All language subtitles for Secrets in the Ice S02E09 Riddle of Whale Bone Alley 1080p WEB h264-KOMPOST_track3_[eng]

[narrator]
Could a Russian lake
unknown until the 1920s

help answer one of history's
greatest geological mysteries?

Upon investigating
the lake,

a team of Italian researchers
find further anomalies.

[narrator] A mysterious sight
is discovered on a desolate
Arctic island.

As they approach the island,
they see what looks like
tall, curved posts

pointing high out of the snow.

[Dr. Anthony Cantor]
It's like stepping into
a place of great significance

that's been undisturbed
for centuries.

[narrator] New information
attempts to solve

the infamous mystery
of the sinking of the Titanic.

If this photo
is of the actual iceberg,
it confirms the size of it.

[Dr. Alison Leonard]
If the black mass
was the iceberg,

then why did they see it
higher in the sky instead of
directly on the horizon.

[narrator] These are
the strangest mysteries

trapped in the coldest places.

Lost relics...

forgotten treasures...

dark secrets...

locked in their icy tombs
for ages.

But now, as ice melts
around the world,

their stories
will finally be exposed.

The North Atlantic ocean
is well known
for its frigid seas.

Even in spring,

water temperatures
off Newfoundland
on Canada's east coast

often hover just below zero.

The North Atlantic
is ferocious.

Huge storms and towering waves
constantly threaten ships
that sail its waters.

But more than just that,

thick layers of fog
can limit visibility

while menacing icebergs
drift down
from the Arctic seas.

[narrator] Billed as
the world's
most unsinkable ship,

In April 1912,
The Titanic struck an iceberg
on her maiden voyage

sinking in less
than three hours
with 1,500 lives lost.

[Cantor] In 2002,
a previously unreleased photo
is exhibited to the world.

It's a picture of an iceberg

taken by a crew member
of a rescue ship
called the Bremen.

just days after the disaster.

There are a few photos
out there,

that experts think
might be pictures
of the iceberg

that the Titanic hit,

but this one is special.

[Anthony Morgan] The picture
matches a famous description
of this iceberg.

It's like the mirror image
of the Rock of Gibraltar.

[Leonard] This is
an amazing picture.

Part of the iceberg
is higher than the rest of it,

which makes it look a lot like
the Rock of Gibraltar.

It also shows
compelling evidence

of damage on one side.

[man] If this photo is
of the actual iceberg,

it confirms that the size
of it is at least 65 feet tall
and some 400 feet long,

and as with all icebergs,
we know that
it's far bigger underwater.

[narrator] But the photo
also reopens a mystery

that has haunted the disaster
for over 100 years.

Why didn't the crew spot
the large iceberg in time
to prevent the collision?

[Cantor] It's a clear,
frigid night with no wind.

And still they hit the iceberg
even though the sea
is completely calm.

It should've been easy
for the lookouts to spot
hazards from miles away.

Could the iceberg
have drifted further south
than they expected?

[Leonard] The captain
had received reports
of a huge ice field

in the middle
of the planned route.

So, as a precaution,
he changed course
and headed further south.

[narrator] Photos from
rescue ships The Carpathia
and The Frankfurt,

both document large icebergs
and a huge ice field
that stretched for 30 miles.

We know that icebergs
float south from Greenland

and then are pushed
down by currents

along the East Coast of Canada
towards Newfoundland.

Some last the entire journey
while others melt
a little earlier.

It depends on how big they are
and how cold the water
and the air are along the way.

[Mike MacFerrin]
Of the tens of thousands
of icebergs

that drift down
from the Arctic,

only about 1% of them
make it as far south
as Newfoundland.

So, it's strange
how many icebergs
there were that night.

[Cantor] One theory is that
that evening the moon was
at its closest to the Earth

and that proximity
can affect tidal forces.

So, maybe, those tidal forces
pushed the iceberg
further south than normal.

[narrator]
Meteorological records show
that the sun and moon

had lined up months
before to create
a rare astronomical event

known as a spring tide,

which resulted in a far
greater number of icebergs

reaching the North Atlantic
shipping lanes.

