All language subtitles for What.on.Earth.S10E06.1080p.DSCP.WEB-DL.AAC2.0.H.264-BTN_track3_[eng]

NARRATOR:
They're watching you.

More than 5,000 satellites
circle the Earth.

Every day, they uncover new,
mysterious phenomena

that defy explanation.

Witches, kings,
and mega weapons

in a 1,000-year-old forest.

Strange symbols have been
found here.

What is this?

NARRATOR: Decoding
the great plagues of Egypt.

It all happened
just a few miles

from where this image
is located.

NARRATOR: And the super warriors
of Voodoo Lake.

It was referred to as
the Sparta of Africa,

because this was a society of
brutal warriors.

NARRATOR: Baffling phenomena,
mysteries from space.

What on Earth are they?

[theme music playing]

NARRATOR: The New Forest,
South Central England,

a vast expanse of woodland
and wild gorse,

barely changed since
the Norman conquest of England

in 1066.

People haven't been
allowed to build here,

by royal decree,
for over 1,000 years.

NARRATOR:
Yet on June 5th, 2010,

an aerial LIDAR scanner
reveals remnants

of a seemingly man-made
structure buried

in a barren valley.

The image is really bizarre.

It's multiple concentric
circles made up of

a series of smaller circles,
really reminiscent

of a dartboard.

How long has this pattern
been there?

How many ages
has it been laying,

waiting to be discovered?

NARRATOR: Hooked
by the weird circles,

archaeologist
Rebecca Bradshaw is

trekking into the remote
forest, which is anything

but new.

BRADSHAW: The forest has this
extraordinary history.

It's a really ancient,
spiritual space.

NARRATOR: In 1079, King William
The Conqueror claims

this region as a royal
hunting ground.

Peasants are driven out,
threatened with death if

they disobey.

But death
finds William.

Two of the king's sons meet
their end here,

one slain by a hunter's arrow,
the other in a riding accident.

The locals said that
this was God's will

punishing him,
because he removed

13 churches and scattered all
the inhabitants,

making New Forest
almost barren of people.

NARRATOR: But some return and
make their mark on the woods,

leaving clues Bradshaw thinks
could shed

light on the LIDAR image.

Strange symbols
carved into trees and things

have been found here

and have confused a number of
historians looking to document

the history of the New Forest.

NARRATOR: In the 18th
and 19th centuries,

trees suitable for
shipbuilding are

carved with the king's mark,

a broad arrow.

But there are also
older carvings,

strange shapes, some of them
reminiscent of the LIDAR image,

the work of
medieval misfits,

spiritual outcasts who come to
convene with the ancient forest.

On some of these trees,

they found concentric
circles that

historians identify
as witches' marks.

A square has corners and edges,
whereas a circle doesn't,

and so it's a way of
capturing evil,

circumscribing evil into one
particular place.

NARRATOR:
Evidence of witches' marks

can be traced
to the early 1300s.

They are found in caves
and medieval buildings

across Britain,

scored in the wooden beams of
churches and domestic dwellings.

HYMEL: Witches would also carve
them into the ground,

from where they would then
conduct their spells.

HORTON: It is possible
that these concentric circles

we see in the LIDAR image

is an example of these
protection marks that you find

on trees and on buildings.

NARRATOR: But if these have
been left by witches,

they are massive.

The largest is almost
a mile wide.

They are of a size, scale,
and precision

that really suggests
a much more modern effort.

NARRATOR: Closing in on the site
scanned from the skies...

What is this?

...Bradshaw finds further
evidence that the strange

circles may be much more
recent in origin.

On first glance, this, to me,

looks like extremely
heavy duty concrete,

and the shape,
of course, suggests...

[sniffles]

a bunker.

This is a bit odd,
because it hasn't got

any visible

signs of where guns could go.

What is a non-defensive bunker
doing here

in the middle of a pretty
dense wooded area?

NARRATOR:
Climbing out of the trees,

Bradshaw reaches a vantage
point high above the valley

in the LIDAR image...

Well, well, well.

...where she finds
a bizarre clue

that literally points the way.

