All language subtitles for Mysteries.from.Above.S03E06.1080p.WEB.h264-BAWD_track3_[eng]

NARRATOR: Drone footage reveals
remnants from the past.

- What is this place?
And why's it underwater?

NARRATOR: An aerial view uncovers
a puzzling pattern

and an eerie mystery.

- Who was John Greer?

And why is his tombstone
in the middle of the Gulf of Mexico?

NARRATOR: Eyes above the ocean floor
capture an incredible sight.

- If it is a road how old is it?

NARRATOR: Satellite images shed
light on an ancient mystery.

DAN: The belief is that
these formations could be as old

as 40,000 years!

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?

Water. It covers more than 70%
of the Earth's surface.

And yet we know more
about the far reaches of space

than we do
about the depths of our own oceans.

But the view from above
is beginning to lift the veil

on these hidden places
and revealing new mysteries.

Just off the coast of Italy,
in the Gulf of Naples,

a view above the blue waters
reveals something incredible.

Could a closer look yield clues?

Just below the water's surface
a clearer picture begins to emerge.

CYLITA: Divers have found
rich marble floors

and mosaic tiled pools

hidden for centuries under the sand.

GUY: Now, what's incredible is
that this site covers

an area of more than 170 hectares.

NARRATOR: A massive expanse
of submerged ruins

and something even more haunting,

scores of sunken statues.

- What is this place?
And why's it underwater?

NARRATOR: Can the view
from above provide answers?

Found along the neighbouring
shoreline are more ruins.

These are remnants of an ancient
Roman city known as Baiae.

DAN: But somewhere along the line,
half of this harbour city

got swallowed by the sea
and lost for centuries.

NARRATOR:
What led to this unfortunate fate?

And what else can be learned
with a view from above?

GUY: Now if you want to begin
to unravel the mystery of Baiae,

understanding its location is key.

Baiae is located
on the coast of Italy,

south of Rome, which, of course,

was one of the greatest capitals
of the ancient world.

SHEILA:
It was from this place that rulers,

politicians and businesspeople

controlled the Roman Republic
and later the Roman Empire -

one of history's largest powers.

NATASHA: And Baiae is
where these important players

would come in search of something
the Romans called "Otium."

SHEILA: "Otium" can be translated to
"a pause", "a break", or "leisure".

GUY: To put it simply,

this is where Rome's rich
and powerful went on holiday.

NARRATOR:
And it's where many of Rome's elite

built their vacation homes.

- You might recognise the names
of some of the property owners

including Julius Caesar,

politician Mark Antony, the
statesman and Philosopher Cicero,

as well as
the infamous Roman Emperor Nero.

GUY: Given the enormous amount

of wealth and power
concentrated here,

this seaside resort evolved
or, perhaps we should say,

devolved into a kind of Sin City.

NATASHA: The writer and philosopher
Seneca the Younger

once described Baiae
as a "vortex of luxury"

and "harbour of vice."

- The story of Baiae does have
parallels to the legend of Atlantis.

NARRATOR:
The Greek Philosopher Plato

famously wrote
about a great civilisation

that sank beneath the sea.

And while his tale of Atlantis
is understood to be a myth,

the similarities are uncanny.

SHEILA: Plato's moralistic tale
talks about this advanced society

that becomes morally bankrupt
with its people

devolving into immoral pursuits.

- And as Plato explains,

this behaviour angers the gods,
it does not go down well with them.

And so they send down punishment

in a "terrible night of fire
and earthquakes".

And a punishment
that caused Atlantis to sink forever

beneath the waves.

NARRATOR: What was it that seems
to have caused Baiae

to suffer a similar fate?

Once again, could the view from
above open a window to the past?

This is known as the Imperial Villa

and over the years was used
by several Roman emperors.

GUY: Perhaps it's because
of its place - high on a hill -

that this Imperial Villa is one of
the few that seems to have avoided

Baiae's unfortunate fate.

GEORGE: This place was built way
back in the 1st Century BCE.

And if you think home theatres
are impressive today,

this place included
a Greek-style theatre

that could host 1,400 or so
of your closest friends.

- The estate would have also
included magnificent water features

and marble statues,

not unlike the statues found
within the bay below.

NARRATOR: As researchers continue
to discover the scope and scale

of these impressive villas and
seaside mansions,

one question remains:
Why are they all under water?

What more can the view
from above teach us?

NATASHA: The area was renowned
for its natural beauty

and panoramic views of the coast,

but there was
another important draw.

NARRATOR: On the shores,
high over the sunken ruins -

and in a part of Baiae
that was spared disaster -

the view from above reveals
an important piece to this puzzle.

