Original subtitles

Narrator: they're watching you.

More than 4,000 Satellites circle the earth.

Every day, they uncover new, Mysterious phenomena.

Some defy explanation.

Bam! This sticks out Like a sore thumb.

There must be something Very big and very bad.

Narrator: a giant dome spotted On a remote pacific island...

It looked Like something from

"Close encounters Of the third kind."

Narrator: A strange lunar landscape Off the coast of africa...

It's like nothing I've seen on earth.

Narrator: A huge scar cut into the remote Canadian wilderness...

You got to consider That this could be

Some kind of biological attack.

Narrator: baffling phenomena, Mysteries from space.

What on earth are they?

**

-- captions by vitac -- Www.Vitac.Com

Captions paid for by Discovery communications

July 12, 2013,

6-year-old Nathan woessner

Is out walking with his parents On the mount baldy sand dunes,

Along the shore of Lake michigan, indiana.

They are unaware Of the danger awaiting.

This looks like A nice place to go.

It's on the water. It's right by a town.

The idea that something Could happen here,

It's kind of crazy.

Narrator: what should have been A fun afternoon

By the lake will spark a Major scientific investigation,

Using state-of-the-art aerial

And satellite Imaging technology.

Porges: nathan woessner And his mother

Are walking across The sand dunes

Along lake michigan when --

When suddenly, He disappears.

Ah!

How does a boy Get swallowed up,

Virtually instantaneously, By a mound of sand?

Nathan? Nathan!

Sand dunes don't Just eat people.

What is going on here?

A 6-year-old boy From sterling, illinois,

Is trapped under crushing sand.

Narrator: nearby, Local geologist erin argyilan

Is out on the dunes, Taking wind speed measurements.

She sees the drama unfold.

Argyilan: he slid down, Out of sight.

And the hole filled In right behind him.

Help! Immediately, it was just panic.

And people were yelling And screaming

And digging in the sand.

Woman: my friend's son, He got stuck in a sand dune.

And he's, like, under the sand. And they can't get him out.

People were arriving From all different areas,

From the national lakeshore, From the local police,

From the fire department.

First excavator Wasn't able to even climb

A portion of the dune.

And at that point, I think Everyone felt pretty desperate

And, uh, disheartened.

There was definitely Concern and discussion

That this would probably Be a recovery

And not a rescue.

Narrator: it takes police And fire crews

More than 3 hours to dig down

And reach the trapped child.

Nathan was found around 11 feet Below the surface.

Narrator: the young boy is Brought out unconscious.

There was a lot of work Left to do,

Because someone who's Buried in the sand

Would have swallowed A lot of sand,

Which is very dangerous For their lungs.

Narrator: paramedics rush nathan To the hospital.

The near fatal ordeal Leaves a mystery.

How can a boy Simply disappear into the sand?

Analysts turned to satellite Imagery for clues.

Dark patches On the dunes

Around where nathan disappeared

Immediately arouse suspicions.

It's natural to think, Could this be quicksand?

Narrator: Quicksand can be deadly,

Especially around Coastal regions.

But there's a problem With the theory.

Quicksand typically occurs In low areas,

Where water collects and mixes

With the sand to produce This high viscosity quicksand.

But this is on the flank Of a high hill of sand.

If quicksand didn't Swallow nathan, what did?

Narrator: with satellite images Inconclusive,

Local geologist erin argyilan

Turns to ground-penetrating Radar

To look into The sand dune itself.

We've done quite a lot With ground-penetrating radar.

And it can actually show The underlying landscape.

Narrator: the radar reveals 66 potentially

Deadly holes lurking Within mount baldy.

Somehow, There are air pockets

All through this dune.

Narrator: the speed nathan Disappeared suggest

He fell into a shaft

Or hollow cavity beneath The surface of the sand.

But it's not clear What could make

Such large subterranean holes.

At the time of the incident,

There were rumors Of someone digging in the sand

Just before nathan disappears.

So could the holes Erin found be man-made?

Closer study of the sand On mount baldy reveals

It to be So fine-grained

That digging large holes Is near impossible.

You couldn't practically Dig by hand very deep

In a location like that, Essentially

Because the sand would Keep collapsing down on itself.