This

looks to me

like 100 feet in length
by sort of 30

to 40 feet wide,
and it is pointing directly

into this valley here.

This is crazy.

NARRATOR: Up close,
the giant arrow

serves no apparent purpose.

But Bradshaw considers
a fresh perspective.

If you're a pilot coming
through the skies,

you have indicators on
the ground like this arrow to

direct you where you're going,

then it would make sense
that those concentric circles

are actually a massive target.

NARRATOR: A mild descent
into the valley...

Wow!

...and Bradshaw's theory
hits the bull's eye.

This is a bomb crater.

I get the feeling that
this is a Second World War

bombing range.

NARRATOR: But this is
no ordinary bombing range.

The archaeologist estimates
the width

of the crater at 100 feet plus.

It could easily be
over 50 feet deep.

Something really
quite extraordinary

was dropped here to make
this size crater.

NARRATOR:
Bradshaw has found evidence of

a cataclysmic experiment that
rocked rural England.

What the British army did in
the New Forest

was secret then,
and had remained secret

for decades afterward.

Coming up, the mega blast
that changed history.

The Germans didn't know
what hit them.

NARRATOR:
And blood of the mummies.

KOUROUNIS: It looks like
some gigantic footprint

has just smashed
into the desert.

NARRATOR:
Archaeologist Rebecca Bradshaw

is in England's
ancient New Forest...

This is a Second World War
bombing range.

...investigating strange circles
revealed by LIDAR.

BRADSHAW: Something really
quite extraordinary

was dropped here to make
this size crater.

NARRATOR:
During World War II,

U.S. and British forces drop
around 1.5 million tons of

bombs on Germany.

A single raid

could see up to 1,000 planes

unleash their fury
on German cities.

So Hitler moves underground,

building impregnable
mega structures across

occupied Europe.

The Germans built a whole
series of structures that were

immune to all the bombs that
the British had then developed.

The most famous of these were
the submarine pens on

the French coast
at Saint-Nazaire,

with concrete ceilings
10 feet thick.

NARRATOR: To break through,
Britain needs

somewhere to test experimental
bombs in secret.

Empty by order of
William the Conqueror,

the remote
New Forest is ideal.

This LIDAR image
shows an essential

part of the Ashley Walk
Bombing Range.

NARRATOR: According to
declassified military records,

Ashley Walk becomes
operational in 1940.

Hell is soon raining down onto
vast chalk circles.

MORGAN: The concentric circles
in the image

were a method of evaluating
the effectiveness of extremely

powerful bombs.

You can measure the distance
from the epicenter of

the explosion,
and it allows you to determine

just how effective the weapon
is going to be.

The most important person
involved in this

testing was the legendary
scientist Barnes Wallis.

Dr. Wallis masterminds
the revolutionary bouncing bomb,

tested at Ashley Walk,

which wipes out two German
power stations beyond the reach

of conventional ordnance.

HYMEL: Thanks to Barnes Wallis,
these so-called

impregnable defenses
are no longer impregnable.

And Dr. Boom is just
warming up.

There's only one bomb that I
can think of that had enough

power to generate a crater
like this,

and that is a Tallboy.

NARRATOR: Wallis's six-ton
Tallboy is a game changer.

WALTERS:
It really was a big bomb.

In fact, it was what was known
as an earthquake bomb.

The earthquake bomb
didn't need precision.

It set off such giant
shockwaves that it would

destroy targets for hundreds,

if not thousands,
of yards around.

NARRATOR: The Tallboy,
tested at the LIDAR site,

is first deployed
in June 1944.

854 will fall by

the end of the war,

wiping out bridges, dams,
and V-1 launch sites.

ANNOUNCER:
We see the Tirpitz firing

back at them with 15-inch guns.

NARRATOR:
Tallboys also sink

Hitler's prime battleship,
the Tirpitz.

ANNOUNCER: Watch for
the 12,000-pounder

that stopped those guns
once and for all.

NARRATOR:
While at the New Forest,

Wallis is preparing to
test something even bigger.

I mean,
look at this extremely

heavy duty concrete
and this rebar here.

Really designed
to take a hit.

I'm willing to bet that
another type of earthquake bomb

was also being tested here, and
that's called the Grand Slam.

