Original subtitles

[William Shatner] Underwater caves

described as the entryway to the underworld.

Gigantic creatures

found deep beneath the thick ice of Antarctica.

And a man-made lake

where swimmers disappear without a trace.

Twisting rivers,

ominous lakes

and seemingly bottomless oceans.

For centuries, many cultures have wondered

what lies beneath Earth's aquatic surface.

And with the advances in technology,

scientists have delved even deeper into the world's

most mysterious waters, searching for answers.

From lost cities and strange creatures

to dark and deadly anomalies,

what secrets are hidden

in our planet's vast underwater world?

Well, that is what we'll try and find out.

♪ ♪

[Shatner reads on-screen text]

Billionaire and underwater explorer Victor Vescovo

boards an advanced deep-sea submersible

known as the Limiting Factor,

and descends underwater.

His mission is to explore the Challenger Deep,

an underwater valley that is the deepest point on the planet.

[Victor Vescovo] I was the fourth person to dive

to the bottom of Challenger Deep.

Within the first thousand meters,

it goes from being brilliant sunshine in the Pacific

to pretty much fully black.

So you descend in the water column, as we call it,

for up to four hours,

steadily going down, watching

that depthometer creep and creep and creep.

And you get to the bottom and then you

check in with the surface, tell them that you're okay.

[cheering]

At that point, it takes seven seconds for the transmission

to actually get to the surface,

and seven seconds for it to go down.

It's such an incredible feeling of relief

and a sense of incredible achievement

that, "Oh, my gosh, we actually did it."

[Josh Young] Challenger Deep is the most deep, dark

and dangerous place on the planet.

When you get to the bottom, the pressure is

the equivalent of having

200 747s stacked on top of you.

Unimaginable crush pressure there.

You need a properly engineered submersible

that can go down, withstand the pressure,

stay down there

and continue to explore these depths.

[Monty Halls] To get to these locations--

it's an extraordinary undertaking, that,

and should be celebrated.

They are incredibly difficult

to get to, they're extremely dangerous,

they're very hostile to people.

We don't belong down there.

[Shatner] The ocean is a vast expanse

that is almost unimaginable in scope.

And although humans have been traveling

across the high seas for thousands of years,

we still only know a fraction

of what lies beneath the waves.

[Vescovo] The most important thing I think

I try to get people to realize is that the ocean is big.

I mean really big.

Bigger than you can put your head around.

It is 70% of planet Earth.

And it's three dimensional.

It's not a two dimensional surface like the land is.

And so, 80% of it is still completely

unmapped and unexplored.

[Halls] The deep sea

remains the last great frontier

for us as a species.

We know way more about the surface of the Moon,

way more about the surface of the other planets

than we do the deepest spots

in the ocean.

It's a mystery we've just started to unravel.

[Young] The allure of the deep sea is that

it holds something in everyone's imagination.

Not fully knowing what is there

enables everyone to come up with

their own vision of what might be there.

What creatures might live down there.

Might there be sunken ships and gold,

and where might that be?

That is what sparks the curiosity

that we need to keep exploring

and to keep investigating

what's down there? What's out there?

[Shatner] The recent dives to the bottom of the ocean

have shed new light into the darkness of its depths.

But these voyages are just the latest chapter

in mankind's long

quest to uncover what secrets are held in the seas.

In fact, our fascination with the ocean

goes back thousands of years.

[Lynne McNeill] Throughout history

and cross-culturally as well,

we see a really consistent pattern of belief

that under the water is an entirely other world.

Full of creatures

like a Kraken or a Leviathan.

And it's not just oceans.

Lakes are always populated with these monstrous creatures,

like the Loch Ness Monster.

The message we get is that no body of water is safe.

[Michael Tuttle] The understandings of the seas

and oceans over time

has changed dramatically.

The ocean

was basically seen by seafaring people,

like the ancient Greeks were or ancient Phoenicians were,

as the big, bad, black sea.

They didn't have the ships to go against

the currents and the winds.

And if you sailed far enough, you'd die.