SHEILA: This massive concrete dome
is known as the Temple of Mercury.

It measures over 70 feet
in diameter.

And when it was built it was
the largest dome of its kind,

pre-dating the Pantheon in Rome.

GUY: For its time,
this design would have been

seriously state of the art.

SHEILA: But, while the Dome's
cutting-edge architecture

speaks to Baiae's importance,

for centuries its function
was misunderstood.

NATASHA: Early archaeologists
first identified it as a temple

dedicated to Mercury - the Roman
god of finance and commerce.

- And nearby they found
two other domes

that they called the Temple of Diana
and the Temple of Venus.

- Now, for years it was believed
that these domes

must have been important
Roman temples,

but that was wrong.

Eventually, it was discovered
that these buildings

were actually enclosures for pools.

DAN: These weren't temples at all,
they were Roman baths!

And they were part
of a much larger spa complex.

SHEILA: But why build it all here?

Because they were able to exploit
a particular local resource.

NATASHA:
That's because this entire area

is rich with geothermal hot springs.

The engineers that built these spas
managed to harness

the region's geology to provide
the hot water and steam they needed

for the spas' luxurious
baths and saunas.

GEORGE: But often
when you've got places like this,

full of hydrothermal activity,
there's a catch.

And that's volcanic activity.

DAN: And that is definitely
the case here.

In fact, this is one
of the most seismically active

places on the planet.

NARRATOR: In fact, Baiae is
surrounded by several volcanoes.

And one of them
is notoriously destructive.

About 30km
from the ancient spa town

sleeps the powerful and deadly
volcano of Mount Vesuvius.

GUY: In the year 79 -

when the people of Baiae
were likely to be partying hard -

you have Mount Vesuvius erupting
with little to no warning.

- And this violent volcanic eruption
buried several nearby cities

including Herculaneum,
Oplontis, Stabiae, and Pompeii.

Pompeii, of course, is
the most famous of these, in part,

because of those ghostly casts

that preserve the forms
of its many victims.

NARRATOR:
Could these haunting scenes

somehow relate to the underwater
spectacle found in Baiae?

An area of ruins three times
the size of those at Pompeii?

GEORGE: Despite its proximity
to Mount Vesuvius,

Baiae was luckily spared
from its destruction.

But there was another danger
lurking from beneath.

NARRATOR:
A danger hiding in plain sight

now visible with a view from above.

CYLITA: The town was built on top of

something called
the Phlegraean Fields,

which, at first glance,
doesn't look like much.

DAN: But for kilometres underground
and under the water,

this "field" is festering with steam
and pools of boiling mud.

CYLITA: And the reason this happens
is that below the surface

this is one of the world's 20 or so
known super volcanoes.

GUY: If, and frankly when,
this volcano erupts,

it would likely be of a volume
thousands of times more powerful

than a regular volcano.

DAN: We're potentially talking
about an explosion

of hundreds of cubic kilometres
of material.

CYLITA: It would be so big
that it would make the eruption

that destroyed Pompeii
look miniscule.

GEORGE: With a conical-shaped
volcano, like Mount Vesuvius,

the eruption is pretty much always
going to spout from the peak.

But with these Phlegraean Fields,
the eruptions are random -

they can come
from pretty much anywhere.

SHEILA: Thankfully,
this super volcano

hasn't had a major eruption
in centuries.

And so isn't the reason
parts of Baiae are underwater.

NARRATOR: If a massive eruption
didn't lead to the sinking

of this Roman vacation spot,
what did?

NATASHA: A disaster did strike Baiae

and it has to do
with seismic activity,

but unlike the destruction
at Pompeii,

it happened relatively slowly,
over hundreds of years.

CYLITA: It's a phenomenon
known as bradyseism.

And it's what's caused
half of this beautiful city

to find itself underwater.

DAN:
Sometime in the 3rd or 4th century,

underground magma chambers
started to empty.

And over time, that made
the ground above them sink.

NARRATOR: But incredibly this
sinking process seems to be...

reversing.

DAN: When the magma chambers empty,

the Earth's crust slowly falls,
that's called negative bradyseism.

And when they fill up,
causing the Earth to slowly rise,

that's positive bradyseism.

CYLITA: And it appears that that's
what's happening now, albeit slowly.

The gradual refilling
of these chambers

has so far brought
the submerged ruins

back towards the surface,
by something like six feet!

GUY: Now, it may not happen
in our lifetime,

but one day,
that once great city of Baiae

might just return to the surface.

NARRATOR: In the Gulf of Mexico,
nearly 200km

off the coast of Florida,
is a small group of sandy islands.

It's an area steeped in history
and shrouded in mystery.