Narrator: to investigate The origin

Of the strange series Of holes,

Argyilan studies Satellite images

Dating back To the mid-twentieth century.

Using the data to create A computer simulation reveals

The sand dune is consuming The nearby forest.

Sand, by it's very nature,

Moves by virtue Of wind pushing it around.

And as that happens, The entire dune moves.

Mount baldy is definitely On the move.

It's been moving Since the 1940s.

And it's buried One parking lot

And is well on its way to Burying a second parking lot.

Narrator: mount baldy is covered With dead tree tops.

Argyilan believes These are the key

To explaining the holes Beneath the surface.

To test her hunch,

Argyilan turns to another Advanced imaging technology.

She takes to the sky, Using aircraft-mounted lidar.

This is a laser land Scanning system

Which generates precise

Three-dimensional Ground imagery.

Lidar imagery is Where you can

Actually reconstruct The elevation of landforms.

And if you have many images From many different years,

You can then reconstruct Your entire landscape.

Narrator: the aerial lidar Reveals the entire sand dune

Sits directly on top of a forest Of decaying trees.

Argyilan believes the hole That swallowed nathan

Is the hollowed out trunk Of a rotting tree.

Argyilan: this would've been A fully-grown, mature tree

That is rooted Into a landscape

With a soil that is about 3,500 years old.

Essentially, where nathan was Walking, there were trees

Like this completely Buried under the sand.

They are decomposing,

And oak trees in particular

Will decompose From the center outward.

Narrator: argyilan calls Her discovery

Dune decomposition chimneys.

These form a series Of hollow shafts

Which can extend more Than 10 feet deep.

Nathan fell into one Of these hollow tree trunks.

After 11 days in the hospital,

Nathan woessner makes A full recovery.

Today, nathan seems to be A thriving young boy

Without a lot of damage.

Narrator: the potentially deadly Cavities in mount baldy

Are still there,

Waiting for the footsteps Of the unwary.

**

A surveillance satellite Orbiting over the pacific ocean

Photographs a strange,

Circular shape On an isolated island.

How long has this been here? Is this ancient or modern?

From space, it looks A lot like something

From "Close encounters Of the third kind."

Narrator: september 2015, A satellite captures

The image of a bizarre Circular shape

On a remote island In the pacific ocean.

From space, it looks A lot like something

From "Close encounters Of the third kind."

You don't see anything Similar on the other islands.

Is it some kind of a launchpad That was never finished?

Narrator: a declassified Aerial photograph

Taken by The u.S. Defense agency

Revels more detail.

The circular structure Is a huge dome

Made of thick slabs of concrete.

Why would anyone build A perfect concrete dome

In the middle of nowhere?

Narrator: the images come from Just north of the equator,

From a remote group of islands

Known as the enewetak atoll.

This is a tiny island In the middle of nowhere.

No major cities nearby.

No populated centers.

Narrator: the concrete dome Is huge,

Spanning over 350 feet across.

And it's not alone.

Bizarrely, it sits next

To a deep blue hole In the water

With exactly The same dimensions.

The sheer scale of this Is impressive.

Narrator: two giant disk shapes, One on land, one in the sea.

A secret military base?

An abandoned rocket launch site?

The image poses a mystery.

At first glance, The dome shape

Strongly resembles known designs

For nuclear blast shelters.

Pavelec: this kind of dome

Is structurally very, Very strong.

It's the exact shape You would use

If you wanted to make Something very,

Very safe and durable.

Narrator: during the cold war,

Fear of nuclear annihilation

Drove the construction Of elaborate dome shelters

Called survival condos,

Accommodation for The end of the world.

**

Survival condos are basically

A multi-level hole In the ground built,

In a lot of cases, By people who were terrified

That we were going To have a nuclear war.

Narrator: the structure's Isolated location supports

The survival condo theory.

Pavelec: if you want to stay out Of the way of nuclear holocaust,

This would be a fantastic place To put a shelter.

Thousands and thousands of miles

Away from any civilization Or other targets.

Most of them are still In the ground,

But probably Have been abandoned.

Narrator: while the dome Does bear a strong resemblance

To some nuclear Fallout shelters,

Further analysis casts doubt On this theory.