NARRATOR:
Weighing more than some tanks,

the Grand Slam is nicknamed
Ten Ton Tess,

and she's devastating.

The Grand Slam
was only tested once before

it was used over Nazi Germany,
and it was tested here in

the New Forest,

and that was one of the biggest
explosions that's ever

happened in the British Isles.

NARRATOR: On March 13th, 1945,

an experimental Grand Slam
smashes into the targets on

the LIDAR image
at 700 miles an hour.

Nine seconds later, it explodes,
triggering a massive

artificial earthquake.

SILBEY: The test of
the Grand Slam bomb

was so successful, the Allied
High Command decided to send

the bomb into action
the very next day.

They took out viaducts,
coastal defenses,

even submarine pens.

The Germans didn't know
what hit them.

They thought their sub pens

and their batteries were
completely impregnable.

The Grand Slam bomb was
incredibly effective at

destroying Nazi architecture

and infrastructure and really
helped turn the tide of

the war.

SILBEY: As soon as the Americans
saw the success of

this new kind of British weapon,

they created their own
version, the T-12 Cloudmaker.

NARRATOR: Twice the size
of the Grand Slam,

the 20-ton Cloudmaker never
sees action,

as it is quickly superseded by
nuclear weapons,

but earthquake bombs make
an earth-shattering

comeback in the run up to
the 1991 Gulf War.

Iraqi despot, Saddam Hussein,
has read Hitler's playbook

and built a fortified
mega bunker underground.

The United States deploys this
new weapon called the GBU-28,

which is gonna become known
as the bunker buster.

SILBEY: The GBU-28
destroyed the Iraqi bunker.

At its basic level,

it was identical in effect
to what Barnes Wallis

had started back in
the Second World War.

I don't want to imagine
a World War II

that didn't have
a Barnes Wallis on our side.

I put him up there with, like,
Alan Turing, for example.

These people who,
through genius,

helped to win the war.

NARRATOR: Barnes Wallis's genius
and the secrets of

the New Forest have been
exposed from the skies.

But what else lurks
beneath these

ancient woodlands remains
to be discovered.

Given the top secret
clandestine nature of

this site, it may be
that we never know.

NARRATOR: Coming up, the wrath
of the female super soldiers.

HORTON: They were disciplined,
organized,

and highly successful.

And mummies, Romans,
and biblical plagues.

And that's what
we're seeing from satellite.

NARRATOR:
June 30, 2019.

Eyes in the sky over Egypt

scan a valley 50 miles
northwest of Cairo.

We're seeing a beige ground,
what you'd expect to see,

but then in the middle
is this strange shape.

KOUROUNIS: It almost looks like
some gigantic footprint has

just come down
and smashed into the desert.

NARRATOR: The mega-sized
print covers around

eight million square feet
of the valley floor.

It's as if the earth
has been bleeding,

but the wound
closed up and dried.

KOUROUNIS:
Looking a little closer,

it has all the characteristics
of a dried lake bed.

It's not just
the shape that's unusual,

it's the color.

Maybe we're seeing
some mineral that was

left over when
the lake dried up.

NARRATOR: Historical records
confirm the presence of

a unique mineral in the lake

that could partly explain
its weird coloration,

one that played a key role

in the two greatest
civilizations of antiquity.

It just so happens that
this lake is covered

in a layer of sulfate deposits
known as natron.

NARRATOR: Some 5 and a half
thousand years ago,

the ancient Egyptians
begin mummifying their dead.

They encase the cadavers in
natron, harvested from

the country's desert lakes,

to dry out the corpse,
preserving it for the afterlife.

These natron lakes are
very alkaline,

meaning these are harsh to
most forms of life, and that's

what we're seeing
from satellite.

NARRATOR:
Natron from the lake

in the image was likely used to
entomb many of the great

pharaohs and high priests
of ancient Egypt.

During the reign of Cleopatra,

Egypt falls under the rule of
Rome, and the mineral is

put to a very different use,
one that transforms the world.

The sailors were using natron
blocks to support

their cooking pots
on the beach, and the heat

of the flames
caused the blocks to melt,

producing glass.