So, if the captain knew
there were more icebergs
in the area,

why were they traveling
so fast?

[Cantor] The Titanic
was traveling at her
maximum cruising speed

of 22 knots that's about
25 miles per hour.

And we know that the captain
was under orders
to make good time.

[Leonard] They thought
they had avoided the danger

of the ice fields
further north,

so they just kept going
at full speed.

[Cantor] Because the Titanic
was taller than
most cruise liners,

men in the lookout
sat 95 feet above the deck

and this allowed them
to see out 12 miles.

So this should have provided
them plenty of time

to spot the iceberg
beforehand.

[Leonard] But it's generally
accepted that the Titanic
had about one minute to react

after having spotted
the iceberg.

So, that puts them
at only half a mile away
when they see it.

It makes no sense.

[narrator] To try and
further understand exactly
what occurred

on the Titanic that night,

researchers pour over
log books of the other ships
in the area looking for clues.

Just before the accident,

a ship near by
called the Californian

actually saw the Titanic
in the distance.

The crew members
thought it looked too small
and too close to be her.

The captain of the Californian
testified that they repeatedly
signaled the ship

by Morse lamp
trying to identify them,

but the Titanic
never responded.

[MacFerrin] The Titanic
claimed she tried to signal
the Californian by Morse lamp,

but they received no response.

Why didn't they receive
each other's messages?

If you can see the ship,
you should be able to see
the flashing lamps.

[Morgan] At sea level,
the ocean can be littered
with weather anomalies.

Like low clouds
that can affect visibility.

But that night,
the visibility was great.

[narrator] If other ships
were experiencing
strange visual anomalies,

did the Titanic experience
something extraordinary

that they were completely
unaware of?

Normally, where the sky
meets the sea,

the stars are
blurred and dimmed.

This is because the humid air
distorts the contrast.

It's such a low angle

the light has to pass
through miles and miles
of atmosphere.

This interferes
with how the stars
look to us.

[Cantor]
But in testimony given

by the Titanic's
spotting officer,
Frederick Fleet,

he reported seeing
a strange clarity
in the stars

and a weird haze
like a black mass

floating above,
not at the horizon.

Fleet sees this black mass,
which also has
a strange gray peak,

a full ten minutes
before they hit the iceberg.

If the black mass
was the iceberg,

then why did they see it
higher in the sky

instead of directly
on the horizon?

[narrator]
In 2021, a photographer
on England's coast

captured this astounding
photo of a daytime mirage.

[MacFerrin] So the ship
looks like it's hovering
high in the sky

when it's actually
just floating
on the distant water.

This illusion is easier
to see during the day.

[narrator]
Could a similar phenomenon,

have been the cause
of all the confusion
that fateful night?

When they checked
the meteorological records
for the area,

they found that the water
had two radically
different readings.

[Cantor] The SS Minion,
a cable ship
that helps collect bodies,

reports in her log book,

"The Northern edge
of Gulf Stream
is well defined.

Water changed from
36 to 56 degrees Fahrenheit
in half a mile."

On this incredibly
clear night,

there was a sudden
change in temperature

where two of the Atlantic
currents meet.

[MacFerrin] The Gulf Stream
from the South usually keeps
this area warmer.

But all the icebergs
from the Labrador Current

chill the air down to freezing
from sea level to a height
of 65 yards.

But above that,

the warmer air
from the Gulf Stream
was still there.

[narrator] The conditions
were perfect

for an extremely rare
visual anomaly
called a super-refraction.

Cold air is denser
than warm air

and this causes light
to bend or refracts
before it reaches our eye

changing how far away
objects appear.

The difference in temperature
between the two ocean
currents

was radically affecting
how distant objects
were seen.

[MacFerrin] During
this phenomenon,

ships can actually appear
to be high above their actual
position on the water.

Sometimes objects
even below the horizon

like stars can get refracted
higher into the sky.

[narrator]
Could this mysterious
sub-zero phenomenon,

have caused the Titanic
to hit an iceberg?