There are problems with The doomsday shelter argument.

If you look really closely,

There's no way in Or out of this structure

And there are no air vents.

Narrator: Access to the enewetak atoll

Has been highly Restricted for decades,

Making it impossible to Inspect the structure up close.

But the images Offer further clues.

One of the striking things In this image

Is the massive Blue hole in the ocean

That's sort of the mirror Of this dome.

It doesn't look natural either.

Narrator: satellite images Reveal other deep holes

In the sea around Nearby islands.

Similar looking sinkholes Can occur naturally.

But documents from U.S. Military archives

Reveal a chilling secret:

This was the location of a major U.S. Atomic weapon test site.

The holes could Be bomb craters

Produced during one Of the darkest chapters

In the history Of global warfare.

If everything Goes according to plan,

We'll soon see The largest explosion

Ever set off On the face of the earth.

They started testing in 1948.

And they tested 43 Nuclear devices in the islands.

These were some of The biggest hydrogen bombs

The united states Has ever produced.

Narrator: the huge, Round holes

And the concrete dome itself

Could be directly connected To the testing

Of the world's largest Atom bombs.

Pavelec: In several of the tests,

They would explode The nuclear bomb

And see how far out it Would affect the ships.

Hansen: it required a huge Concentration of people.

You had soldiers all over The place to observe them.

And it extended through Almost 10 years.

So there's a lot Of activity going on.

Narrator: The scale of the operation

And the destructive power Of the bomb tests

Was at a level Never seen on our planet

Before or since.

Hansen: the biggest bomb Was called ivy mike,

Which was 500 times More powerful

Than the bombs dropped On hiroshima

And nagasaki in world war ii.

Narrator: some islands were Simply wiped off the map.

Man: elugelab Is completely calm.

Nothing there but water

And what appears To be a deep crater.

Narrator: if the holes Around the islands

Are craters left By atomic bombs,

Then the giant concrete dome Could be their grim legacy:

A storage dump For radioactive waste.

This much concentrated Atomic weapon testing

Is going To generate fallout,

But also a lot Of radioactive waste,

Including plutonium-239.

Hansen: When the bomb exploded,

That radiation was scattered

All over the place on the ground And in the water.

And the half-life of that Is 24 thousand years.

So that means That the radiation

Will stay very high For long periods of time.

Narrator: The radioactive debris

Threatens Surrounding islands.

Capps: It's not the sort of thing You want to box up on a ship

And bring home To the united states.

So could this dome be Where they stored that waste?

Narrator: Declassified records released

Under the freedom of information Act reveal the truth.

Pavelec: american scientists Very quickly figured out

That they needed To collect all this debris

And radioactive material And put it somewhere.

So eventually, the army corps Of engineers goes to enewetak.

They dig this huge pit.

They line it with concrete.

They throw a whole bunch Of radioactive material

In a big huge garbage can,

For want of a better term,

And they cap it off With a concrete dome

18 inches thick.

Narrator: sealed off From public access,

For decades the dome Has kept the island safe.

But recent Observations suggest

Cracks are now appearing In the concrete.

Hansen: there are concerns That there may be some leakage

Into the surrounding ocean.

If it's a slow leak, It probably won't mean anything.

But if -- If the thing splits

And all this stuff comes out,

That's a bad thing.

Narrator: the worldview ii Satellite captures

An image of a strange Pock-marked landscape

On an island Just off the coast of africa.

I'm trying to think Of what kind of force

Would be so powerful To create a landscape like this.

Honestly, I have no idea.

These c-shaped features Are really strange.

I'm not sure What they are.

Narrator: december, 2015.

The worldview ii Satellite photographs

A bizarre landscape Off the coast of africa.

The image baffles experts.

How strange. What are these things?

What kind of force Would be so powerful

To create a landscape like this?

Narrator: the image comes from The island of lanzarote,

80 miles west Of the african coast.

Image analyst amanda marketti Takes a closer look.

The image itself is both Weird and surprising.

It's like nothing I've seen on earth.

It almost looks Extraterrestrial.

Narrator: it might be possible The bizarre shapes

Are a perfectly Natural phenomenon,

A result of the islands Own explosive origin, volcanoes.