This is Dry Tortugas National Park.

KAREN: These keys were discovered
in the early 1600th Century

by Spanish explorer Ponce De Leon.

CYLITA: After finding the islands
brimming with wildlife,

he named them Las Islas de Tortugas

or "The Islands of Turtles".

TORRI: The location is home
to historical Fort Jefferson,

and has been a significant site
throughout American history.

NARRATOR: And it's here,
from high above Fort Jefferson

and the small cluster of sand keys

that a new mystery unfolds.

In 2016,
while flying over Dry Tortugas,

a park employee catches
a glimpse of something strange

just below the surface of the sea.

- I was looking at the water,

and so while we were passing over,
close to the fort,

I happened to spot
a pattern in the water.

And then I see a series of dots.

And the dots were very geometrically
shaped, almost like a square.

As an archaeologist,

I've been taught to pay attention
to patterns in nature.

Oftentimes, it's worth another look.

CYLITA: What is this square pattern
in the water?

It definitely doesn't appear
to be a natural formation.

TORRI: How long
has it been sitting here?

And how many people have flown over
this same spot and missed it?

GUY: Now, it's not everyday
that you look out from an aeroplane

and you discover an entire mystery!

NARRATOR: But it wouldn't be
the first time that secrets

have been revealed
in the depths of these waters.

GUY: Dry Tortugas sits

in the middle of an area
rich in maritime history,

and it's a known hotspot
for historic shipwrecks

and even lost treasure.

KAREN: Ever since the Spanish landed
here in the 1500s,

the area has been
a major shipping channel.

- But Dry Tortugas sits in
the middle of fairly shallow water,

full of coral and rocks.

So, hundreds of years ago
when you factor in stormy weather,

strong currents,
and a lack of reliable maps

and navigational systems,
this often proved to be disastrous.

- To put it simply,
this place is a ship trap.

KAREN: Dry Tortugas,
and the surrounding area,

is littered with sunken vessels.

Since the 16th century,

there have been more than
250 documented shipwrecks.

NARRATOR: Including one of the worst
maritime catastrophes in history.

TORRI: In the 1620s,
a fleet of Spanish ships -

loaded with treasure -

left from Havana, Cuba,
heading back to Spain,

when they were hit
by a powerful hurricane.

CYLITA: Seven ships were sunk
in the storm,

and hundreds of people were lost,

along with the massive
cargo containing

gold, silver and some
of the finest emeralds in the world.

KAREN: The Spanish were able to
retrieve some of the lost treasure.

But one vessel,
the Nuestra Senora de Atocha,

was lost for over 300 years.

GUY: But in the 1980s, it was
discovered by a treasure hunter

named Mel Fisher.

Now, he managed to find remains
of the shipwreck,

along with what's been called
"the Atocha Motherlode".

Now, that is a cache valued
at a whopping

450 million dollars.

CYLITA: Even still, it's estimated
that Fisher only found

about half of the sunken treasure.

So, much of it
may still be out there.

NARRATOR: Could this strange pattern
- seen from above -

be the sign of a lost shipwreck?

Even underwater treasure?

Or could it be
something else altogether?

This is exactly what Josh Marano was
determined to discover

when he set out with a dive team
to get a closer look.

- The first thing
that we actually found was

a single post in the ground.

And then we found another one,
and another one.

NARRATOR: The mysterious
underwater posts were clearly

what created the square pattern
seen from above.

JOSH: I honestly expected it
to be the remains of a lighthouse -

some kind of tower that
was constructed on the water

to warn mariners away
from shallow areas.

NARRATOR: But during their survey,
the team discovers something else.

Covered in weeds and sediment,
a large stone slab.

- The stone was greywacke,
a type of dark sandstone.

GUY: Now, greywacke is a material
that was used in the construction

of Fort Jefferson,
primarily as flooring.

So, I'm wondering could
this somehow be related to that?

NARRATOR: Far from lost treasure
are the submerged posts and stone

nothing more than scrap material
from the fort's construction?

But a closer look revealed
something surprising.

The stone had something inscribed
onto its surface, a name -

John Greer.

JOSH: And it actually had a date
of death - November 5th 1861.

NARRATOR: What the team had found
was a gravestone.

- Initially discovering
the gravestone, I think,

everybody was just in
a state of shock.

We really did not expect
to find anything like that.

NARRATOR: What began
as a discovery from above,

quickly lead
to an eerie mystery down below.

- Who was John Greer?

- And why is his tombstone
in the middle of the Gulf of Mexico?

NARRATOR: Is it possible that nearby
Fort Jefferson holds a key?

GUY: Fort Jefferson is
a massive coastal fortress.