And as these little streams
of glass

are coming out from under
the fire, boom,

the glass industry is born.

NARRATOR:
For much of antiquity,

glass was as expensive as gold
and precious gems,

an indulgence reserved
for chieftains,

royalty,
and religious buildings.

The very first glass
is believed to

have been made in Mesopotamia
5,000 years ago.

That early period is almost
done with a small scale.

NARRATOR:
In around 30 BC,

the natron deposits in
the lake attract

Roman scientists,

alchemists in glass making,

who set up vast furnaces
around its shores.

Glass is mainly sand,
and there's

plenty of that out
in the desert.

Finding that resource,
no problem, but you need

a flux catalyst.

That's exactly what
we find here at this lake.

It was the Romans that
industrialized glass production

on a much bigger scale,

as glass then became
a consumer object that was

employed throughout the empire.

NARRATOR: Such is the value
of Roman glass

that it is traded
across the known world,

reaching as far as Afghanistan
and China.

We're not talking about, like,
some artisan making a couple

of glasses,
we're talking about glass slabs

weighing 20 tons that
could be shipped anywhere.

NARRATOR: The advent of glass
blowing enables the Romans to

form these giant blocks into
any shape or size,

revolutionizing the industry.

A single glass slab
manufactured from this site in

Egypt could have been
broken down

into thousands of pieces and
turned into tens of thousands

of individual bottles
and glasses.

HYMEL: It makes it cheaper
and more accessible

to a much larger population --
it just explodes.

NARRATOR:
For around 400 years,

the site spotted from space

is the focal point
of Roman glass production,

creating the windows that
adorn Rome's greatest buildings.

And putting bottles on
the tables of the empire's

65 million citizens.

Yet the presence of natron
only explains

part of the lake's
strange appearance.

HORTON: Natron is a mineral salt
that's naturally

white or pale yellow.

So that raises the question,

what is this red deposit
that's also found on the lake?

NARRATOR: Mark Horton learns
that the caustic waters

that enticed the morticians
and glass makers

of Egypt and Rome
also attract aquatic

organisms in their
countless billions.

On the surface of this lake is
an algae that can live in

these extremely
hostile environments

and breeds and forms
this skin of pinky red on

the surface of
the white salt.

NARRATOR: When the algae blooms,
it produces red pigments,

creating giant patterns
on the natron lake.

These blooms also generate
toxins, which are lethal

to fish, birds, and humans,

toxins which could help
explain one of

the most famous mass deaths
in history.

There are Biblical stories
that speak

of a similar phenomenon.

God sent 10 plagues upon
Pharaoh and the Egyptians,

and one of those was to cause
the Nile to run blood red.

BELLINGER: The fish died,
the river stank,

the Egyptians couldn't drink
the water anymore,

and it all happened just a few
miles from where

this image is located.

NARRATOR: The same lake
that helped mummify

the Egyptians, carrying them
to the afterlife,

may have also been the cause
of their sickness and death.

Lots of legends are based on
nuggets of truth, and it's

entirely possible that
the Biblical tale

of the Nile running red could
have been caused by one of

these massive red
algal blooms.

NARRATOR: Coming up,
attack of the man hunters.

The Europeans are utterly
terrified of

these women warriors,
whom they called Amazons.

NARRATOR: And the Nazis'
secret terror weapon.

12,000 tons is enough to kill
millions and millions

of people.

NARRATOR:
October 12th, 2020.

A satellite scanning
the country of Benin

in West Africa

captures strange features
in a lake far below.

This is bizarre.

I don't see any roads,
I don't see any fields,

just homes, buildings,
and water.

It looks like
a settlement that's

just been overwhelmed by
an incoming flood.

HORTON: But looking
more carefully, I can see

that this is not
a flooded village,

but actually a village
that's been built

deliberately in a lake.

NARRATOR: This is Ganvie,
a giant floating village of some

3,000 raised structures
and the ancestral home

of the Tofinou people.

Yet what really intrigues
analysts is why the Tofinou

chose to build it here in
the first place.

