All language subtitles for Historys.Greatest.Mysteries.S04E01.The.Loch.Ness.Monster.1080p.HULU.WEB-DL.AAC2.0.H264-WhiteHat_track3_[eng].1

Tonight, the world's
most enduring

deep-sea monster mystery.

I saw the head,
the neck, and the huge body

which I'd say was about
30 feet long.

HEIDI HOLLIS: We are talking
about thousands of sightings,

and that's a conservative
estimate.

It could be tens of thousands
over the course of 1,500 years.

Despite so many sightings,
the beast remains unidentified.

There are millions of species

that we haven't found
or classified yet.

There's stuff out there that
we don't know anything about.

As far as we can tell,

nobody has ever captured
a Loch Ness Monster.

Now, we'll explore
the top theories

surrounding
this elusive creature.

Hey, maybe it's a plesiosaur.

KRISTYN PLANCARTE: What about
the thing that washed up

in Stronsay, or the similar
lake monster in Sweden?

JONATHAN BIRD: There are tons
of eels in Loch Ness.

Is it possible that
there is a gigantic eel?

DUSTIN GROWICK: Many people
still believe it's real.

Does the Loch Ness Monster
exist?

And if so, what is it?

[music]

LAURENCE: Northern Scotland,
August, 564 A.D.

According to legend,
an Irish monk named Columba

is attempting to cross
the River Ness with a group

when they stumble upon two men
burying a friend.

This man had just been swimming
when he was attacked

by an enormous water beast.

DUSTIN: You would think
that after that exchange

the monks would try to find
a different river crossing.

But Columba stays, undeterred.

Maybe he didn't believe
the locals,

or he just thought
that his faith will protect him.

ZAK MARTELLUCCI:
He orders another monk

to swim across and retrieve
a small boat.

As this monk
gets about halfway across,

this creature suddenly appears
out of the water,

gives a giant,
bellowing roar.

LAURENCE: Everyone panics,
with the exception of Columba.

He steps right up
to the edge of the bank,

makes the sign of the cross,
and demands the monster

leave the man alone.

LAURENCE: The creature
supposedly obeys.

To the witnesses on shore,

it is nothing short
of a miracle.

KAREN: Columba eventually
achieves sainthood,

and this tale
is supporting evidence

for his faith and abilities.

And this story is retold
for years to come.

LAURENCE: Debate continues
for centuries.

What could this
mysterious creature actually be?

In Columba's time,
and continuing

for several centuries after,
through the Middle Ages,

dragons are still believed
to be real.

And so, many people think
this is some sort of sea dragon.

But nobody has any concrete
evidence of what it is,

or if it even truly exists.

It remains
an essentially local legend

for quite some time.

LAURENCE: Then,
in the 20th century,

new visitors flock
to the Highlands,

thanks to one
remarkable invention--

the automobile.

By the early 1930s,
there's a road built

along the shore of Loch Ness.

HEIDI: One afternoon in 1931,

a local couple
were driving along there

when they spotted
a large animal.

It was rolling and plunging
on the surface of Loch Ness.

Immediately they report
their experience

to the local papers.

When published, their story

uses the now-famous
key word, "monster."

LAURENCE:
The Loch Ness Monster--

a name that soon spreads
far and wide.

HEIDI: Now all of a sudden,

the tourists are not coming

to see the beautiful lake
and the rolling hills.

They are coming
to see the monster,

who is soon lovingly called
"Nessie."

And guess what?
They are spotting it, all right.

They are spotting it in droves.

LAURENCE: Soon, there are more
eyewitness accounts of Nessie,

and they seem convincing.

I saw a-- a large object.

It came right out of the water
in front of me.

I was wading in the river
fishing with-- fly-fishing.

The best view I ever had
was the very first in 1934.

I saw the head, the neck,
and the huge body

which I'd say
was about 30 feet long.

LAURENCE: Each new glimpse
brings fresh seekers,

all with the latest technology.

ZAK: We shouldn't
have to wait long

before somebody
captures it on film,

and then we're bound
to know what it is.

LAURENCE: In April of 1934,
that finally happens,

and it becomes
front page news.

A gynecologist from London
named Robert Kenneth Wilson

went on a fishing trip
over there to Northern Scotland

when he decided to go
for a walk.

During his stroll,
that's when he spotted something

unusual in the water.

Luckily, he had his camera,
and he snapped a picture.

And there we have it,

probably the first photograph
of Nessie.

LAURENCE: Known as
"the surgeon's photo,"

the image causes quite a stir.

KAREN:
Shows a silhouetted creature

with a long, slender neck,
a small head,

and a large body emerging
slightly above the waterline.

DUSTIN: This is amazing.