And it's built right on top of one
of the sand keys at Dry Tortugas.

CYLITA: The fort covers
approximately 10 acres

and is made up of more than
16 million bricks!

- It was built to last,
and for good reason.

TORRI:
Florida was primarily ruled by Spain

from the 16th to 19th centuries.

And it was only acquired
by the United States in 1819.

KAREN: Planning for fortification
began almost immediately

after the Americans obtained
control of the area.

CYLITA: This location was considered
an important strategic point

for controlling the Straits
of Florida and the Gulf of Mexico.

GUY: And the primary objective,
at least initially,

was to ward off pirates.

You have, for hundreds of years,

pirates and mercenary ships
roaming the area,

attacking merchant vessels
all along the coast of Florida.

CYLITA: So, in the 1840s,

the Americans got to work
on building Fort Jefferson.

GUY: But in the early 1860s,

we see the start
of the American Civil War.

And, of course, the Union
in the north does not want the fort

to fall into the hands
of the rebels in the south.

KAREN: So, they sent men down
to not only protect Fort Jefferson,

but also to work to bolster its
security and improve its defences.

TORRI: Now, over the course
of the Civil War,

Fort Jefferson was also
used as a military prison.

In fact, by the end of the war,
there were more prisoners

living there than soldiers.

KAREN: And the surrounding islands
were used to accommodate

military personnel,
workers, their families

and enslaved people, among others.

- So, these small sandy keys were
becoming increasingly populated.

NARRATOR: Was John Greer among those
who made up the growing population

at Dry Tortugas?

- We had a name
and we had something to go to

and actually go back
into the archives and research more.

And so John Greer was labelled
as a quote, "white labourer"

on payroll records at the time.

And he was employed primarily
as a carpenter,

basically working to build the fort.

CYLITA: But how did John Greer die?

And why is his gravestone
underwater?

NARRATOR: Is it possible
that his death had something to do

with a known killer on the islands?

GUY: You have outbreaks
of Yellow Fever

hitting the United States
several times during

the 18th and 19th centuries.

CYLITA: Yellow Fever is
a mosquito-borne disease

that was brought over
from the Caribbean via ships.

TORRI: And it caused absolute panic
in the United States,

not to mention
100 to 150 thousand deaths.

KAREN: As the number of people
at Fort Jefferson grew,

so did the risk of spreading
and contracting this deadly disease.

GUY: Outbreaks at Fort Jefferson
killed scores of people

throughout the 1860s and 1870s.

TORRI: To deal with this problem,
some of the other islands

in Dry Tortugas were used to build
makeshift quarantine hospitals.

CYLITA: This was good thinking.

Isolating the sick on other islands

likely saved hundreds
of others from dying.

NARRATOR: Is it possible that John
Greer was an unfortunate casualty

of this deadly outbreak?

- We did suspect that maybe
he's a yellow fever victim,

but we have not been able to find
any record of him in the hospital.

The very last record of him
at Dry Tortugas

was actually a record where he did
not pick up his last paycheque.

And that was November 1st of 1861.

Maybe he died in a more violent
manner, maybe a work site accident?

But until we do additional research,

we may not know exactly
how Mr Greer passed.

NARRATOR: While the circumstances
surrounding his death are murky,

something else remains unclear,

why his tombstone
was found underwater.

What other clues might be found
with a view from above?

CYLITA: When you take a look
at Dry Tortugas today,

it's made up of 6 or so islands.

But this wasn't always the case.

KAREN: When Ponce de Leon
first arrived here in the 1500s,

there were actually eleven islands!

JOSH: These are very dynamic,
very mobile sand islands

that move almost constantly.

In fact, the only reason that some
of the islands are still in place

is because of the structures
that were built on top of them.

CYLITA:
The sand keys of Dry Tortugas

are constantly changing
in size and shape,

and the number of distinct land
masses continually varies.

TORRI: These changes are caused
- in part -

by the effects of climate change,

as well as major storm
events and hurricanes.

KAREN: And, over time,
some of these sand keys

have eroded to a point

where they've disappeared
beneath the waves.

NARRATOR: Could this submerged
archaeological site,

with its strange pattern of posts
and mysterious tombstone,

be the location of a former island?

JOSH: I immediately went back
to historic charts of the area

and was able to figure out pretty
quickly that there was a structure

on what was formally an island,
but that structure

was not a lighthouse,
but it was actually a hospital.

And that island has not been
above water

for about the last 100 years.

They had actually described building
a quarantine hospital

in that location
with very specific measurements.

It was 30 by 34-foot stilt structure

that was, quote, "hurricane proof".