BELLINGER: The Tofinou tribe
has, for generations,

been building over water,

and we know from
oral tradition that's for

an extraordinary reason.

NARRATOR: The story of
the strange lake village

begins in the 17th century.

At the time,

much of this region is dominated
by the Tofinou's rivals,

the Fon people, who ruled
the powerful Dahomey kingdom.

It was actually sometimes
referred to as the Sparta

of Africa, because this was
a society of brutal warriors.

Fon warriors developed
a fearsome reputation that

traveled far beyond
the borders of their kingdom.

NARRATOR: The Fon
rely heavily on forced labor,

and around 1/5 of
their kingdom's

one million strong population
are slaves.

This group of people use this
military brutality and prowess

to become very wealthy and
successful in the slave trade,

terrorizing any of the tribes
around them that they did not

have a relationship
or an agreement with.

HORTON: They were disciplined,
organized,

and highly successful.

NARRATOR: In 1720,
the Fon warriors push

south towards the site
in the image,

putting their king in contact
with European slavers.

In exchange for goods
and weapons,

he supplies them
with around 20 percent of

all the humans trafficked
across the Atlantic.

But years of raiding
neighboring states

deplete the number of male
Fon warriors,

and the kingdom's enemies
begin to close in.

This creates a cultural shift
for the Fon people

and through that,

their women become more
and more a part

of their combat force.

Women played a major role in
the military,

so much so that the king had
an elite group that served as

an all female royal guard.

NARRATOR: Such are the skill
and ferocity of

these female warriors that
between the 1760s and 1840s,

their ranks increase
from 600 to 6,000.

They're the only known
female fighting

force in the world
at this time.

The Europeans are utterly
terrified of

these women warriors,
whom they called Amazons.

Their specialty was pre-dawn
attacks on enemy villages,

and that was the most efficient

and effective way for them to
gather up slaves

to sell to the Europeans.

NARRATOR: The Fons' slaving
raids puts them in conflict with

the Tofinou people and explains
the construction of their giant

lake village
in the satellite image.

The Tofinou people didn't have
quite the warrior culture that

the Fon did,
but they were clever,

and they were observant,
and over time,

they look for weaknesses in
the Fon tactics and strategy.

One of the weaknesses they
found was a fear of the lake.

NARRATOR: The Tofinou know
that the Fon are

devotees of Vodun, the origin
of today's Voodoo.

They believe that
powerful, supernatural beings

inhabit nature and fear
vengeful water spirits.

According to Fon tradition,

a powerful demon walked
the waters of this lake,

and they would never do anything
to raise that demon's anger.

KOUROUNIS:
The Fon refused to attack

any structure
that was on water,

so the Tofinou built
their village on the water,

and suddenly, they were able to
use their own superstition

against them.

NARRATOR:
Over the following decades,

more Tofinou
move on to the lake

to escape persecution at
the hands of the Fon.

They become known
as the Water People.

KOUROUNIS: As long as
they lived on the water,

these villagers were
safe from attack

and were able to avoid being
sold into slavery.

They gave the name of
the village Ganvie,

which means, in the local
language, "We survived."

BELLINGER: And so the Tofinous
stayed and continued to build

and expand
this village on stilts

for many generations to come.

NARRATOR: 150 years after
the end of the slave trade,

the water village of Ganvie
continues to flourish,

a living monument to
one people's resilience in

the face of unspeakable terror.

JANULIS: To this day,
there are 20,000 Tofinou

still living on the lake,
just like their ancestors did,

who avoided being captured
by the Fon.

It's a very interesting,
very horrific history,

but one that needs told.

NARRATOR: Coming up,
monster tank face off.

It was one of the most
incredible battles

of World War II.

NARRATOR:
And the killer quarry.

It becomes
a warehouse of death.

NARRATOR:
October 9, 2018.

A camera in orbit over Ukraine
scans the city of Kharkiv.

WALTERS: What we're looking
at here

is a pretty grim-looking
industrial complex,

bit of a wasteland, frankly --

it's not a very inviting place.

NARRATOR: Yet lines of
objects hidden between

the desolate looking buildings
do invite attention.

CAVELL: Looking closer,
you can start to see

that these objects
actually have

some kind of a turret on them
and some sort of gun.