[Robert Schoch] For so long, no one really knew

what the extent of the oceans were, what's under them.

Even in the time of Columbus, late 15th century,

people were worried,

some people thought the Earth was flat,

that you could literally get to the end of the ocean

and fall off the edge.

[Shatner] Humanity has always been humbled

by the vast power of the ocean.

But during the scientific revolution in the 16th century,

we started to get a better understanding

of the underwater world.

In 1521, Portuguese explorer Ferdinand Magellan

attempted to measure the depth of the ocean

by attaching a line

to a cannonball and tossing it over the side of his ship.

After lowering the cannonball 2,400 feet,

Magellan declared that the ocean was immeasurably deep.

Magellan went out and tried to measure the depth of the oceans.

He wasn't largely successful with that,

but it sort of opened the door

that, wow, this is really deep

and we need to do more exploration.

That was furthered later

with the HMS Challenger expedition in the 1870s

that went all the way around the world

to explore the deep oceans.

And the most significant thing it found was the deepest part,

which is the Challenger Deep,

which was named after the expedition.

Over time,

there became more of a curiosity to the oceans.

To want to go down and to be able to go down

to see what was there.

[Shatner] In the 20th century,

the development of undersea submersibles

ushered in a new era

of unprecedented underwater exploration.

[Young] The evolution of a deep ocean submersible started

in 1930 when a bathysphere was created, where a man

was put inside of a, essentially, a vessel

and dipped down into the ocean, held by a tether.

That was furthered later by the bathyscaphe in 1960,

the Trieste, which took Don Walsh and Jacques Piccard

to the bottom of the Challenger Deep

for the first time ever.

[Shatner] Today, underwater archaeologists and explorers

are using the latest submersible technology

to try to unravel the mysteries that lie

within the ocean.

And many experts believe

that they are on the cusp of making

dramatic new discoveries on the sea floor.

[Vescovo] My hopes for ocean exploration in the near term

is to bring the very deep places, the very

dangerous places to a point of accessibility

where we can take any scientists down to them to explore them.

And also there's a huge project underway

called the 2030 Sea Floor Initiative

where a bunch of different scientists

and people like myself, we're trying to help map the seafloor.

[Shatner] The Seabed 2030 initiative

is gathering information collected all over the world

by science vessels, merchant ships

and underwater drones.

Their goal is to map the entire ocean floor

by the year 2030,

a feat that seemed impossible for most of human history.

[Vescovo] Technology is always the key.

Technology allows us to do things

that we couldn't do before,

and see those things that no one has ever seen before.

It's human progress,

and really pushing ourselves to the next level.

[Shatner] It's thrilling to think

that Earth's deep oceans are a future frontier.

But what lies below the sea's surface

is not the only underwater environment

that captivates the imagination.

that captivates the imagination.

Because there's a network of water-filled caves

in Central America

that some believe are an entrance

to the afterworld.

[Shatner reads on-screen text]

A six-mile-wide space rock smashes into Earth...

...and sends billions of tons of rock and debris

into the atmosphere,

generating tsunamis that are a half a mile high.

This apocalyptic impact

kills 75% of all life on the planet

and creates about 6,000 sinkholes

and underwater cave systems known as cenotes.

[Lewis Land] Cenotes

are one of the principal sources of water in the Yucatán.

So, all of the movement of water

in the Yucatán, practically all the movement of water

water in the Yucatán, occurs in the subsurface.

A cenote is literally a hole in the ground.

And it's usually flooded at the bottom.

The ancient Mayans used the cenotes

on the Yucatán Peninsula for a water supply.

And the cenotes also have cultural significance

because of the role that they played

in Mayan religion and Mayan agriculture.

[Shatner] Cenotes were sacred

to the ancient Mayan civilization,

who existed in the region for about 3,500 years

starting around 2000 BC.

These natural wells of fresh water

were essential for growing crops and clean drinking water.

In fact, one of the Mayans' most important cities

on the Yucatan Peninsula was called Mayapan.

And it was purposefully constructed

around these vital water sources.

[McNeill] Mayapan was a really

sprawling, beautiful city

built entirely inside a protective wall.

