is one famous
and ancient site

in Yellowstone National Park
that connects

to this Hawaiian-style
basalt lava flow.

NARRATOR: Obsidian cliff.

GUY: The appearance and composition
of the Obsidian Cliff tells us

that it was created by this thick
lava flow that cooled very quickly,

similar to what we see at Mauna Loa.

YATES-ORR: So, that means
we could see another flow like this,

but Yellowstone is capable
of something much, much bigger.

NARRATOR: What explosive
superpower could burst

from below
Yellowstone National Park?

And what devastation
will it unleash?

- How can we figure out
what will happen next?

NARRATOR: A clue may lie around
14,000 kilometres away in Indonesia.

The idyllic waters of Lake Toba hide
the caldera of another supervolcano.

GUY: It's a massive lake,
100 by 30 kilometres,

and just over 500 metres deep.

- Toba is another supervolcano that
erupted around 74,000 years ago.

KOUROUNIS: And the reason it left
such a big mark on the landscape?

The Toba event was gigantic.

It's the biggest known eruption
of the past 2.5 million years.

- So, what was the impact
of this massive explosion,

and what clues can it give to what
might happen at Yellowstone?

RISKIN: When Toba erupted,
it unleashed a tonne

of destructive power.
First, there was the lava flow,

at least 2,500 cubic kilometres
of dense pyroclastic material.

That volume is so big,
it's hard to imagine.

It's almost twice as big
as all the water in Lake Ontario.

- It also had a massive
ash cloud that spread westward

across the Indian Ocean
and reached Africa.

- And the blast probably caused
tsunamis reaching India,

Africa, and even Australia.

NARRATOR: Could an eruption of this
magnitude happen at Yellowstone?

- To find the answer,
we need to look down from above.

RISKIN:
Yellowstone caldera is a remnant

of one of these major eruptions.

But astonishingly, there are
two more gigantic calderas.

GUY: That means
there have been three major

supervolcano-level eruptions here.

But when? And how big were they?

YATES-ORR: The oldest and biggest
caldera is the result of the largest

of Yellowstone's
big three eruptions.

RISKIN: This one happened a little
more than two million years ago,

and it released a whopping
2,500 cubic kilometres of material.

That had ash fall at least
as far as California,

probably all over the world.

BELLINGER: But this was a time
when no humans were at risk.

Now, there are over
300 million people in the US.

NARRATOR: So, what would it mean if
something like that happened today?

GUY: The potential magnitude
of an eruption from

the Yellowstone supervolcano
is mind-blowing.

KOUROUNIS: Because of
the massive pyroclastic flows,

about a 100-kilometre radius around
the volcano would be a kill zone.

RISKIN: And some computer models
predict that depending on

the duration of the eruption,
you would be looking at ash fall

across the whole of
the United States.

- With that much ash, an impact on
the global climate is also possible.

- This would really be
a world-altering event.

NARRATOR: With so much at stake,
can modern science help us predict

when Yellowstone will blow?

RISKIN: There's actually some really
cutting-edge technology

that's improving our ability
to predict volcanic eruptions.

NARRATOR: Around 3,800
kilometres away, in Guatemala,

one project takes place
above the active Volcan de Fuego.

GUY: The best place
to measure data from a volcano

is near an active vent...
but that also happens to be

the most dangerous place you can be.

KOUROUNIS: With a place
as active as Volcan De Fuego,

you'd be risking your life
to get near the top.

- The solution?
Specially designed drones.

These amazing machines
can climb over three kilometres up

and then fly right into
the ash clouds above the volcano

to collect measurements and samples.

GUY: It's amazing.
These drones are going places

that humans never could,

and they're collecting data
from above to solve

the mysteries of volcanic eruptions.

NARRATOR: Ancient civilizations
created fascinating myths

and legends to explain the potent
volcanic powers of the earth,

powers we're still seeking
to fully understand even today.

KOUROUNIS: What I find
fascinating is how little

we really know about it,
despite the fact that it's

one of the most closely monitored
volcanoes on planet Earth.

GUY: For now, we'll just have to
keep our eye on

these "Mysteries From Above".

BELLINGER: Given the grandeur of
so many natural features

in our world, it's no wonder
people resort to tales of gods

or sorcery to explain what they see.

NARRATOR: With cutting-edge
technology and a view from above,

we can pursue
the answers to these mysteries.

Subtitles by Sky Access Services