These are tanks.

These are armored
fighting vehicles,

and there are dozens
and dozens of them.

NARRATOR: Leaked photographs
confirm that the image

has captured
a monstrous metal graveyard,

containing the rusting remains
of hundreds of tanks.

WALTERS: You've got to
ask yourself why are there

so many tanks just sitting there
doing nothing.

Tanks should be out fighting.

This is just a huge tank park.

NARRATOR: Martin Morgan studies
the city's history for clues.

When I look into
original records,

I find that this is the old
Kharkiv tank factory.

This was the largest factory
for the production of armored

fighting vehicles during
the old Soviet Union

and the birthplace of
what was one of the greatest

fighting machines
of the 20th century.

NARRATOR: That fighting machine
is the T-34 tank.

The T-34 tank is one of the most
powerful weapons that

the Soviets wielded on

the battlefields of
the Second World War.

It's a part of every battle.

It's a part of
every Soviet victory,

and they're all made
at Kharkiv.

NARRATOR: The T-34's engine
and tracks are built to handle

mud and snow
on the battlefields

of the Eastern Front.

What's more, it has a more
powerful cannon and better

armor than German tanks,

but it's light enough to
outpace them

on the battlefield.

MORGAN: The T-34 is arguably
the finest tank of

the Second World War, because
it is the best of both worlds.

The Germans were scared as
hell of this vehicle,

and that speaks to just how
effective

the design really was.

NARRATOR:
The success of the T-34

forces the Nazis to deploy
the massive 54-ton Tiger.

In July 1943, vast numbers
of Russian and Nazi

tanks meet head-on at
the Battle of Kursk.

About 5,000 tanks will come to
this battle.

So it's the biggest tank
battle of all time,

including up to today.

You have tanks just rolling
towards each other, firing

massive shells back and forth.

I mean, it was -- it was
probably one of the...

most incredible battles of
World War II.

NARRATOR:
At the Battle of Kursk,

the Russians incur
devastating losses,

but the T-34s
ultimately prevail.

The Germans never recover from
this defeat,

and two years later,
the Soviets capture Berlin.

PAVELEC: Kursk is one of
the turning points that

solidifies the final retreats

and absolute route
of the Germans

off of the Eastern Front.

NARRATOR: Following the end
of World War II,

the Kharkiv Tank factory
continues to play a vital role

in Soviet military strategy.

MORGAN: There are over 60,000
workers that are producing

about 60 tanks a month at
this facility

during the height
of the Cold War.

[indistinct shouting]

NARRATOR: In 1991,
the Soviet Union collapses,

and countries like Ukraine
gain their independence.

Tanks stopped
rolling off

the Kharkiv factory line, and
its yards begin filling with

mothballed relics of
the country's communist past.

Yet recent analysis has
revealed renewed activity

at the site.

MORGAN: When we look at
satellite imagery,

we can see that tanks are kind
of coming and going from

the facility.

NARRATOR: It appears Ukraine has
once again turned to

the T-34 tank factory to help it
repel a foreign threat.

These tanks could well be part
of Ukraine's

absolutely justified efforts
to defend herself against

Putin's aggression.

NARRATOR: In 2014, Russian
President Vladimir Putin

[speaking Russian]

orders his troops to invade
Ukraine's Crimean Peninsula.

This triggers an ongoing war,

which has claimed over
13,000 lives.

The attack that Russia mounts
on the Crimea is forceful.

They come in with aircraft.

They come in with tanks,
they come in with ground troops.

NARRATOR:
In a twist of fate,

Russia is now fighting tanks
from the very factory

that helped it to defeat
Hitler all those years ago.

MORGAN: This image is full of
deep, contemporary ironies,

because it makes you confront
the way that the former

Soviet Union crumbled,
fell apart,

and the awkward,
intense new world that has been

created in its aftermath.

NARRATOR: Coming up,
magic lake.

It's as if the water
had been turned to oil.

NARRATOR: April 2017.

Satellites orbiting
over northern Europe

scan a quarry in England's
industrial heartlands

and uncover a mystery.