We finally have some
visual evidence

to back up these
eyewitness accounts.

And not only that, some experts

think they can identify
this animal.

LAURENCE: The creature's shape
also strikes a chord

with British paleontologists.

So, what particular species
do you think it is?

The evidence as I interpret it
all fits--

and I know this is
a fantastic statement--

but this all fits plesiosaur.

LAURENCE: Plesiosaurs
are a marine reptile

dating back millions of years.

Their fossils were first
discovered in 1823

during a dig in England.

HEIDI: Fossil hunter Mary Anning
actually uncovered

a nearly complete skeleton
of a previously unknown species.

It is given the name
Plesiosaurus,

meaning "near to reptile."

Plesiosaur fossils have been
found around the world,

but a major cluster of them
comes from here in Scotland.

We're talking about hundreds
of specimens.

This was, at least at one time,
this creature's main habitat.

KAREN: These fossils show
that the plesiosaur

was an enormous
water-dwelling creature,

over 20 feet long.

They had broad, flat bodies
with short tails.

Their limbs had evolved
into four long flippers

that propelled them through
the water in a flying motion.

HEIDI: They breathe air,
and so they would constantly

have to come to the surface
for oxygen.

Most notably,
they had long thin necks.

The surgeon's photograph
happens to fit that to a T.

And coincidentally, so do most
of the witness statements.

LAURENCE: Though some believe
Nessie could be a plesiosaur,

the theory has one major flaw.

DUSTIN: Scientists believe
that a mass extinction event

about 65 and a half
million years ago

killed about 75% of all
species on Earth,

including dinosaurs
and plesiosaurs.

A plesiosaur should not be
inhabiting these waters today,

in Saint Columba's time,

or any time
during human existence.

They're supposed
to be extinct.

LAURENCE: But is it possible
the plesiosaur somehow survived?

When we say that 75%
of the creatures

did not survive the last
mass extinction event,

that means that 25% did survive.

So, platypuses,
turtles, crocodiles--

all kinds of animals
actually did survive that event.

LAURENCE:
Scientists point to a fish

long thought to be extinct
as an example--

the coelacanth,
discovered alive in 1938

in South Africa.

KAREN: The entire
scientific community believes

that the coelacanth dies off
66 million years ago.

There are no fossils after that.

It's the same time
as the plesiosaur.

If the coelacanth can still be
swimming around out there,

what's to say that
a small number of plesiosaurs

couldn't have somehow
avoided extinction, too?

LAURENCE: But to many,
the plesiosaur theory

remains too far-fetched.

DUSTIN: The fact
that they breathe air

could account for the animal
being sighted at the surface,

but I actually think
that's evidence

against Nessie
being a plesiosaur,

'cause it would have
to surface all the time.

If that were the case, we'd have
so many more photos and videos.

One would have probably
already been caught

and put in a zoo by now.

Plus a creature as big
as a 20-foot-long plesiosaurus

would need a lot of food
to sustain itself.

ZAK: There's just not enough
of a food source

for a massive beast,
let alone a community of them,

which there would have to be
in order for this species

to survive this long.

HEIDI: And honestly,
the plesiosaur theory

only hangs on the one
photograph.

And before the surgeon's photo
is published,

absolutely nobody
thinks it's a plesiosaur.

LAURENE: 1934-- the first photo

of the supposed
Loch Ness Monster

incites public frenzy
and a torrent of tourists

looking for Nessie.

But not everyone
believes the image

known as "the surgeon's photo"
is authentic.

DUSTIN: Dr. R. Kenneth Wilson,
who submits this photo

to the Daily Mail,
claims that it's real,

but others say "Hold on, this is
an elephant's trunk

"rising out of the water,
or maybe it's a dolphin's fin,

or something else."

KAREN: What we do know is that
the photo that's published

is substantially cropped
and zoomed in,

which blurs the shape
of the creature a bit

and skews any sense of scale
or perspective.

But when some experts
go back and examine

the original, uncropped photo,

they see something
entirely different.

Seeing the uncropped version

changes their perspective
completely.

They believe that whatever
this beast is in the water

isn't anywhere near
20 feet long.

It's maybe three feet long,
at the most.

LAURENCE: Is it possible that
the most famous photo of Nessie

is somehow doctored?

HEIDI: People question
the authenticity

the moment this photo
comes out in 1934.

But many people still believe
this thing is real.

And there is
no definitive proof otherwise.

Then, in 1994,
the photo's whole provenance

comes into question,
thanks to a deathbed confession

by a man named
Christian Spurling.

He claims that in 1933,
his stepfather was hired

by the Daily Mail
to find evidence

of the Loch Ness Monster.

Spurling is the stepson
of a big-game hunter

and filmmaker named
Marmaduke "Duke" Wetherell.