NARRATOR: With this
historical information in hand,

the research team could reference
satellite imagery from Google Earth

and measure the pattern of posts,

and sure enough,
they measured 9 by 10 meters.

The same dimension
as the former hospital building.

JOSH: So this island was one
of the ones that they utilised

to try to pull sick individuals away
from the fortification

and prevent them from infecting
one of the 2,000 other individuals,

either garrisoned or imprisoned
within the fort.

NARRATOR: And the archives turned up
other documentation from the keys

including photographs
from the island.

Showing that at one time this was
one of Fort Jefferson's Cemeteries

and home to dozens of graves.

- And now that we have been able
to do some more background research,

we've been able to determine
that there's more than 70 people

in the water at that location.

And so, for me personally,
it scores pretty high in my career.

I don't think I'll be able
to beat this easily.

TORRI: It's a bit eerie to think
about this 19th century cemetery

hidden underwater.

That dozens more gravesites
are likely resting here,

waiting to be discovered.

CYLITA: It amazes me that had
the pattern of posts

not been seen from above,

the memory of this former
island hospital

and the people interred here

may have been
completely lost to time.

KAREN: With its history
of shipwrecks and naval disasters,

this area sadly made a watery grave
for hundreds of people.

And ironically, even those who were
once buried here on dry land

have, ultimately, had
their final resting places

reclaimed by the surrounding sea.

NARRATOR: In a remote pocket of the
North Pacific Ocean,

not far from the Hawaiian islands

and more than a kilometre
below the surface...

..spotlights from a remotely
operated vehicle

Illuminate something truly bizarre.

- What on Earth is that?

- Is that a yellow brick road?

- Are Dorothy and Toto about to show
up at the bottom of the ocean?

NARRATOR: Aboard a mothership
at the surface,

scientists watching a live feed
are just as astounded.

SCIENTISTS: (ON RADIO) Woah!
- Wow, look at that!

- What is that?

- The yellow brick road?
- This is the yellow brick road.

NARRATOR: This peculiar pathway
was discovered in 2022

in the Papahanaumokuakea Marine
National Monument.

- Say that three times fast!

- What it is, is one of the largest

protected conservation areas
in the world.

DAN: It covers roughly 1.5 million
square kilometres

of the bottom of the Pacific ocean.

That is about the same size
as the state of Alaska - it's big.

GEORGE: It's home to the most
beautiful and bizarre creatures -

like gulper eels and anglerfish.

- There are stunning corals,
and strange rock formations.

NARRATOR: And this mysterious
yellow brick road.

NATASHA:
It was discovered by researchers

with the Nautilus Exploration
Program,

which is this amazing initiative
to survey,

map and study the ocean.

DAN: For more than 10 years

scientists have been exploring
different areas,

and my favourite part of all this
is that most of the time

when they send remotely operated
vehicle down there on a mission,

they livestream it so anyone in the
world can get in on the adventure.

SHEILA: We know so little
about the ocean,

despite the fact that it really is
the lifeblood of our planet.

DAN: Some of the things
they've found are beautiful,

and some of them
are downright strange.

Here's a perfect example of strange
- a yellow brick road!

NATASHA: The road is located
at the top of a seamount

which is a fancy word
for an underwater mountain.

TORRI: Now, when video of it
was posted online

it caused quite a frenzy -

lots of comments about
it being the lost road to Atlantis,

a path to sunken treasure
and extreme riches.

DAN: I can tell you this
- no treasure was found nearby,

but maybe
it's an archaeological treasure.

NARRATOR: Could this
'yellow brick road' be evidence

of human engineering, hidden
beneath the ocean for years?

Perhaps a clue can be found
in the Caribbean Sea

just off the coast
of southeastern Jamaica

where divers capture
underwater footage

of a sight
that looks eerily familiar.

- This also looks a lot like
our Yellow Brick road.

- If it is a road, how old is it?

SHEILA: The site lies just offshore

near a small Jamaican
fishing village called Port Royal.

GEORGE: While Port Royal is
a sleepy fishing town now,

it was once
a bustling port and trading post.

And a very important one.

NATASHA: In the 1600s,
Port Royal was a major economic hub,

controlled by the English.

TORRI: But one day, in 1692,

this booming trade hub
came crashing down. Literally.

- A powerful earthquake sent three
massive shocks through the town

followed by an enormous tsunami.

NATASHA: It only took a few minutes,

but when it was over,

most of the town
had been consumed by the sea.

SHEILA: It's estimated that
the event killed 5,000 people.

2,000 perished instantly

and the rest died soon after,
from related injuries and illness.

GEORGE: Over 30-acres
of the original 51-acre town

sank under the waves,
some parts as deep as 35 feet.