RUBEN: We're looking at what

looks like a rather
beautiful lagoon,

very vibrant blue.

And then you go
to the next image,

and it's black.

NARRATOR: The lagoon is vast,

43,000 square feet,

but its dramatic color change
has taken just a few hours.

It's as if the water had been
turned to oil.

That's what it looks like.

NARRATOR: This quarry is
called Harper Hill,

and it has a dark history that
could explain the lagoon's

weird transformation.
-PAVELEC: Interestingly,

this was a chemical weapons
storage facility before, during,

and after the Second World War.

Tens of thousands of chemical
weapons were stored here and in

the area surrounding it.

NARRATOR:
In 1938, Harper Hill Quarry

is chosen as the location

for a facility
code-named Maintenance Unit 28.

Over the following two years,

the British military use it to
conceal more than 45,000

different chemical weapons.

It becomes
a warehouse of death.

By 1940, it's the
largest chemical

weapons storage depot
in Britain.

NARRATOR: The warehouse of death
has its origins in the mud,

blood, and gore of
the battlefields of World War I.

JANULIS: World War I
was the first example

of truly industrial warfare,

and in 1915,
the first example of

chemical warfare
being utilized.

During World War I,
chemical weapons

kill or injure
over a million soldiers,

including a young
Adolf Hitler.

After World War I,
the Western countries decided

that chemical warfare
was so inhumane,

it should be banned,

but that didn't stop
all of these countries

from continuing to experiment
with chemical weapons.

NARRATOR: In 1938, German
scientists discover sarin,

a compound 20 times more
lethal than cyanide.

They go on to produce
12,000 tons of the nerve agent

during the war.

12,000 tons of sarin gas
is enough

to kill millions and millions
of people.

So places like Harper Hill
acted as

that storage point for
the captured chemical weaponry

at the end of World War II.

PAVELEC: Could it be that
there's chemical weapons

that were not
disposed of properly

that are now coming
to the surface and turning

the water black?

NARRATOR: When scientists
test the lagoon

in the image, they confirm it
is dangerously contaminated,

but it's a legacy of
a different era

in the quarry's history.

Chemical analysis
has shown that it's

actually got a really high
pH level.

KOUROUNIS: It's been measured
at a pH of 11.3.

Pure ammonia is about 11.6.

So this is nasty stuff.

NARRATOR:
Long before World War II,

the quarry produced vast
amounts of highly alkaline

quicklime.

During the 19th century,

it played a vital role in
creating the modern world.

JANULIS: Quicklime reacts
with certain elements

within molten metal,

basically getting
the impurities out,

causing them to aggregate,
creating slag that can be

easily removed
to get pure steel.

NARRATOR: Steel made using
quicklime fuels

what is known as the second
Industrial Revolution,

which transforms
the industries and landscapes of

England, the U.S., and beyond.

MORGAN: So many of the things
that we recognize as being part

of the greatness of modernity
are created during

this critical time period,

during
the Industrial Revolution.

NARRATOR:
In 1952, the quarry closes,

and it fills with water,

creating the lagoon in
the image.

That begins to explain a lot
about the color of this water.

That deep blue can come from
calcium carbonate

that leaches out of limestone.

KAYS: Now we understand why
it's so beautifully blue,

nut the question remains,
why did it suddenly turn black?

NARRATOR: As news of the azure
lagoon spreads,

it attracts thousands of
visitors, and its caustic waters

become fetid with all manner of
garbage and waste.

RUBEN: The blue color is
really beautiful,

but this lagoon has also been
used as a dumping ground for

the bodies of animals,
car wrecks,

whatever people have decided
to throw in there.

KOUROUNIS: The authorities
actively try to dissuade people

from swimming in these waters,

but all of the signs and
warnings have little effect.

So what do you do?

Well, the authorities have gone
to the extreme

steps of having to dye
the water black.

KAYS: They bought some dye.

They dumped it in, the next day,
when the revelers showed up to

hang out by their beautiful,

toxic blue lake, they found
the water had completely

changed color and was not
nearly as inviting.

The lesson here is

just because something
looks beautiful,

that doesn't mean you
should immediately

expose your entire body to it.