Lanzarote and all of The canary islands

Are volcanic islands.

You wonder, is this some Remnant of its violent birth?

Narrator: lanzarote emerged From the ocean

15 million years ago,

Born through huge Volcanic eruptions.

Brand: lanzarote sits on top Of a hot spot plume,

Which is where a massive Upwelling of heat

Within the earth melts The mantle, producing magma.

This magma can be 2,000 degrees centigrade.

Narrator: the volcanoes on the Island are currently silent,

But their heat still rages Beneath the surface.

Could the landscape Of round pits

Be volcanic vents, Known as fumarole?

Fumaroles are -- are very common In volcanic landscapes.

They are essentially Pathways through the crust

Where gas can escape.

Narrator: fumaroles often form Circular shapes in the ground.

But other features Seen in the image

Make this theory seem unlikely.

While you may find depressions Associated with fumaroles,

You're certainly Not going to find

C-shaped rims That surround them.

Narrator: if the strange pits Haven't been blasted out,

Maybe they've been bashed in.

Is this a field Of impact craters?

The last eruption Was only in 1824,

Which isn't that long ago.

Any time you have An explosive volcanic eruption,

It's likely that There will be projectiles

Ejected From the volcano.

Narrator: these projectiles Are called lava bombs.

When volcanoes erupt, Gases blast these lumps

Of rock high into the air

And crash down to earth, Forming craters.

They can be anywhere From fist-sized

To the size of a volkswagen bug.

Narrator: But in recent history,

None of the island's eruptions

Have been violent enough To produce a rain of lava bombs

To scar the land.

Clearly, something else Is to blame for these shapes.

Narrator: If they're not natural,

The pits must be man-made.

These features were built

To be extremely similar To one another.

They're at the same height,

And they're at The same position.

So that tells me that they're

All probably being used For the same purpose.

But what purpose that is, I don't know.

Narrator: it's possible That someone

Created this field Of c-shapes.

They would have to physically Transform the landscape.

And lanzarote was once home To an artist famous

For doing just that.

The artist cesar manrique

Was a pioneer Of large-scale land art.

His work can be found All over the island.

Manrique was famous for Creating huge architectural art

From natural Volcanic landscapes.

For several projects,

Manrique planted trees Inside giant lava domes.

Image analyst amanda marketti Sees a resemblance.

So when I start To look deeper,

I can see that there's a tree

At the center of each feature.

Narrator: but the satellite Image shows

The pockmarked landscape covers Nearly 8 square miles.

It's simply too big To be art.

Even an artist Like manrique

Could not have created Something that fast.

It's a baffling mystery.

Narrator: low-level Drone footage reveals

The true nature Of the strange landscape.

What was thought to be A tree in each hole

Is actually a grapevine.

Despite the barren Volcanic landscape,

Lanzarote has a thriving Wine industry.

What the satellite captured

Is the world's Weirdest vineyards.

The plants here, We have first to make holes

To find the soil.

The soil is 3 or 5 meters Under the ash.

Then we make All the holes.

And we put the roots In the soil.

This ash can retain The moisture 6 months.

All that rain in winter, The plants have in summer.

Narrator: growing grapevines In a lava field

Demands extraordinary ingenuity.

Each vine is surrounded By its own protective wall.

And it's these that show up

As the bizarre C-shapes visible from the air.

They were protected From the wind

Because here is A very windy island.

The walls are made With volcanic stones.

The stones are put one-by-one.

Not as thick,

Because in the middle We have some holes,

To aid with moisture Coming to the plant.

Narrator: the c-shaped walls Not only protect the vines

But also help capture moisture To keep them watered.

But it's the love for this land That the people make,

Um, make the wine.

This is really a genius system.

I know the next time I have a glass of wine,

I'll be thinking About how much effort

Goes into Growing grapes in vines

On a tiny little Windswept island

Off the coast of africa.

Narrator: october, 2007,

A satellite image reveals

A site of massive devastation

In the canadian wilderness.

Explorer rob mark investigates.

It's incredibly remote.

The park rangers in canada Didn't even know it was there.

As an explorer, That sparked my interest.

I really wanted to find Out what this was.

And -- and -- And see it for myself.

You've got to consider That this could be

Some kind of biological attack.