And they're still here,
under the water.

NARRATOR: The remains
of a once-bustling trade port,

hidden below the surface
for over three centuries.

Could a similar disaster have led
to this underwater mystery?

TORRI: This Yellow Brick Road
differs from the underwater ruins

at Port Royal in a couple
of significant ways.

First, it's more than
80 times deeper

and it's smack dab
in the middle of the ocean.

This isn't a road
that ever existed on land -

it's got to be something else.

NARRATOR: If this
yellow brick road wasn't part

of an earlier human settlement,

is it possibly a natural formation?

- And if so how was it made?

SHEILA: Is Mother Nature capable
of creating geometric shapes

like these "bricks"?

Absolutely. When you look closely,
you start to notice it everywhere.

GEORGE: Sometimes these geometric
formations are incredibly small,

and other times you find patterns
that are unbelievably large.

NARRATOR:
Like on the island of Tasmania,

where the view from above reveals
rectangular formations

that look strikingly similar
to the yellow brick road.

NATASHA: This patterned slab of rock
is located in Pirate's Bay

on the Tasman Peninsula.

SHEILA: In the 1800s,

the Tasman Peninsula
was best known as a penal colony -

housing hardened criminals -
now it is a nature lover's paradise.

- One of the big draws for outdoor
enthusiasts and photographers

is the tessellated pavement
in Pirate's Cove.

NARRATOR:
This 'tessellated pavement'

began to take shape
millions of years ago

when a flat slab of siltstone

was fractured due to movements
in the Earth.

As salty sea water
poured over the rock,

it seeped into the cracks.

When the tide went out,
the water evaporated

and salt crystals formed.

Those growing crystals
exerted pressure on the rock

causing it to flake away,

leading to the exaggerated
brick-like appearance we see today.

DAN: This amazing natural feature
is the result of time, pressure,

salt and erosion.

So could those same elements be
at play with the yellow brick road?

TORRI: Given that
it's in the middle of the ocean

and over a thousand meters
below the surface,

it's more than likely
a natural formation.

NARRATOR: Perhaps a view above

the nearby Hawaiian islands
will offer answers.

Specifically, over the southeastern
shore of Hawai'i Island,

home to Kilauea.

GEORGE: Kilauea is one of
the world's most active volcanoes.

It's been rumbling and erupting
almost constantly for 40 years.

TORRI: Its last really big eruption
event was in 2018.

Lava was spewing 50 meters
in the air,

roads were swallowed and
more than 700 homes were destroyed.

NARRATOR:
Lava is a formidable force.

But there is one thing powerful
enough to stop it

in its fiery tracks, water.

GEORGE: When lava and water collide,
there are often explosions

and giant clouds of steam.

DAN: The lava can harden
into these incredible formations,

and the seamount
where the yellow brick road is found

is proof of that.

GEORGE: Seamounts are formed
when magma rises through cracks

in the Earth's crust
and erupts at the sea floor.

Eventually,
the volcanic activity subsides,

and what's left is
a mountain of hardened lava.

The seamount where
the yellow brick road is located

is millions of years old,

but if you really want
to appreciate how it formed,

you can pop down
to the South Pacific where magma

is rising through
the Earth's crust right now

at an active undersea volcano.

TORRI: The Kavachi Volcano
clearly demonstrates

that when lava and water meet,

explosive things happen.

DAN: This is one of the most active
undersea volcanoes in the world.

The first recorded eruption
was in 1939,

and there have been
nearly 40 eruptions since.

GEORGE: Sometimes you can see
volcanic steam and ash

blast through the surface
of the water,

other times scientists
know it's erupting

by looking at satellite images that
show discoloration in the water.

NARRATOR: The collision of lava and
water can create a whole host

of incredible formations...

large seamounts
and underwater volcanoes,

to more delicately shaped towers,
caves and vents.

GEORGE: But the bottom line
is that mother nature can create

magnificent sculptures
when she combines water and lava.

NARRATOR: Even a yellow brick road?

GEORGE: We know this is natural,

but I've never seen underwater rocks
this colour and shape before.

DAN: This combination of colours
and shapes is unique,

but if you look
at those elements separately,

you can see that other structures
in the area have similar features.

SHEILA: This cliff face
at a neighbouring seamount

has similar colouration.

And this basalt rock has
a well defined brick-like pattern.

The yellow brick road
was only found recently.

As far as scientific discoveries go,
it's a baby.

PETER: Some of our planet's
most unique features

are studied for years

before scientists can say
exactly what they are,

or how they came to be.

TORRI: No one is ready to say
with 100% confidence

what this yellow brick road is,

but based on known science, there
are some probable explanations.