And within that wall that surrounds it,

there are a number of cenotes.

Which, of course, if you're an ancient civilization

looking for a fresh water supply,

this would have been a phenomenal place

to build your walled city and make sure that you contain

all of those bodies of water.

But what's really interesting

is that there is one cenote

that is outside the city walls,

and this particular cenote is known as Sac Uayum.

And it's not incidentally outside the city walls.

The city walls actually zigzag in this really awkward way

around this one pool of water.

[Shatner] Why would the ancient Mayans

go through all the effort to build around this one cenote

known as Sac Uayum?

Perhaps answers can be found with strange tales

that modern-day descendants of the Maya still tell to this day.

[Russell] We've investigated

dozens of cenotes across the site.

There's several dozen within the city walls

in Mayapan, but...

We began to hear stories about,

you know, the cenote that was outside of the city wall

that seemed to be kind of deliberately excluded.

There's several kind of stories I was hearing about Sac Uayum.

It's guarded by this important

and powerful being.

That it was protected by a feathered serpent.

That people had seen the feathered serpent

up in the trees and watched it kind of fly up in the air

and dive down into the cenote when they approached.

[Shatner] In 2013,

anthropologist Bradley Russell and his team

prepared to learn more about this storied cenote

and its hidden secrets, and descended into Sac Uayum.

[Russell] It's about four stories down to water.

So, we knew we were gonna have to rappel in,

get in the water, dive.

And we noticed that there was a small opening.

It was a tunnel that would lead us to something.

So, you know, you went from this large open chamber

into this narrow tube,

and then you pass through that, and it opens up

into this massive, beautiful, white-walled,

gorgeous second chamber

that's filled with water the whole way to the ceiling.

We began to explore that, and we realized

pretty quickly that there were

human remains in the second chamber,

including several skulls that are sitting

just completely face up staring right at you.

It was unusual because there was no logical way

that you could have put a body in there.

We didn't really understand at first

how there could be human remains in there.

It turns out that the first chamber

sits a little bit above

a section of the lower chamber.

And what seems to have happened was that the floor

of the first chamber caved in,

brought down stone in kind of a slope

and then human remains

that are lighter than the rock settled out.

When we analyzed samples of the human remains

back in the lab, we do a count

that we call the minimum number of individuals-- the MNI.

And the MNI we came away with was, like, 19.

So, we know that there's close to a couple of dozen individuals

that are there.

And when we did radiocarbon dating on their bones

that we had across the collection,

they fell consistently about 1350 AD.

We found that it was mixed age and mixed sex,

so every member of society, essentially,

was represented relatively equally.

[Heinerth] The Mayans considered cenotes

as the entryway to a place they called Xibalba,

which was really their form of the underworld, or hell.

So, cenotes were sacred places where,

sure, there were accidental drownings,

but there were also intentional sacrifice rituals,

potentially to seek their gods to send water

in a time of drought.

[Shatner] It's disturbing to consider

what may have happened at Sac Uayum

to appease the ancient gods.

But for now, the mystery

surrounding this underwater underground world endures.

[Russell] We didn't find any evidence

for decapitation or things that might be

the violence of the actual sacrificial act.

So, we were needing another explanation.

And what we've concluded is that

there was probably a series of disease outbreaks

around 1350 AD,

and somebody needed to deal with the bodies quickly, en masse.

And people chose cenote Sac Uayum

to put the bodies into.

So, the mystery of why they're there is

slowly being clarified, but...

I would never say at this point that we're 100% certain

that that's what it is.

[Shatner reads on-screen text]

The sun rises over the hills

surrounding an ancient body of water

known as Lake Nyos

and reveals an apocalyptic scene.

In nearby villages, lifeless bodies are strewn about

as if a mysterious force had swept across the land,

killing nearly everything in its path.

[McGee] There was

a terrifying geological catastrophe that occurred.

Something disrupted this lake.

Locals reported a rumbling sound

and what might be described as an explosion

as the lake suddenly came to life,

and anyone who was caught in its path

instantly dropped dead.