Narrator: october, 2007,

Explorer rob mark investigates

A disturbing Satellite image,

Showing a swath of destruction In the canadian wilderness.

Mark: people weren't sure What it was.

The park rangers in canada

Didn't even know it was there.

Narrator: the image comes From the remote

Forests of northern Alberta, canada.

It appears that someone Or something is really

Damaging this pristine Environment beyond recognition.

When you see A huge brown patch

In the middle Of continuous forest,

You have to wonder What's going on.

Narrator: to try to solve The mystery,

Explorer rob mark sets off Into the wilderness.

The journey was Incredibly long.

The closest town is about,

And it's a small little town --

Is about 50 miles away.

You know, you have to take A boat across lake claire.

Then I started walking.

It's only 10 miles, Which doesn't sound like a lot.

I mean, that's one Of my shorter treks.

It was the toughest 10 miles of my life.

[ camera shutter clicks ]

Narrator: the sinister stain Is 3,000 feet long

By 500 feet wide.

Where there should be trees, There is nothing.

You've got to consider That this could be

Some kind of biological attack.

Are we looking at An insect infestation?

Narrator: to kill Such a huge area

Of forest would take A plague of insects

On a biblical scale.

In parts of north america,

The plague has already begun.

Bark beetles are a horrible Insect pest that are spreading

Over large areas In western north america

And killing trees For miles and miles.

Narrator: These ravenous insects

Tunnel through The trees' bark

And feed on the soft tissues,

Killing the trees Where they stand.

Since 1999, they've killed over

70,000 square miles of forest.

That's an area The size of washington state.

Narrator: but the pattern Of destruction

Doesn't look right For a beetle plague.

You would expect insects To nondiscriminately start

Attacking the forest.

But that's not The case here.

I mean, the surrounding Forest is doing fine.

Kays: when bark beetles Hit an area,

They destroy trees For miles and miles.

It can't be The bark beetles.

Narrator: explorer rob mark Continues his punishing journey

Into the canadian wilderness.

The conditions Are just horrific.

The mosquitoes are the worst I've ever encountered anywhere.

They've bit through All my clothes.

The only thing they didn't bit Through was my jacket.

Narrator: in the wilds Of central canada,

Nature rules supreme.

The foliage was so thick,

You couldn't see more Than a couple yards

In front of you.

And a lot of it was swampland.

Narrator: Studying the satellite image,

Investigators don't ignore The obvious answer

To the missing trees, Logging.

Now, this is inside Of a national park.

Right in the middle.

But of course, that doesn't Stop illegal loggers.

But felling trees, Even illegally,

Needs a lot of groundwork,

And this would be Visible from space.

Of course, loggers need To bring in big machines,

They need to bring In equipment to --

To get to a place like this.

That means roads And there are none.

Narrator: Rob mark struggles on

Towards The heart of the mystery.

Mark: it took me 3 days To go 10 miles.

And the last mile Took me 5 hours.

Narrator: When mark finally reaches The bizarre stained patch,

He's completely unprepared For what he finds.

It was just an Incredible feeling,

Because all of a sudden

The foliage opened up A little bit.

I could see the rise In the earth.

So I climbed up on it

And I saw beavers Swimming around.

It's a beaver dam, A giant beaver dam.

Narrator: this is A groundbreaking discovery.

No human has ever seen A beaver dam on this scale.

One that's so big It's visible from space.

This beaver dam is Almost 3,000 feet long.

I've never seen One this big.

In fact, it may be The largest in the world.

This is off the charts As far as size goes.

It would be 11 On a scale of one to 10.

I'm standing on top of it.

I can see a beaver lodge Out in the distance.

And as far as the eye Can see in either direction,

The dam just continued.

Narrator: At half a mile long,

This colossal dam is Too big for one beaver

To build in a lifetime.

It must be the work Of generations of beavers.

The experts looked At satellite imagery.

And they're saying that it was Being built for about 40 years.

And when you're there And you can see it,

That's not hard To believe at all.

It truly is a natural wonder.

Narrator: 1967, israel captures The golan heights,

A strategically valuable area On the syrian border.

The israeli military conducts The first aerial

Surveys of the former Syrian territory.