[narrator]
After uncovering
an unpublished photo

of the iceberg
that the Titanic
struck in 1912,

researchers investigate
new information

looking for clues
as to why the crew
didn't see the iceberg

until it was too late.

A sub-zero phenomenon
known as a super-refraction
may have played a role.

At night,
this kind of mirage
can also appear

like a thin bank of haze
on the horizon.

[MacFerrin] So even though
the night was
exceptionally clear,

the Titanic's lookout,
Frederick Fleet,

noticed a black haze
on the horizon.

He claims to have seen
the iceberg

appear out of this black haze
at the last moment.

The angle and the height
of the lookout points
on the Titanic

might have given a false
impression of the distance
to the horizon.

[narrator] By the time
officer Fleet
calls the bridge

and they make
an immediate hard turn,
it's too late.

[Morgan] Ironically
and tragically,

if the ship had done nothing
and not turned,

she might not have hit
the iceberg.

[Cantor] And even if the ship
had crashed
into the iceberg head on,

it might only have breeched
the two to four
safety compartments

designed to contain
a flood and keep her afloat.

But instead,
six compartments were flooded,

which as we know
proved to be too many.

[Leonard] This sub-zero
atmospheric anomaly
at sea level

had hidden the true distance
of the iceberg
until it was too late.

[narrator]
The Titanic and her passengers
could never have known

that calm, clear night

was leading them towards
one of the great tragedies
of modern times.

Even today,

her many secrets still lie
hidden in the icy depths
of the North Atlantic.

In the Bering Sea
on the frozen edge
of the Arctic circle,

sits the remote island
of Yttygran.

Situated off Russia's
eastern most point
lies the Chukchi Peninsula.

The island is just
over eight miles long
and three miles wide

with a mountainous interior.

It's hidden under a thick
blanket of snow and ice
for most of the year.

[narrator] In 1976,
researchers stumble across
something out of the ordinary.

[Amma Wakefield]
As they approached the island
from a distance,

they see what looks like
tall, curved posts

pointing high out of the snow.

[Leonard] The landscape
in the Arctic is normally
pretty flat and barren.

So, it's highly unusual
to see anything this tall.

[narrator] Once on the island,
they discover something
they have never seen before.

Strange, curved poles
that seem to be
planted in pairs.

There's an eerie feeling
to this island.

It's like stepping
into a place
of great significance

that's been undisturbed
for centuries.

[narrator] Closer examination
of the poles

leads to a startling
discovery.

They are actually giant bones.

[narrator] The scattered
remains once formed
a long broken avenue,

roughly 1,800 feet in length.

[Jamie Clarke] There seems
to be some kind of
special geometry to the site

which is quite rare
in Siberia.

There's nothing like it
in the Arctic.

What is this place?

[Wakefield] These bones
are enormous.

What animal could
even be this big?

[Leonard] There are examples
of early humans using
gigantic mammoth bones,

to build large structures that
are somewhat similar to this,

but none of the bones
on Yttgran island
appear to be ivory tusks.

So it's highly unlikely
these are mammoth bones.

[narrator] As researchers
inspect the base
of the structures,

they uncover groupings
of giant skulls.

[Cantor] Massive bones
like this could only come
from a whale,

and upon closer inspection,
it's revealed that these are
the bones of a bowhead whale.

[narrator] The bowhead whale
lives in the Arctic,

it is considered the longest
living mammal on Earth,

with a life span of over
two hundred years.

It's distinctive triangular
head is an enormous skull,

designed to smash through
sea ice up to two feet thick.

[Wakefield] The Yttgran site
is strewn with
weathered remains

of bowhead whale skulls,

and jaw bones of
up to sixty other whales.

The 16 feet tall arches
are made of over 34 jaws.

[narrator] The avenue follows
a man-made gravel spit
along the shore.

Extending from
the center of the alley,

a stone path branches off
for 50 yards towards
rocks and the hillside.

[Leonard] This is a truly
remarkable site,

these bones just didn't
wash up on shore,

they've all been brought here,
deliberately arranged
and planted into the ground,

but why choose whale bones
to built such a place?