KAREN: So, Duke goes on
this expedition to Scotland,

and it doesn't take him long
to find

these really large animal tracks
near the banks of the loch.

Judging from the size
of the footprints,

Duke estimates the animal
to be at least 20 feet long.

LAURENCE: Wetherell sends
plaster casts of the tracks

to a London museum.

When the results came back,
they find that the tracks

didn't come from a monster,
but they came from a hippo.

It sounds unusual
because we all know

that hippos do not come
from that area.

But back then, hippo's feet
were used as umbrella holders

and ashtrays,
so it wasn't that uncommon.

DUSTIN: So, one of two things
is happening here.

Either Duke faked the tracks,
or someone was fooling him.

The Daily Mail is not happy
about either of these options,

so the paper
publicly ridicules him.

LAURENCE: According
to Spurling's confession,

Wetherell concocts a scheme
to save his reputation.

Duke goes to his stepson,
who happens to be a model-maker,

and asks him
to fabricate something

that looks like the eyewitness
descriptions of the beast.

So, using plastic, wood,
and a toy submarine,

they create this model
of a creature

with a long neck
and small head.

HEIDI: And then, Duke goes
to the loch with his other son

and creates
that iconic photograph.

But in reality, it's just
a picture of the model

floating in the water.

LAURENCE:
Now, Wetherell just needs a way

to make the photo public.

The perfect solution?

The surgeon,
Dr. R. Kenneth Wilson.

Duke realizes the best way
he can pull this off

is if he finds
someone trustworthy

who can claim the photo
as their own.

So, he passes
the photo on to Wilson,

the very same surgeon who
publicizes the infamous photo.

HEIDI: The surgeon's photo
is really a game-changer.

It unleashes
a torrent of tourism

that still is going on
to this day.

LAURENCE: Over the years, there
are more fake photos of Nessie,

all of them
eventually debunked.

Then, in 2016, there's suddenly
new evidence

that suggests
the monster could be real.

DUSTIN: Researchers
from Kongsberg Maritime

send an underwater drone
deep into the loch

to search for any evidence
of the monster.

And surprisingly,
the sonar returns images

of something that has the shape
of the monster's head and neck.

At first, this is big news.

LAURENCE: Until it's determined
to be a prop from a movie.

DUSTIN: In 1969,
a Sherlock Holmes movie

was shot at the loch.

In the movie, there's a scene
where the Loch Ness Monster

attacks the heroes.

But during the filming,
director Billy Wilder

takes a look at the monster prop

and decides he does not like
the humps on the back.

So, they remove the humps,
and accidentally cause the prop

to sink to the bottom
of the loch.

HEIDI: There's a lot of fakery

surrounding
the Loch Ness Monster.

People love getting their
15 minutes of fame from this.

Every Nessie sighting
gets attention,

and people
love getting attention.

LAURENCE: But the sheer volume
of sightings throughout time

convince many
that Nessie is real.

We are talking about thousands
of sightings,

and that's
a conservative estimate.

It could be tens of thousands,
over the course of 1,500 years.

DUSTIN: Before cameras,
before Photoshop,

before robotic toy submarines.

Sure, a few dozen sightings
may be fake.

But all of them?

[clicks tongue]
No way.

LAURENCE: A key piece
of evidence for believers--

a discovery in 1808 on
the Scottish island of Stronsay,

just 120 miles from Loch Ness.

According to eyewitnesses,
the corpse of a strange animal

washes up on the beach
and a crowd gathers to see it.

It's the rotting carcass
of an enormous,

unidentified sea beast,
and the locals

have never seen
anything like this.

Eyewitnesses call it
the "Stronsay Beast,"

and describe it as having
a serpentine-like body

with a long neck and six limbs
that resemble paws.

They say its head is small
like a sheep's,

and its eyes are similar
to a seal's, but bigger.

It has some short hairs
around its head and neck,

and skin that is rough
to the touch

and grayish in color.

ZAK: The measurements they take
show how gigantic

this thing actually is.

It's 55 feet long,
with its neck alone

measuring 10 feet.

LAURENCE: Authorities
document the creature

and take sworn
witness statements.

This is the early 19th century,
so they can't photograph it.

But they also know the story
won't be believed,

so they need
to prove it somehow.

So, they bring
all the eyewitnesses

to the capital where they can
swear before a magistrate

that what they saw
is the truth.

We still have these records,

along with drawings
that they made.

KAREN: The carcass
is quickly decomposing,

and they lack
the right equipment to transport

or preserve this massive animal,

but they do take samples
of the specimen.

The skull is saved
and sent to London

for further examination,
but unfortunately,

it is destroyed during
the Blitz of World War II.