DAN: At some point,
millions of years ago,

scorching lava likely
came into contact with water

and then rapidly cooled
in a process called quenching.

TORRI: As it cooled and solidified,

fractures would appear giving
it its brick-like appearance.

It's sort of like when mud dries,
hardens and cracks.

GEORGE: Over time,
the surface of the hardened lava

might have experienced
a chemical reaction,

similar to when rust forms on metal,

that resulted
in its distinctive yellow hue.

This yellow brick road
is another one

of Mother Nature's
incredible masterpieces.

TORRI: As humans continue to study
the seafloor from above,

who knows what we'll find.

DAN: The ocean covers about 70%
of the planet's surface,

and we've only explored
about 5% of it.

Honestly, that's one of the most

exciting things
about the world today.

Everybody's obsessed with Mars,

but we haven't even finished
exploring the Earth yet.

It's amazing.

NARRATOR: The view above Australia

reveals something curious
off the coast.

Scattered throughout the blue waters
of the Gulf of Carpentaria,

a series of unusual structures.

- They appear to be
some sort of rock formation.

DAN: It also looks like they're
partially submerged in the water.

Some of these things
have been measured at a metre high

and over 280 meters long.

NARRATOR: In all,
over 300 of these formations

have been discovered
along Australia's shores.

And as the view from above reveals,

they don't seem to be limited
to the country's coastlines.

600 kilometres inland from Sydney,

in New South Wales, satellite
imagery reveals similar shapes,

this time, found within a river
known as the Barwon.

DSN: At this site, the shapes
seem to stretch and snake

along the riverbed
for about a half kilometre.

NARRATOR:
With a closer look via drone,

the shapes appear to be made
from thousands of stones.

GUY: The assumption would be that
these things, whatever they are,

are the work of people.

But, as we know, nature is also
very capable of creating

very sophisticated
shapes and patterns.

NARRATOR: Take, for example,
another mysterious phenomenon

found in Burnt Cape,
Newfoundland, Canada.

CYLITA: These have been called
"frost polygons",

and they're made
from thousands of piled-up stones

forming these geometric shapes.

DAN: The reason
they're called frost polygons

is because they're found in northern
or Arctic areas of permafrost.

- Similar kinds
of "patterned ground"

can be found in parts of Iceland,

as well as Norway's
Svalbard archipelago.

GUY: But they almost look too
perfect to be natural formations.

But that is exactly what they are.

NARRATOR: In the colder months, the
ground surface freezes and cracks.

And in the warmer months,
these cracks fill with water,

which collects and freezes
in the permafrost below.

Over time, these ice wedges
cause a buckling at the surface

creating these geometric formations.

CYLITA: While Australia's climate
wouldn't produce frost polygons,

is it possible that the shapes
we're seeing are somehow

created by the environment?

NARRATOR: Another example
of nature's creative force

can be found in California's
Joshua Tree National Park.

PETER: These are known
as "broken terrace walls".

And while they look like
they may have been

cobbled together by a stone mason,

these are also natural formations.

DAN: The walls,
or "dikes" as they're known,

began millions of years ago

when molten magma pushed up
through cracks in the granite stone.

And when it hardens,
this molten rock is much tougher

than the granite surrounding it.

Over time,
when the rest of the bedrock

in the area gets eroded away,

these strips of tough rock
are all that's left behind.

NARRATOR: But the stone formations
found across Australia's waters

are made up of individual stones

that seem
to have been stacked by hand.

Is it possible
they were built by people?

GUY: As the view
from above shows us,

humans around the world
have been building rock formations

for thousands of years.

NARRATOR:
Just south-west of Joshua Tree

is Anza-Borrego Desert State Park,

where the view from above uncovers
more striking rock formations.

Dotting the desert landscape are
some 500 mysterious stone circles.

DAN: The remnants of these stone
formations vary in size from

approximately five to twelve feet
in diameter.

NARRATOR: And while this park
is nearly the size

of the state of Rhode Island,

these hundreds of circles
are concentrated to an area

just over 15 square kilometres.

KAREN: No one is quite sure
how old these ring-shapes are,

but it's believed that they were
built by Native Americans,

thousands of years ago.

GUY: Now, the reason for making
these circles isn't entirely clear,

but past theories have suggested
they might have been used as kind of

ritualistic or ceremonial sites.

ANTHEA: But current thinking is
that they may have been

used by early hunter-gatherers

as places to rest
and take overnight shelter.

CYLITA: And for this reason,
they've come to be known, by some,

as "sleeping circles".

ANTHEA: Some have estimated
that they could be anywhere from

two to ten thousand years old.