[Cantor] In the Arctic,
wood is very scarce,

so local people
often used animal bones
as building materials.

So these could be the bones
of beached whales,

but to find this many
seems unlikely.

[narrator] Experts believe
whale hunting has been
practiced in the Arctic,

for many centuries.

This was the result of larger
boats called,
umiaks being built.

The use of stronger harpoons
and an Arctic culture

of feeding a huge amount
of people with just one kill.

[Wakefield] The whales
can grow up to 65 feet,
and weigh 220,000 pounds.

It would've been
a highly-valued harvest.

[narrator] The whale bone
samples have been carbon dated
to the 1600s.

A time when Russian
explorers began making
contact with the indigenous
Chukchi people,

who inhabit the peninsula.

As they continue to
investigate the ruins,

researchers find several rings
made of smaller stones.

[Cantor] They look like rings,

used by the Inuit and Siberian
peoples to anchor tent skins.

And the bone formation
sticking out
of the permafrost,

may have been
substitutes for lumber,

used as posts for small huts.

[Leonard] But looking
for further evidence
of a settlement,

such as house foundations
and tools,
the dig comes up empty-handed.

It would appear that
no community ever lived here.

[Cantor] This site
shows evidence,

of having been designed
for a specific purpose,

but it doesn't have any
of the usual markers of
a significant human presence.

[narrator] When researchers
investigate a location at
the end of a smaller avenue,

they find something
remarkable.

120 conical shaped pits,

up to six feet deep
and walled by rocks.

At the bottom of these
strange pits,

they discover layers
of whale blubber
and frozen meat.

[Leonard] Permafrost stays
at a near freezing temperature
all year round.

In the Arctic,
food can be scarce,

so preserving it underground
is a great way to ensure
that one has provisions,

throughout what can be
a long and grueling winter.

[Clarke] This find
is highly unusual,

it was able to contain
tons of meat,

it's a massive amount
of storage in a place
where no one actually lived.

Could whale bone alley
be more than just a place
to store food?

[narrator] On the remote
island of Yttgran,

high in Russia's
Arctic circle,

a team of researchers
investigate a strange alley
made of bones.

An incredible
50 bowhead whale skeletons
were used in its construction.

The largest of the whale bones
weigh between 500
and 650 pounds.

It would've taken a lot of
people to carry or transport
these bones to the area.

Serious effort went
into building this site,

and that could suggest
that it was a site of
spiritual significance.

[Clarke] Other locations
around the world with strange
geometric features like,

Stonehenge for instance,
also have a tradition
of being a gathering place

for now long
forgotten ceremonies.

And they are places
where people come
from miles to feast.

[narrator] The discovery
of the hidden meat pits,

leads researchers to believe
that whale bone alley,

may have been built
to honor the whales.

[Leonard] Hunting
a bowhead whale

in a small group of umiaks,
powered only by paddles,
could be extremely dangerous.

and the hunters who did it
and provided for their
communities were revered.

But among high Arctic peoples,
so are the whales.

They believe the hunter
and the hunted are
spiritually connected.

The Chukchi performed
very specific rituals,

in order to prepare for
and perform the hunt,

and then afterwards to honor
the whale that they caught.

This included praying, singing
and feasting.

[Wakefield] We don't know
for sure but they may have
brought the whale meat,

up through the archway
and then stored them in
the pits for later use.

[Leonard] The whale bones
used to build this site
were believed to help,

the slaughtered whale's soul
return to the sea, unharmed.

[narrator] But when they
studied the meat pits,

researchers discovered
something unusual.

Carbon dating reveals that
they were created in the 1300s

This pre-dates
whale bone alley
by 300 years.

So the meat pits may have been
there before whale bone alley.

It could be that the people
wanted to pay their respect
to the whales,

and honor their importance
to their lives,

so maybe they built the site
as a kind of shrine or temple.

[Clarke]
Maybe in the beginning
whales were plentiful,

so they only needed storage
pits but if something changed
about the hunt in the area,

they may have felt
they needed to find a way,

to talk to the whales to
ensure a good harvest.