The vertebrae,
on the other hand,

are sent to leading anatomist
John Barclay

from Edinburgh's most successful
school of anatomy.

He concludes that this
is unlike any other creature

he's ever seen, opening the door
to the possibility

that this is
a newfound species.

HEIDI: The connection
isn't initially made

to the Loch Ness Monster,
because it's not the 1930s yet,

so Nessie fever
has not swept the nation.

The legendary creature
is not famous yet.

But once it becomes famous,
theorists realize,

"Hold on,
this might be the same animal."

LAURENCE: The fact that Stronsay
is just 120 miles from Loch Ness

earns extra attention.

And the physical description
of the two creatures

is strikingly similar.

Gray skin, long neck,

some kind of flipper-like
appendages, small head.

The only real major difference
I would say is the size.

The Stronsay Beast
according to those eyewitnesses

is much larger than anyone
has ever claimed

the Loch Ness Monster to be--
nearly twice the size.

That doesn't necessarily rule
out the same species though.

Perhaps Nessie
is just smaller.

DUSTIN: Or, there's an even
more compelling idea.

What if the creature
in Loch Ness

is a younger specimen?

What if the loch is where
these animals breed?

It certainly happens.

Salmon swim in
all the way from the North Sea

and breed in the River Ness
and the loch.

It's an annual event.

LAURENCE: This may also explain
the inconsistency of sightings.

ZAK: If that's the case,
the animal breeds

and raises its young
in the loch,

but then it migrates
out into the sea.

So, the reason people
don't see it all that often

is because it doesn't live
in Loch Ness full time.

KRISTYN: It's possible.

Loch Ness and Stronsay
are actually connected by water.

Both the Caledonian Canal
and the River Ness

connect the loch
to Rosemarkie Bay,

and ultimately the North Sea.

So, it's entirely possible
that whatever washed up

on the Isle of Stronsay
is the same species

as the Loch Ness Monster.

LAURENCE:
If the Loch Ness Monster exists,

the waters it lives in
remain largely unexplored.

But as marine science evolves,

new theories emerge
about what Nessie might be.

Over time, modern technology
has allowed scientists

to dive deeper into bodies
of water than ever before.

And the diversity of life there
is amazing.

ZAK: And the more species
we discover,

the more we have to compare
to the Loch Ness Monster

to see if they're a match.

LAURENCE: And that approach
has yielded

one particularly
compelling candidate.

In 2012, biologist Jeremy Wade
publicizes a theory

that some scientists
have held for years

on the origins
of the Loch Ness legend.

Nessie may in fact be a creature
that scientists already know--

a highly-elusive,
very mysterious species,

but one that is very real.

The Greenland shark.

DUSTIN: Why a Greenland shark?

Why this animal
in particular?

Upon first blush,
this theory seems way out there.

For decades
Nessie has been described

as more of a dinosaur-like
creature.

But that belief
stems from a photo

that we now know to be a hoax.

LAURENCE: What if Nessie is not
the long-necked beast

in the surgeon's photo,
but something else entirely?

KRISTYN: Like Nessie,
Greenland sharks are elusive.

They tend to prefer very deep,
very cold water.

That makes them hard to study.

They are rarely
photographed or filmed.

A lot of what we know about them
has only come to light

in the past couple of decades,

despite the fact
that our best guess

is they've roamed the Earth
for over 100 million years.

DUSTIN: In fact, the first time
one was photographed

wasn't until 1995.

And when you first look at it,

you may not initially
see Nessie, but keep looking,

and think about some
of the eyewitness accounts.

It could fit.

LAURENCE: Greenland sharks
are typically mottled gray

or brown-- the same colors used

to describe
the Loch Ness Monster.

And they're big.

Greenland sharks can get
to like 20 feet long

and like four tons.

So, they're very,
very large animals.

They can actually be larger
than great whites.

LAURENCE: Unlike most sharks,
they have a small dorsal fin.

ZAK: If a normal shark were
cruising along the surface

of Loch Ness,
people would know it,

it's instantly recognizable.

But the odd, stubby fin
of the Greenland shark

could easily be mistaken
for something else--

possibly the head or a hump
of some kind of sea monster.

DUSTIN: Which definitely applies
to most sightings of Nessie.

Witnesses often describe
multiple humps

undulating through the water.

When you think back to the time
of Saint Columba,

through the Middle Ages,
and the Nessie sightings

even up to the 1800s,
there are still people around

who believe in things
like mermaids

and all kinds
of fantastical creatures.

So, it's not surprising that
somebody could catch a glimpse

of a bizarre-looking shark
like this and think

that it is a monster
in Loch Ness or the River Ness.

I mean, it kind of does look
like a monster.

LAURENCE:
According to some scientists,

Greenland sharks also move
like the Loch Ness Monster.