DAN: If people did build
these rock formations in Australia,

it seems unlikely
that they functioned

as shelters or ceremonial sites,

because they are all offshore
or in riverbeds.

- But seeing as how people
have been using stone, well,

since the stone age,
how old might these structures be?

GUY: So far, radiocarbon testing
has proven really quite difficult,

and no one has been able to date
the formations

with any reliable measure
of accuracy.

CYLITA: But locals in Brewarrina,
right next to the Barwon River,

will tell you the stone structures
were built by people

a very long time ago.

DAN: The belief is
that these formations

could be as old as 40,000 years!

- If true, that would make them
some of the oldest-known

human-made structures on the planet!

DAN: There isn't definitive
radiocarbon dating,

but archeologists believe that the
structures were built more recently.

Probably within
the last 1,000 to 3,000 years.

ANTHEA: Either way,
these are still very old

with many of them being linked to
Pre-colonial Aboriginal communities.

KAREN: But the question remains:
What are they?

And what were they used for?

GUY: As we know, people have been
building stone formations forever,

and for various reasons. You know,

you have religious
and ceremonial sites,

you've got astrological calendars
and you've got ancient dwellings.

But there's also another
important reason.

NARRATOR: From the waters of
Australia to the deserts of Jordan,

the view from above
may once again offer a clue.

DAN: This is the Harrat al-Sham,

also known as the Black Desert.

It's a vast volcanic field covering
more than 40,000 square kilometres.

GUY: And this black desert is home

to some
fascinating stone structures.

KAREN: While they don't look like
much from the ground,

the view from above
reveals a network

of thousands of these massive
stone-built formations.

CYLITA: They've been called
"Desert kites"

because their shape almost looks
like a children's kite,

especially when viewed from above.

And they're not dissimilar
to the shapes in Australia.

DAN: The kites are believed
to be Neolithic,

potentially dating back
as far as 7,000 BCE.

GUY: They remained a mystery
for years,

until researchers finally
discovered their purpose.

DAN: They're massive traps.

Used to hunt animals like gazelle
for food and for fur.

The low stone walls were built
to guide migrating herds

and funnel them straight into
the hands of neolithic hunters.

NARRATOR: While these
stone-structures in Australia

were built into water,

is it possible that they exist
for a similar purpose?

- Now, it turns out that
these are also ancient traps!

But these ones
are designed to capture fish

and other marine animals.

CYLITA: The Ngemba tribe,
that's local to the Barwon River,

refers to these traps
as Baiame's Ngunnhu.

KAREN: According to tradition,

the creator Baiame brought
these traps into being

by throwing a giant net
across the river.

DAN: This is taken from oral history

that the inspiration for the traps'
design was taken from nature,

specifically from the pelican
and how it scoops fish up

with its large cup-like beak.

- You can see
this mirroring of nature,

in that many of the traps are built
in these cup-like U shapes.

DAN: And the U shapes are
all facing downstream

which would seem counter-intuitive
if you're trying to catch fish.

But that's because the fish here
are swimming upstream.

ANTHEA: So the fish swim upstream,
guided by the stone walls.

And then they land
in these holding ponds.

And it's here that the fish could be
speared, or even caught by hand.

DAN: Rocks could also
be placed strategically.

You could block
or unblock specific areas

and channel the fish
wherever you want.

- The beauty of these traps is that
they could be kept in place forever,

and when the gates were open,
fish could swim in and out freely.

- They were also designed
in such a way as not to inhibit

the natural flow of the river.

CYLITA: Based on local history
and tradition,

it's apparent that being
responsible stewards of the river

was extremely important.

NARRATOR: But what about
the similar formations

seen from above
the country's shorelines?

How did they work?

DAN: The traps found
along Australia's coasts,

these were designed to use tidal
fluctuations to achieve a catch.

ANTHEA:
The stone walls are built low enough

so that the fish can swim
into the trap at high tide,

but also high enough so that
some of the fish get trapped

in these stone-pens
when the tide goes back out.

CYLITA:
These Australian stone-walled traps

are a feat of engineering.

And their traditional use is

an example
of sustainable fishing practices

created in harmony with nature.

DAN: From the ground,

many of these ancient traps
would be totally missed.

It's only when you look at them from
above that you can fully appreciate

their scale and the ingenuity
of their ancient creators.

NARRATOR: From sprawling stone
fish traps in Australian waters,

to a yellow brick road
on the ocean floor;

an underwater cemetery

and luxurious Roman ruins -

kept hidden beneath the waves.

All hold keys to the past.

Mysteries uncovered
with a view from above.

Subtitles by Sky Access Services