[narrator] When they compare
samples of bowhead
genetics over time,

with bones found
across the Arctic,

something strange comes up.

Their genetic diversity
has radically decreased
over the last 500 years,

which includes the time that
whale bone alley was created.

This indicates their
migration patterns
could have been altered.

[Leonard] But something called
the Little Ice Age,

may have hindered this
traditional migration,

thereby shrinking
the Chukchi's food supply.

[Cantor] The Little Ice Age
was a period
of colder temperatures,

that gripped
parts of the world
from the 1300s to the 1800s,

causing drought,
crop failures
and famine.

What this did to the bowhead
whales was reduce
their summer habitat,

where mothers would
bring their calves.

If the surface ice was
thicker they could have
had a hard time finding
breathing holes,

and just stopped coming.

So is it possible
whale bone alley was built
to bring them back?

They definitely stored meat
there but if the whales
stopped coming

it's likely the site
was abandoned for
a better hunting ground.

[narrator] Over the years
whale bone alley
stopped being used,

but the site at Yttgran island
remains an ancient pathway
to the spirit world,

frozen in time.

The Ural's are
a long and narrow
mountain range,

that runs 1,550 miles south
from the Arctic ocean,

deep into Russia.

The southern Ural's often
experience brutal winters,

that can plunge inhabitants
into a deep freeze for up to
six months of the year.

[narrator] In the winter
of 2013,

over a million people
are thrown into
a state of emergency,

when out of nowhere a massive
explosion rocks the city
of Chelyabinsk, Russia.

[explosion]

Then compelling dash cam
footage is released
that stuns the world.

It shows an object
speeding across the sky,
glowing brighter than the sun.

[Dr. Kim Tait] Locals discover
a giant hole in the ice,
covering lake Chebarkul.

When they dive the lake,
they find a huge metallic rock
sunk in the bottom.

It's over five feet long,

three feet wide and weighs
an astounding 1,300 pounds.

[narrator] It's one of
the largest meteor fragments

ever recovered
in modern history.

Scientists studying the meteor
discover its unique striations
and ancient scars

tell an epic tale.

This meteor has been bouncing
around the universe

for over four billion years.

Could this incident
help shed light
on one of the most mysterious

meteor events
in modern history?

[narrator] When a meteor
crashes to Earth

near the Russian city
of Chelyabinsk in 2013,

researchers wonder
if it could help solve
another mysterious event

that occurred more than
100 years earlier.

In the year 1908,
in Central Siberia,

farmers near the remote
Tunguska River,

hear an intense
crackling sound in the sky.

They look up to see
a bluish pipe-shaped object

moving across the sky.

A series of blasts
that sound like cannon fire

echoes across the landscape.

[Leonard] Then
a massive explosion blows
the farmers off their feet,

slamming them to the ground.

What could have caused
such a devastating concussion,

as well as that fire
in the sky?

[narrator] Since 2013,

researchers have discovered
17 deep holes

in the Siberian permafrost
they cannot explain.

[Cantor] They don't know
how they form.

And because the area
is so remote,

they've never actually
witnessed one forming
in real time.

[narrator] Two-thirds
of Siberia is permafrost

and permafrost
is a natural reservoir
of methane.

Could the Tunguska event
be a rare
geological explosion?

[narrator] A phenomenon
caused in part
by massive methane build-ups

under the permafrost
have resulted in explosions,

leaving large craters
pocketing the tundra.

But no such methane explosion
has ever been witnessed.

Nor have there been reports
of any loud explosions
in the area.

[Wakefield]
It's not until 1927,

19 years after the explosion

that Russian mineralogist
Leonid Kulik

decides that someone needs to
conduct an investigation.

After interviewing locals,

Kulik focuses on finding
the epicenter.

He climbs a ridge
and observes toppled trees,

as far as the eye can see.

[narrator] The trees
aren't bent over.

They're snapped off
by a very powerful force.

This indicates that the blast
must have come
from a central location.

[Tait] The blowdown
is so massive

he is unable to estimate
just how much forest
is destroyed.