So, most people imagine sharks
as being fast agile hunters.

You think of like
a great white or a mako shark

chasing down a meal.

Nessie sightings tend to
describe a slow-moving animal.

JONATHAN: Greenland sharks live

in a completely
different habitat

where the water's really cold,

and they have a very slow
metabolism.

So, they swim slowly,
they eat slowly.

They do everything slowly.

DUSTIN: That is why they're
sometimes called sleeper sharks.

If an enormous
Greenland shark surfaced

and moved along the water
of Loch Ness that slowly,

it's easy to see how it could
be misconstrued

as something
other than a shark.

ZAK: And why don't we see
Nessie very often?

Because a shark
doesn't have to come up for air.

It may occasionally make
its way to the shallows,

but not very often.

These Greenlands
love the depths.

KRISTYN: The problem with
the Greenland shark theory

is that Loch Ness
is a body of fresh water.

For a long time we've thought
that Greenland sharks

are saltwater creatures.

LAURENCE: But new evidence
suggests otherwise.

Greenland sharks have recently
been filmed

in Canada's
St. Lawrence River.

KRISTYN: In fact, they go all up
and down the St. Lawrence Seaway

through America and Canada,
and that is entirely freshwater.

LAURENCE: A similar
freshwater route

connects Loch Ness
with the North Sea.

DUSTIN: If Greenland sharks can
live in both freshwater

and seawater,
it's entirely possible

one could survive in Loch Ness,

or at least migrate in
from time to time.

ZAK: Maybe there's even a chance
that the Stronsay Beast remains

were misinterpreted, and it was
some kind of large shark

that was capable
of going back and forth

between the sea
and the loch.

All of this evidence excites
the scientific community.

There are so many similarities
between Greenland sharks

and Nessie, experts think
that they've solved the mystery.

LAURENCE: A 2016 experiment
at the University of Copenhagen

only adds to that excitement.

These scientists
take 28 Greenland sharks,

and have them radiocarbon dated
to determine their age.

Shockingly, one of them
is over 400 years old.

ZAK: 400 years makes
the Greenland shark

the world's longest
living vertebrate.

To give you an idea
of how incredibly old this is,

there could be a shark swimming
out there that was alive

before the Pilgrims
left England on the Mayflower.

The team also finds
that these sharks

only grow about
a centimeter every year,

and they don't even reach
sexual maturity

until they are
about 150 years old.

ZAK: For some,
this seals the deal

that the Loch Ness Monster
is a Greenland shark.

That longevity
could be key

to how isolated
the sightings have been.

Nessie seems to be
a solitary creature.

No one has ever seen
two at once.

Most animals, you would need
a family of them

living in the loch
and regularly breeding

to account for so many years
of regular sightings.

One single Greenland shark
could be responsible

for all of the sightings
dating back to the 1600s.

LAURENCE: To find out
if a Greenland shark

is living in Loch Ness,

a team looks for proof in 2017.

A team of scientists
led by Dr. Neil Gemmell

from the University of Otago
in New Zealand

did a really interesting study.

They went to Loch Ness
and they took water samples

all over the lake-- the middle,

the sides,
the ends, everywhere.

From a half a liter of water,

we can get a very,
very good catalogue

of life within the loch.

JONATHAN: They did
a DNA analysis of all the DNA

that they found in that water.

So, in theory,
any living creature

that has been in that water
would leave a DNA trace.

ZAK: If there's a shark
in there, they'll know,

along with anything else
that might be swimming around.

LAURENCE: After two years,
on September 5th, 2019,

they announce their results.

First and foremost,
they found no evidence

of Jurassic-era animals,
including plesiosaurs.

ZAK: But more importantly,
they found no evidence

of shark DNA,
including Greenland sharks.

KRISTYN: If we think
the creature might be migrating

in and out of the loch,

and maybe it's been away
for a while,

perhaps the shark
is still a candidate for Nessie.

But that DNA test makes things
a whole lot less likely.

ZAK: This study wasn't
completely fruitless though,

because they did find the DNA
of countless other species,

including
an incredibly large deposit

of another potential
Nessie candidate.

Across nearly 1,500 years
of sightings,

witnesses and scientists alike
have been fascinated

with the mystery
of Scotland's beloved Nessie.

But a closer look at results
from a 2019 DNA test

might finally reveal the secrets
of what's living in Loch Ness.

ZAK: Throughout the years,
since at least the 1960s,

and maybe even before,
modern technology has been used

to try and solve the mystery
of the Loch Ness Monster--

everything from sonar,
to thermal imaging,

to hydrophonic soundwaves.

But none of these techniques
have given us concrete results

or gotten us any closer
to legitimate answers.