[Shatner] The death toll was staggering.

It's estimated around 1,700 people and 3,500 animals

were killed across a 14-mile radius.

With no obvious cause of death,

an international team of scientists,

including American biologist George Kling,

was dispatched to investigate.

We really didn't know what had happened, what had caused this.

And the lake itself was

very reddish orange,

like a rust color

that we really don't see very often in lakes.

And there was a lot of damage around the shoreline

from some large wave

that must have been produced with enough force

to wash away all the vegetation and soil down to bare rock.

And lakes just don't explode like that.

[Shatner] What exploded out of Lake Nyos,

killing everything in its path?

Given that the lake was formed in an ancient volcanic crater,

investigators feared that an eruption deep underground

released a surge of deadly gas.

[Kling] Many of the survivors

reported smelling rotten eggs or gunpowder--

and that's an unmistakable smell of sulfur--

and they reported feeling warm.

And we know volcanoes produce a lot of sulfur gas

and a lot of heat.

But when we started analyzing our samples,

we found no sulfur in the lake water.

We found no excess sulfur in the plants around the lake

that had been exposed to this gas cloud.

And when the Army pathologists did autopsies,

they found no evidence that people

were poisoned by sulfur gas.

[Shatner] No poisoning by sulfur gas?

Experts were left wondering

if the cause of this deadly disaster

was even geological at all.

Local rumors swirled about

chemical spills, weapon tests,

even stories about vengeful spirits in the lake.

But George Kling found something intriguing

buried in old medical reports.

A clue pointing to a rather unlikely culprit:

a gas that we all produce when we exhale.

Carbon dioxide, otherwise known as CO2.

[Kling] We ran across some older medical literature

that had used high concentrations of CO2

to test for oxygen stress in fighter pilots.

And it turns out that CO2 above concentrations

of about six percent acts as a sensory hallucinogen.

And one of the most common reports from the fighter pilots

was that they smelled rotten eggs and gunpowder

and that they felt very warm.

So, we knew that this was a CO2 release,

and we suspected that the gas was held in the lake.

It turns out that the lake itself

could hold a huge amount of gas in the bottom waters.

[Shatner] Kling's tests reveal

that Lake Nyos was primed for disaster.

Over centuries,

the lake had become a pressurized chamber

of carbon dioxide,

and when that chamber exploded,

it released a massive wave of suffocating gas

that raced across the land at over 60 miles per hour.

Lake Nyos, as it turns out,

was supercharged in carbon dioxide,

much like a soda can if you shook it up

before you opened it.

So, anyone unfortunate to be caught in its path

couldn't breathe.

[Kling] One of the things that made this event so deadly,

was that this CO2 gas cloud was enormous, first off,

but because it was heavier than air,

it flowed out of the lake

and down the river valleys very quickly,

so even if people had seen the cloud coming,

they couldn't have gotten out of the way.

And people just, essentially,

died in place.

Lake Nyos was vulnerable to this kind of an event

because it was formed by volcanic activity.

And it's also very deep.

So, those deep waters could store a lot of gas.

But once we have the gas build up,

we have to have a trigger,

and this could be any number of things.

For example, it could be a landslide

that caused the gas burst,

but we'll probably never know for sure

what triggered this disaster.

[Shatner] Based on Kling's discovery,

Lake Nyos is now monitored around the clock

to help anticipate another deadly gas event.

But solving the Lake Nyos disaster

reveals a far more terrifying question.

With more lakes potentially primed

for the same kind of catastrophe,

when and where could this happen again?

Lake Kivu in East Africa

is the nasty big brother of Lake Nyos.

It's 1,600 times larger,

it has a thousand times more gas in it.

And because there are millions of people

living around the shoreline of that lake,

it's the largest ticking time bomb in the world.

There are active volcanoes in the area,

and these volcanoes could destabilize it

and trigger a gas burst.

We haven't looked at every single lake in the world.

But we know now enough about

what kinds of lakes could be dangerous.

[McGee] Knowing that this is a process

that the Earth can throw at us,

it's natural to wonder, are other lakes susceptible?