[Wakefield] But when he
arrives at the epicenter,
he is mystified.

There is no impact crater.

[narrator] The epicenter
of the blast contains
upright trees,

but with their branches
stripped and burnt.

Kulik even drains some marshes
which he suspects might be
impact craters,

made by smaller
meteor fragments.

But he finds nothing.

[narrator] Modern researchers
now know that

80 million trees
were flattened in a strange
butterfly-like pattern.

They estimate
the explosion was
roughly forty times larger

then the 2013
Chelyabinsk meteor

that leveled over
830 square miles of forest.

[Cantor]
Is there something else

that could have destroyed
a massive wilderness
like this?

[narrator] Largely made
of dust and ice,

comets travel through
the frozen void of other space

at thousands of miles
per hour.

But they burn up
in a very dramatic fashion
and then explode.

As they enter
the Earth's atmosphere,

temperatures of comets
can reach an astounding
3,000 degrees Fahrenheit.

[Tait] If Tunguska
was a comet,

the ice could have been
vaporized and released
into the upper atmosphere.

Maybe that's why
there is no obvious crater.

Days after the explosion,
before anyone knew
what happened,

skies all over Europe

were filled with
a strange luminescence.

London's newspapers reported

that it was bright enough
to play tennis at midnight.

Maybe the additional ice
in the atmosphere
reflected light from the sun

down on to Europe
and created a sort of
glow effect that night.

[narrator] But the comet
theory only supports
the lack of an impact crater.

A large object made of ice
would have entered
the atmosphere,

then exploded and vanished
almost immediately.

It couldn't have travelled
as long,

nor as far across the sky
as was reported.

[Wakefield] There also
would not have been a light
brighter than the sun.

Nor would there have been
a sequence
of smaller explosions.

[Leonard] Scientists
have found meteor fragments

frozen in peat bogs
and even embedded in trees.

But there is no way to tell
whether or not

the fragments are from
some smaller
or more ancient meteor.

[narrator] Then in the 1990s,

Italian researchers noticed
something strange
on an old map.

[Cantor] A body of water
called Lake Cheko,

just four miles
from the epicenter
of the Tunguska blast,

does not exists on any map
prior to 1928.

[Wakefield] It is
a remote location

and maybe not
all the lakes were mapped.

But it is still very strange.

[narrator] Could this
previously unknown lake
be a flooded impact crater

created by
the Tunguska explosion?

[narrator] In a remote
Russian wilderness,

researchers investigate
a strange lake that didn't
exist on any map before 1928.

Could the bottom of this lake
hold clues to the mysterious
Tunguska explosion of 1908?

Upon investigating the lake,
a team of Italian researchers
find further anomalies.

Echo soundings reveal
it has a rare conical bottom,

rather than the flat bottoms
of the other lakes
in the area.

[Wakefield] And they discover
what they think
are half-buried tree trunks,

submerged at the bottom
of the lake.

[narrator] Is Lake Cheko
evidence

of the missing impact crater
made by the Tunguska meteor?

Unfortunately,
researchers have not

been granted additional access

to the bottom of the lake.

Limiting their ability
to find new evidence
to support their theory.

[narrator] But in 2020,

a new team of researchers
claim that they have made
a breakthrough.

By studying the more recent
2013 Chelyabinsk meteor

recovered from a frozen lake
in the Urals

[Tait] They realize
new data about the meteor

gives them the ability
to simulate

what happens
when a very large meteor,

made of iron, hits the Earth.

[narrator] Based on
cutting edge
computer simulations,

they concluded
that the Tunguska meteor

was the size
of a football stadium

and weighed 220 million pounds
when it entered
Earth's atmosphere.

It travelled across the sky
at a speed of
30,000 miles per hour.

[Cantor] Temperatures
on the comet

would have been about
3,000 degrees Fahrenheit

as it entered
the Earth's atmosphere.

And if a meteor of that size

had hit the Earth
at that speed,

the impact crater
would have been
about 2 miles wide.

[Wakefield] It could have
plunged the entire planet
into turmoil.

Thrusting up tons of debris
that would have shrouded
the Earth.