However, anybody who has
ever watched a crime show

knows that the best evidence
to provide the identity

of the culprit
is DNA evidence.

LAURENCE: In 2019, a team
of scientists from New Zealand

finally complete
their DNA analysis of water

from Loch Ness.

While there's no trace
of Greenland sharks,

what they discover unleashes
new possibilities for Nessie.

They find about 3,000 species,
if you can believe it.

Most of those
are tiny plankton, roundworms,

nematodes, small crustaceans.

Of the larger fish,
they find salmon, pike,

stickleback, lamprey,
a few others.

They even find DNA
of land-based creatures

that sometimes end up
in the water

for one reason or another,
including dogs, cattle,

sheep, rabbits,
and even humans.

This tells us that this test
is very sensitive.

Even animals that rarely
go in the loch are detected.

But the largest amount
of DNA they find

that is detected
in almost every single sample

is eel DNA.

JONATHAN: There are a ton
of eels in Loch Ness.

It is one of the principle
spawning grounds

of the European eel.

Now, most of these eels,
they only grow

to be about 0.8 meters.

So, they're not
exactly monsters,

But could there be
a monster eel?

Very possible.

Every single sampling site that
we went to pretty much had eels.

And the sheer volume of it
was a bit of a surprise.

KRISTYN: The largest eel
in the region

is the European conger.

It can grow
to almost 10 feet long

and weigh up to 160 pounds.

Could that be Nessie?

JONATHAN:
Eels are migratory fish,

so if someone saw an eel
in Loch Ness,

it's pretty easy to assume
that they could think

that that's
the Loch Ness Monster.

ZAK: Once you have an eel
in mind, and you look back

at the videos and images
of Nessie,

you realize
it could be possible.

LAURENCE: Especially if
you analyze the way

both Nessie and eels move.

The Loch Ness Monster
has often been described

as a serpentine-like monster,

maybe snake-like,
or perhaps, eel-like.

If any animal could look
like a sea monster,

an eel is a prime candidate.

It really has a classic
serpentine look.

Eels move in a slithery,
sort of snake-like way,

where their body curves,
and that's exactly what people

say the Loch Ness Monster
looks like.

So, it's really possible
that they saw an eel

with those hump-like shapes,
and they thought,

"That's the Loch Ness Monster."

LAURENCE: A 2007 video shot by
retired engineer Gordon Holmes

seems to support this theory.

DUSTIN: In 2007, Holmes makes
some trips to Loch Ness

to perform some
amateur experiments,

just for fun.

KRISTYN: At first,
he records some sounds

using hydrophonic equipment.

Then he sets up a camera
to capture video of the lake,

but he doesn't find anything
out of the ordinary.

LAURENCE: That is,
until his visit on May 26th.

DUSTIN: Holmes spots
some movement in the water

as he's driving, and pulls over
and grabs his camcorder.

His footage clearly shows
some type of large animal

moving through the water.

Though it's hard to tell,
it appears as though it's moving

in a serpentine fashion,

almost slithering
through the loch.

KAREN: This is some
of the best video ever captured

of a creature on the surface
of Loch Ness.

Holmes purposely zooms
in and out while he's shooting

to make sure the shoreline
and other landmarks are visible,

so the footage
can be analyzed later.

LAURENCE: Holmes sends
his footage to a forensic team

to determine
the animal's size and speed.

They find that
it's 10 to 15 feet long

and swimming at a speed
of six miles per hour.

Based on movement analysis,
they find a strong likelihood

that this animal is an eel.

Eels are the most common animals
in the loch,

and it's very likely that most
of the sightings over the year

have been related to eels.

ZAK: At the time, this is
long before the discovery

of eel DNA in the loch,

so they come to this conclusion
all on their own.

KRISTYN: Eels can also appear
brownish gray in the water

and have very smooth skin
like the Nessie descriptions.

The so-called "humps"
that people see

could be the serpentine curves
of the eel as it swims.

And the whole
"long, thin neck" concept

could fit with the eel as well.

They have a long, thin
everything.

DUSTIN:
But at 10 to 15 feet long,

if Holmes' research
is correct,

that would still be an eel
of massive proportions.

And in fact, they did develop
an amazing new science

and a way to study
bodies of water

and what lives in them.

ZAK: But of course,
potentially identifying

the Loch Ness Monster brings
a ton more attention

to their research.

LAURENCE: When a DNA profile
of life in Loch Ness

is completed in 2019,

it uncovers a wide array
of species,

but it doesn't
identify everything.

Some of Nessie's
most passionate researchers

are quick to note that according
to the full 2019 report,

the source of 20%
of the DNA collected is unknown.

And that opens up a whole new
world of possibilities.