They see a mysterious Circular pattern on the ground.

They've discovered A place of legend.

Mizrachi: a name was given To this site,

Gilgal refaim --

The wheel of the giants.

Narrator: the golan heights On the israeli/syrian border,

After the end of The arab-israel war,

Aerial surveys spot A huge circular

Stone pattern on the ground.

Prior to its discovery,

No written record exists Of this mysterious structure.

Experts put forward A number of theories.

Altaweel: this looks to me A kind of ceremonial feature.

Did it have also Practical functions,

Such as defensive, Uh, a tower of some sort?

I don't see this As being a fortress.

I see it as being sacred space.

What is really surprising

Is the perfection Of these circles.

Narrator: the outer stone wall Stretches 508 feet across,

The size of The la dogers' stadium.

Experts are baffled As to who built

The stone circles and why.

This is not primitive People just saying,

"Let's build something Roughly that shape."

They've measured It out carefully.

And then, they've built it Using gigantic stones.

That would've been A major undertaking.

Narrator: Thousands of years ago,

People would fear passing Through this land.

According to ancient legend, It was the home of giants.

The rephaim were An ancient race of giants

Who were described In the bible.

And they were said to live In this very area,

In golan heights.

They're described As these very large,

Tall kinds of creatures.

Narrator: according to legend, The giants

Were fierce warriors With superhuman strength.

The story goes that Fallen angels

Came down onto mount hermon,

Which is next To the golan heights

And mated with human women

And produced a race of giants.

Narrator: archaeologists Name the site gilgal refaim,

The wheel of giants.

Yonathan mizrachi Has spent 3 years

Excavating the mysterious ruins.

Mizrachi: we discovered a series Of small artifacts

That were all dated To the late bronze age.

We did find some arrowheads,

Three beautiful gold earrings

And some carnelian beads

That were used As a ring, maybe.

Narrator: the layout of the site Makes mizarchi suspect

The mysterious ancient builders

Could have used this As an elaborate burial place.

Mizrachi: Looking around us,

You can see here The actual entrance

To the chamber tomb.

And from this opening, We can get into the tomb.

Narrator: But if this was a tomb,

Where are all the bodies?

We did not find Actual bones.

Narrator: it's possible The structure's builders

Used a gruesome burial tradition

Known as a sky burial.

Sky burials is a name That is given

To a very special Type of burials

In which the dead Is not buried in the ground

But is bein' exposed

For the elements Of the sky.

The bodies were places In the center of the structure.

And they waited For the vultures to come in

And to consume the bodies.

Narrator: so the site may Have been a place

For the dead to be eaten.

Gilbert: their soul, of course, Would be released

And would go to heaven,

Perhaps journeying through

The spheres Of the planets

Symbolized also by the walls Of this conce --

Concentric circular monument.

Narrator: looking again At the circular layout,

Some archaeologists disagree With the burial theory.

Instead, they see similarities With other ancient structures,

Ones that could track The passing of time.

My first reaction was, This reminds me of stonehenge.

Narrator: stonehenge In wiltshire, england

Was used As an astronomical clock

To track the arrival Of the solstice.

The wheel of giants

Is aligned to perform The same function.

The northeast gate Is due to the summer solstice.

There are two major stones

On the eastern Part of the site,

Which are marking The days of the equinox.

So we are forced to conclude

That there are relationship

Between the way This site was constructed

And astronomical bodies

That were important To those people.

Narrator: if the biblical giants Of the rephaim

Ever trod these lands,

They could've used sites like This to commune with their gods.

Often religious as well

As cultural activities Are tied in together.

So gods become associated With seasons, uh,

With times of the year, Such as the harvest or planting.

Uh, so essentially,

Accomplishing both Your ceremonial needs

Along with Your agriculture needs.

Mizrachi: it was critical To know the exact dates

Of the start Of the rainy season

And of the end Of the rainy seasons

Because these people could Prepare themselves to collect

This round of water much Like we do in our time.

Narrator: Mizrachi has discovered That the size of the stones

And the way they are Cut is different

Between the outer walls And the central mound.

This suggests they come From different times.

This could explain the two Conflicting theories

For the site's purpose.