Causing millions of deaths
and devastating
Earth's wildlife.

It had the potential
to trigger another ice age
almost overnight.

[narrator] But if
the Tunguska meteor
did crash to Earth,

why wasn't the planet
thrown into chaos?

[Cantor] Experts believe
something incredible happened

that gave life on Earth
a second chance.

Our atmosphere
is made of gases.

And when a meteor enters
the atmosphere,

these gases
act like a protective shield.

[narrator] The scientists
suggest that
the Tunguska meteor

encountered a monumental
amount of friction

and push-back
from Earth's atmosphere.

This then caused it
to change course

veering into
and through the stratosphere,

and back out into space.

Traces of this immense
explosion

would be hard to detect
on the ground.

'Cause this type of asteroid
is made up of
sulfur compounds,

which are readily found
on Earth.

[narrator] But a near miss
could still hold

dark implications
for humanity.

[Cantor] Once inside
our solar system,

meteors are usually drawn
to the sun

by its immense
gravitational force.

They then start
orbiting the sun
until they hit something.

Could that something,
one day, be the Earth?

[Wakefield] The good news is,
our atmosphere protects us
from certain sizes of meteors.

The bad news is,
the Tunguska meteor...

may still be out there,
and it could possibly
return in the future.

[narrator] The Pacific Ocean,
the largest ocean on Earth,

at over 14,000 feet deep,

its frigid waters are one
of the Earth's last
unexplored frontiers.

[Clarke] It's so huge,
it's like another world.

Only about 20%
of the Pacific floor
has even been mapped.

There's still so much
we don't know

about what's down there.

[narrator] In 1997,
researchers looking
for underwater volcanoes,

hear a strange sound,
on their hydrophones,

over 1,500 miles,
off the coast of Chile.

[Tait] The sound went
on for almost a minute.

It sounded like
a low frequency,
underwater roar.

[Morgan] This sound
was louder than
a rocket launch.

It's the loudest sound
we've ever recorded
underwater.

[narrator] The ocean
is filled with constant
sounds of creatures,
geology, and ships.

And experts know
their sound signatures.

But, they had never
heard anything
like this before.

[Morgan] They replayed
the sound over and over,

trying to figure out
what it could be,

and finally, when they
sped it up 16 times,

it sounded like
"bloop".

I mean, what is that?

[mysterious sound playing]

[narrator] Hydrophones
are special microphones,

used to detect
sound underwater.

Sound waves travel
over four times faster
in water,

and hydrophones
are designed to pick up
sound waves

that move through
the unique high pressure
of underwater atmospheres.

By playing sounds
at different speeds,

experts can often gain
valuable clues
as to their origins.

[mysterious sound playing]

[narrator] But, initial
investigations into the sound,
have researchers baffled.

The first hydrophone
network was called SOSUS,

short for the sound
surveillance system.

It was built
by U.S. scientists,

to act as surveillance
microphones during
the cold war.

[narrator] During the 1960s,

the U.S. navy had placed
a number of listening devices
around the Pacific,

as a new form of defense,
hoping to hear
enemy submarines,

before they
could spot them.

But, by the time,
they recorded this bloop
sound decades later,

they had a network
of scientific hydrophones
across the Pacific,

some up to 2,000 miles away
that also picked up
the strange sound.

For the sound to travel
that far, whatever made it,
had to be huge.

[narrator] In 1997,
researchers studying
underwater volcanic activity,

picked up a strange sound
on their hydrophones.

over 1,500 miles,
off the coast of Chile.

They searched for,
not just where the sound
came from,

but what
the sound came from.

A lot of the sounds,
in the ocean is made
by machines.

So it's possible
that the sound could
be man-made.

Maybe from a large ship,
or a plane, or even a rocket
crashing into the water.

[narrator] The ocean
is made up of layers
of water,

of different temperature,
and salinity.

Sound waves travel faster
in warm, salt water,
and under high pressure.

One layer, the worlds
oceans, known as
the deep sound channel,

contains prime conditions.

It's located between
300 to 1,000 yards
below the surface.