Maybe the monster isn't
a plesiosaur, or a shark,

or an eel, or any species

that we've even
encountered before.

All of the previous attempts
to prove that it is this animal

or this other animal
have been destined to fail

because it's none of these.

KAREN:
We may not know what it is

because we just don't know
what it is.

Based on all this
unidentified DNA,

could Nessie
be a completely undiscovered,

previously unknown species?

JONATHAN: If there's one thing
that all underwater explorers

and scientists can agree on,
it's that we have not found

all the species in the ocean.

There are hundreds of thousands,
maybe millions of species

that we haven't found
or classified yet.

There's stuff out there that
we don't know anything about.

LAURENCE: If Nessie's species
is unknown,

how can we ever identify it?

Pretty much the only way
we can properly identify

a new species--
whether it's a tiny insect

or a giant lake monster--
is to find a specimen.

That's how science proves
and classifies new animals,

plants, and even bacteria.

Either living or dead,
we have to capture one.

KRISTYN: As far as we can tell,
nobody has ever captured

a Loch Ness Monster.

There may have once
been those remains

on the Isle of Stronsay,

but we're not actually sure
it's the same animal.

And in any case,
none of that DNA survived.

So, there's no way to compare
the Stronsay Beast DNA

with the unknown DNA
that we have from the Loch.

DUSTIN: So, we're stuck
with trying to catch

this elusive animal
in Loch Ness.

But for 1,500 years
no one has even come close.

We're still trying to get
a good photograph,

let alone trap the thing.

LAURENCE:
The problem lies

in the incredibly challenging
conditions at Loch Ness.

JONATHAN: First off,
Loch Ness is huge.

It's 23 miles long,
it's a mile wide,

and the most important thing,
750 feet deep,

which is impressively deep
for any lake.

It contains more water
than any other lake in the UK.

In fact, it contains
as much water

as all the lakes
in England and Wales combined.

So, it's a large place
to look for a monster.

KAREN: But the size
isn't the only reason

it's hard to explore.

Loch Ness is full of peat,

which is organic matter
from plants

that's constantly
breaking down in water.

It makes the water dark brown,
almost black.

Visibility is only
a couple of feet at most.

And even if you were
to dive down for a look around,

the temperature
is not survivable.

Loch Ness has an average
surface temperature

of 42 degrees Fahrenheit.

And as soon as you get
about 20 feet down,

it has what is known
as a thermocline.

It's a stratification
of the water,

almost like an invisible wall,
where suddenly the temperature

can drop 10 or 20 degrees.

Without a very advanced
modern dry suit,

a diver could freeze to death
and drown in about six minutes.

KRISTYN: I'm not sure
that this thing

is possible
to catch in Loch Ness.

LAURENCE: But could another lake
linked to Loch Ness

by a waterway offer fresh hope

of capturing a creature
like Nessie?

According to some,
the answer is yes,

and Sweden's Storsjön Lake
is the ideal location.

DUSTIN: Both are freshwater
and fairly cold.

Both share similar
biological diversity,

oxygen levels, et cetera.

If something can live
in Loch Ness,

it can most likely
live here too.

LAURENCE: Like Loch Ness,
it has a long history

of monster sightings.

There have been centuries
of reported sightings

of a creature with
the same physical description.

In Swedish,
it's called Storsjöodjuret,

which literally translates
to "The Great Lake Monster."

It's first written about
on a runestone

that dates all the way back
to the year 1050.

It's got this depiction

of a long serpentine
water monster on it.

LAURENCE: Conditions in
the two lakes are similar,

but there's one
key difference.

Storsjön Lake
is much cleaner and clearer,

and much less hazardous
to explore.

LAURENCE: And that makes
spotting a monster much easier.

ZAK: Thanks to much more
favorable conditions,

the Storsjöodjuret
has been captured

easily on video
from far away,

most recently
in a 2008 documentary

that also shot infrared footage.

And attempts to track
the specimen

have already been mounted.

LAURENCE: Researchers at the
Lake Monster Center in Storsjön

plan to continue
their search efforts.

If they're successful,
all we have to do

is compare
the Swedish creature's DNA

to all the unknown DNA
from Loch Ness.

If any of it matches,
we've identified our monster

and discovered
a brand-new species.

That would be among
one of the most incredible

scientific discoveries
in history.

KAREN: As many
as 18,000 new species

are identified
every single year.

So, the possibility
is out there.

I hope one day we can
add Nessie to that list.

LAURENCE: Over long centuries,
many theories have emerged

about the origins and existence

of the mysterious
Loch Ness Monster.

Each offers an intriguing
possibility,

but none are airtight.

You say, hey,
maybe it's a plesiosaur,

but there's no evidence
any of them survived extinction,

and we'd see an air-breathing
creature much more often.