The good news is it doesn't happen everywhere.

But the bad news is if there's one that we don't know about,

we need to find it first before it lets us know

it's there in all the worst ways.

Could such a puzzling catastrophe

like the explosion at Lake Nyos happen again?

It's a distinct possibility.

But there's another lake

of a very different kind where strange disappearances

leave many asking

if the place is cursed.

[Shatner reads on-screen text]

Nestled beside the sleepy suburbs of Clinton Township

lies Round Valley Reservoir.

First formed in 1960 as a primary water source,

this man-made lake is beloved by locals

for its great fishing and scenic views.

But many believe this idyllic watering hole

conceals a deadly secret.

For more than 40 years,

people have been disappearing in Round Valley Reservoir.

And not just a few.

More than two dozen men have been lost

beneath these placid waters, never to be seen again.

Locals do believe that this lake is cursed,

and it's easy to understand why,

with so many tragic deaths surrounding it

in just about 40 years.

And while I can't be sure if it's cursed,

there's always one thing that's given me the chills.

I heard someone say that when one body is found

at Round Valley Reservoir, another quickly replaces it.

We don't even know for sure how many bodies there really are.

[indistinct radio chatter]

When I worked in news,

I would hear the police scanner crackle to life

with "Round Valley, fishermen, trouble,

boat or somebody has gone under the water."

It's a creepy, horrible feeling when you hear this,

because you know that 90% of the time,

this is not going to end well.

I can't explain why

these people at the bottom of the lake haven't been found,

especially after searching for them

with such a degree of intensity.

Even after bringing in cadaver-sniffing dogs,

using sonar technology and submarines

to crawl the lake, uh, there was no sign.

It's almost as if some of these people

disappeared without a trace.

And an interesting thing,

if you're looking for bones in Round Valley,

is that you aren't necessarily going to find

a fisherman who disappeared 13 years ago,

you may find a bone that was in the ground

long before Round Valley became a reservoir.

[Shatner] Bones, from a time before

Round Valley became a reservoir?

There are some who believe that these bones may have been

the very reason the bodies of those

who have disappeared here have never been found,

and that the lake's refusal to give up its victims

is actually an act of revenge.

There was a town here once.

For centuries, people put down roots in this valley.

It was very fertile and rich farmland.

There were thousands of acres,

and people grew their own food, they raised their animals.

Then in the 1950s, there was a drought in New Jersey.

And they needed a source of water for,

predominantly, Newark, but the surrounding area as well.

And so, they had to fill in somewhere,

and Round Valley, they believed, was the best choice.

People were opposed to the reservoir being built.

It was a small farming community, very close-knit,

and no one wanted to leave their homes.

Most of the homes were eventually razed or moved.

[Hill] Their homes were either torn down

or they were put on flatbeds and taken out of the valley,

and that construction started on the reservoir.

In the 1960s, they started filling it.

There was a lot of bad feeling here when...

when the landowners were pushed out of their valley.

Did these ill feelings carry over?

There are people who will say, "Yes, they did."

There are people who come here who think the town

is still here.

They still think they see that church steeple

and that barn silo underneath the water.

Are they seeing it?

Not really. They were torn down.

But the foundations were left in place.

Of course there were fence posts,

there were some things left below.

When you're at Round Valley, you feel the spirit

of the people who came before you.

There is a presence here

that can make you feel a little disconcerting.

Some local people call Round Valley

the Bermuda Triangle of New Jersey,

because as much as this is a place of great beauty

and great enjoyment,

it's also a place where death happens...

...really more than it should.

[Shatner] The idea that any body of water,

let alone a man-made one less than a century old

could somehow be imbued with a deadly curse

seems far-fetched, to say the least.

And yet outlandish and presumably irrational

notions such as these have been held

by nearly every culture throughout history.

But why?

A curse has to be believed in order for it to have power.

It's kind of like hypnosis. You have to be willing

to go under hypnosis in order for it to actually be effective.

So, maybe these curses

are created by us, by our imagination,

by us trying to deal with the mystery of nature.