Sound waves can travel
through this layer
for thousands of miles.

The deep sound channel
is an excellent conductor for
low frequency sound waves,

which is why the researchers
put the hydrophones there,
in the first place.

[MacFerrin] But, even
in perfect conditions
like this,

noises from ships
and other man-made objects,

wouldn't be able to travel
across 2,000 miles.

[Tait] And these man-made
sounds tend to occur closer
to the ocean surface,

and therefore, generally
travel in the upper layers
of the ocean,

while the sound of the bloop
was recorded considerably
deeper in the Pacific.

[narrator] Because
hydrophones had
originally been set up

to detect enemy submarines,
researchers wonder

have they now detected
a new top secret
military technology.

The scientists
reach out to U.S. Navy
intelligence officers,

to see if they can
identify the sound,

or maybe shed light
on any new technology that
was being used in the oceans.

But, they deny any knowledge
of potential operations,
that could've caused it.

[narrator] Researchers
of the National Oceanic and
Atmospheric Administration,

or NOAA,

analyzed the visual
representation of the
bloops audio frequency,

and then compared it
to other marine sounds
that have been identified,

to see if they
can find a match.

But, when they look
at the spectrograms,
side by side,

the bloop appears to resemble
sounds made by marine
mammals underwater.

But, what animal
would be large enough
to create such a loud sound?

[narrator] The Blue Whale
is the biggest mammal
to have ever lived.

They can grow
up to 100 feet long,

and their calls
can reach 188 decibels.

That is loud enough
to burst a human eardrum,

and their calls have
been heard and recorded
from hundreds of miles away.

[Clarke] But, the bloopers
recorded by hydrophones that
were thousands of miles apart.

By using Blue Whale
sound production dimensions,

researchers discovered, for an
animal to make a sound that
could travel that distance,

the creature would
have to have been
over 250 feet long.

If the sound was made
by an animal, it was something
bigger than a Blue Whale.

[narrator] Each year,
new deep sea creatures
are being discovered,

and the researchers wonder,
was the bloop made by an
undiscovered marine species?

It's entirely possible.
We're learning more about
new marine life all the time.

For example, there
are only a few giant squid,

that have ever been seen
reaching 60 feet in length.

[narrator] But, without
any more evidence,

the researchers
start to consider
supernatural theories.

[Morgan] They wonder
if they have discovered
the legendary kraken

or the colossal Megalodon.

[MacFerrin] Finding something
like that would be amazing.

It's every scientist's dream.

But, there's really
no evidence to support
these wild theories.

But, if it wasn't
the mysterious creature,
then what could it be?

[narrator] In 2010,

scientists doing
an acoustical survey
in waters near the South pole,

take another look
at the source
of the mysterious bloop.

NOAA researchers
reanalyze the hydrophone data,

and are able
to triangulate the bloops
origin, to Antarctica.

[Clarke] Researchers
from the Pacific Marine
Environmental laboratory

have been recording
underwater sounds regularly
in Antarctica since 2005.

So, now there's a new, huge
database of sounds, they can
use to compare with the bloop.

When they slow the bloop
down to real-time speed,

researchers feel like,
maybe we've got a match here.

[narrator] In the Southern
ocean, the main source of
underwater sound, is ice.

crashing, breaking up,
and collapsing from
the huge ice shelves

and glaciers,
that surround Antarctica.

We now know that there's tens
of thousands of these ice
quakes that happen every year.

They didn't know
this when the bloop
was first recorded.

And, when they're played
in real-time, not sped up,

these icy audio signals
appear very similar,
to the bloop.

[narrator] The bloop was most
likely created, somewhere
between the Bransfield Strait,

and the Ross Sea.

At the right frequency,
and perhaps along the deep
sound channel in the Pacific,

the bloop travelled
thousands of miles,
and was just by fluke,

recorded for the first time.

[Morgan] So, scientists
think that this bloop sound
was actually,

thousands of gigatons of ice,
crashing explosively,
into the sea,

but sped up 16 times,
that enormous,
thunderous roar,

sounds just like
a big drop of water.