Mizrachi: the earlier phase And early bronze age

Was used as a ceremonial center

And as a calendar.

And then 1,500 b.C. There were other people,

Nomads, that came here, Built a burial tomb.

So two distinct phases, Two different stories,

Two different cultures.

Biblical giants gave Gilgal refaim its name.

If they left any other mark Of their presence,

Archaeologists have Yet to uncover it.

The worldview ii surveillance Satellite passes

Over the southern ocean.

It captures a baffling image Of a lake on an island

6 miles off the coast Of australia.

Someone or something has turned This entire lake bright pink.

Something very strange Is going on here.

Narrator: august, 2012,

Passing high over The southern ocean,

The worldview ii Satellite captures

An image of a bright pink lake.

Something very strange Is going on here.

Narrator: the image Is of middle island,

Off the coast of Southern australia.

The bright pink patch Is a 40-acre

Body of water Called lake hillier.

I've never seen Anything like this,

A bubblegum pink lake.

The lake looks toxic.

Narrator: the pink color Could be a sign

Of deadly contaminants

Or even unknown life forms.

Investigators Scrutinize the satellite image.

Could the vivid color Just be an optical illusion?

Water can look all Sorts different colors.

Maybe that's what's Going on here.

Is it just a trick Of the light?

Narrator: when sunlight Reflects off water,

It can make it appear Shades of peach or gold.

This can also happen In satellite images,

An optical phenomenon Known as sun glint.

Sun glints occur When sunlight reflects off

The water at the same angle As a satellite viewing it.

When sunlight hits the water, The colors change.

But this is always pink.

Narrator: Examination of other images

Of the lake proves The bright pink color

Is a genuinely Strange phenomenon.

In every image, It appears pink.

This is no optical illusion.

Narrator: Aerial drone footage reveals

The lake's color Is more vivid

Than the satellite images First suggested.

The bizarre color sparks fears

The water could be contaminated.

We know that different

Pollutants will turn water Different colors.

Iron can make Rivers yellow.

Nickel can make Rivers red.

And textile factories Can actually turn them blue.

And in this case, There was a mine

Near the lake in recent history.

Could industrial pollution Be the answer?

Lake hillier May be remote

But it's not untouched.

Industry was drawn here In the past

Due to the high levels Of salt in the water.

In the lake 19th century, This lake, lake hillier,

Was subject To salt mining.

Salt was a very valuable Commodity then.

It was mined For a number of years.

Narrator: while salt mining Could discolor the water,

The lack of recent activity

Makes it seem An unlikely explanation.

The island was used For salt mining.

But that operation Closed down over a century ago.

I've never seen a salt mine have This kind of affect on a lake.

It doesn't usually Change the color

To be a brilliantly pink Almost bubblegum shade of pink.

So it's very unlikely That this has come

From a long-extinct Salt mine.

Narrator: historical records Reveal the lake's color

Is not a new phenomenon.

This lake has been pink For some time,

Even early explorers Made notes of it.

Narrator: the earliest Description of the lake

Dates back to 1802

When famous british Explorer matthew flinders

Visited the remote island.

His journal records The sighting.

In the northeastern part

Was a small lake Of a rose color.

The lake has been this color For at least 200 years.

If it predates European colonization,

It must be a natural Phenomenon of some kind.

Naturalists Consider the possibility

There's something alive In the lake

Causing The vivid pink color.

Water samples reveal Lake hillier

Has a very high salt content,

Similar to the dead sea.

This makes it deadly For most living creatures

But not all.

There is another way that You can get multicolored water.

And that is from microorganisms.

Bacteria and algae can live

In some of the most Inhospitable places on earth.

So a salty lake is par For the course.

Narrator: there is something Alive in the lake.

The life form at the center Of the mystery

Is a single-celled Microalgae

Called dunalliella salina.

Dunalliella salina produces A red pigment

That is called a carotenoid.

These are the same pigments That grow in carrots.

Here, the carotenoids Are not orange,

They're actually pink.

Narrator: The orange-red pigments

Produced by the microbes Are thought to protect them

From the sun's uv radiation.

For these weird life forms,

The highly-corrosive lake Is a comfortable home.

The microscopic creatures Are smaller than a human hair

But can still be seen From space.