KAREN: So, maybe it's
a Greenland shark,

but shark DNA wasn't found
in the loch.

ZAK: Well, what about
all the eel DNA?

But could an eel,
even a giant one, grow that big?

What about the thing
that washed up in Stronsay?

Or the similar lake monster
in Sweden?

HEIDI: To be honest,
any one of these creatures

could be what was spotted
in Loch Ness,

or perhaps
it's more accurate to say

all of these things could be.

LAURENCE: What if it's not
Loch Ness Monster,

but monsters?

DUSTIN: We talk about
the Loch Ness Monster

as this monotypic creature,
like there's just one of it.

There's only ever been
one Nessie.

But given the time period,
1,500 years of sightings,

that's highly unlikely.

There's absolutely no reason
it has to be one thing--

and the same thing--
over centuries.

KRISTYN: Let's start
with the eel theory.

For sure, some of the things
that people have seen

in the loch over the years
have been eels.

Just look at
the Gordon Holmes footage,

and that's obvious.

KAREN: It's a common animal
in the loch,

and when you're scanning
from far away

looking for any kind
of movement on the surface,

a large swimming eel could
certainly catch your attention.

ZAK: How about
a Greenland shark?

Well, we know they're swimming
around in the North Sea,

and they can and do
sometimes go up river

in the freshwater areas.

It's quite likely
a predator like that

could follow a bunch of salmon
into the River Ness

and could conceivably make it
all the way into the loch.

A lot of animals
that sharks like to eat

make that trip,
including seals.

While there wasn't any shark DNA
in 2019,

there is still a good chance
that a shark has been spotted

in the loch across the thousands
of other sightings.

LAURENCE: And what about
the plesiosaur theory?

HEIDI: I don't necessarily think

there's a living,
breathing plesiosaur

that is swimming around there.

But I do think the plesiosaur
may be what's behind the legend.

Scotland and the UK in general

are teeming
with plesiosaur fossils--

fully-intact skeletons
of creatures

that back in the Middle Ages
would have been assumed

to be monsters.

Water beasts,
just like Saint Columba saw.

Imagine in 500 or 600 AD,

you stumble upon the remains
of a plesiosaur.

You would certainly tell your
buddies back at the ale house

about the crazy
giant long-necked creature.

It's quite possible that
this tale eventually morphed

into the Loch Ness Monster
legend.

HEIDI:
As for the Stronsay Beast,

whatever it is,
it really doesn't matter.

If it washed up
on the shore of the island,

we know there's a direct path
of waterway

that connects back
to the Loch Ness.

KRISTYN: And any
migratory creature,

whether it's a shark, a whale,
or anything less,

could be swimming back and forth
from the sea to the loch.

HEIDI:
Some of the Loch Ness sightings

could be the same animal.

LAURENCE: Or perhaps
an unidentified animal

from even further away.

KAREN: Across 1,500 years,
some of the Loch Ness sightings

may well be an unidentified
new species.

Even the DNA results
bear that out.

They can't identify
every living thing in the loch.

KRISTYN: But if Sweden's
Storsjön Lake

is hiding the same species,

maybe we'll have
an incredible discovery soon.

DUSTIN: Still, even if they
identify the Storsjöodjuret

and identify one
in Loch Ness as well,

that doesn't mean that
Gordon Holmes didn't see an eel,

or others didn't see
other animals.

A new species
would be a revelation,

but remain only one piece
of the puzzle.

HEIDI: And still, there will
always be those people

who believe Nessie is a hoax.

We know for a fact
that plenty of Nessie witnesses

have been duped by hoaxes.

It happened to a sonar team
that found a movie prop.

And in fact, it happened
to millions of people

around the globe, thanks to
the surgeon's photograph.

DUSTIN: So, yes,
Nessie is also a hoax,

but not just a hoax.

There's much more
to the monster than that.

KAREN: One day, we may get
the perfect biopsy,

the perfect picture,
the perfect bone specimen,

or maybe a strange
long-necked creature

will just walk right out
of the loch and say hello.

And when that day comes,
it'll be time

to break out the champagne.

ZAK: But until then, I think
we shouldn't limit our minds

to what Nessie could
or couldn't be.

Because it could be
something new next year.

DUSTIN: The possibilities
are endless,

and that is what
has kept people

fascinated with Nessie
for so long.

Despite the many challenges,

thousands of amateur
and professional researchers

still spend time
at Loch Ness every year

hoping to unmask the monster.

Perhaps modern technology
will soon provide us

with a clear picture
of what's hiding in the depths.

Until then, there's no shortage
of people willing to look.

I'm Laurence Fishburne.

Thank you for watching
"History's Greatest Mysteries."