It's just a game that we're playing,

but we ascribe meaning to it.

So, if we ascribe meaning to a curse,

could that actually make the curse real?

[Shatner] Although it may be human nature

to blame inexplicable tragedies on some sort of dark force,

according to skeptics, there's nothing supernatural

about the disappearances at Round Valley Reservoir.

They claim that these strange occurrences

must have a perfectly rational explanation.

[Hill] Some people

who live around here think it's more

a matter of respecting your environment.

And when the wind swirls, you can get waves

up to three feet tall on this reservoir.

And that's where people get in trouble.

They're not expecting it.

In my career, I've handled anything from, uh,

plane crashes, homicides, suicides,

uh, you know, lost children.

But when you're out there in a small boat

and there's fog coming across the lake,

it can be very eerie at times.

You have these 40 mile per hour winds that come up

out of no place.

They only allow small boats.

You have excessively cold water,

which leads to hypothermia.

I can guarantee probably nine out of ten people

that are out on this lake don't wear their life preservers.

I think it's because of those factors.

And you know what? Just plain bad luck.

Period.

[Shatner] So, where did the bodies of the lost men

of Round Valley Reservoir go?

Could it be that they're merely trapped

somewhere deep beneath the lake's surface

in a place searchers haven't yet looked?

Or are they really victims of a deadly curse?

[Shatner reads on-screen text]

After 20 years of drilling,

scientists make a remarkable discovery.

Locked deep beneath the ice for what some estimate

to be 20 million years,

scientists reach an extraordinary body of water

known as Lake Vostok.

Lake Vostok is the largest subglacial lake

in Antarctica and sits about 13,000 feet

below the surface of the ice sheet above.

A subglacial lake is one that's formed underneath ice.

Subglacial lakes are a real mystery.

We've only explored a handful of them,

and it's very difficult to explore

these hidden environments.

They represent a natural laboratory.

What happens to life if you cut it off

from the rest of the world for millions of years?

[Mike MacFerrin] When they pulled up water

from Lake Vostok, they found microbes in there

that had evolved completely independently

from nearly all other life on Earth.

Lake Vostok is so remote,

so isolated from the rest of the planet.

If life could evolve here, it could evolve nearly anywhere.

It was the closest thing we've ever found

to life on another planet.

[Shatner] While Lake Vostok is a tremendous discovery,

it is just one of many pristine places in Antarctica

where scientists have found not just microbial life-forms

but creatures of all sizes

that have never been seen before.

[Griffiths] One of the amazing things about working

in Antarctica as a marine biologist

is we get to discover new species.

If we go to unexplored areas or places that are much deeper,

80 or 90% of the species we pull up from the sea

are new to science.

And that includes some really strange-looking organisms.

We have the strawberry feather star.

Its central part of its body resembles a strawberry.

I even have two species of sea cucumber named after me

because they were starting to run out of things

to name the new species we'd found.

And so, it's not a question of "Will we find new species?"

it's a question of "How many new species

will we find every time we go?"

[MacFerrin] Every time we look at a new pocket of seawater

underneath the ice in Antarctica,

we find something we'd never seen before.

Just a few years ago, they found sea spider crabs

that have legs up to 20 feet.

They found two-foot-wide sea stars.

They found jellyfish with 12-foot-long tentacles.

Many of these reach sizes

that are incomparable to anywhere else on Earth.

[Shatner] The cold, undisturbed waters

around Antarctica make an excellent breeding ground

for massive creatures.

Blue whales, the largest animals to ever live on our planet,

roam these waters.

And even the mysterious and elusive colossal squid

can be found here.

[Griffiths] Colossal squid are enormous creatures

that are at least 33 feet long,

and they have

the largest eyeballs of any creature on the planet.

We've only seen a few of these organisms in real life,

but it opens so many questions about

how large animals can be found

in some of the most inhospitable parts of Antarctica.

[Shatner reads on-screen text]

The Argentina Antarctic Institute

completes their excavation of one of the most extraordinary

and massive fossils ever discovered.

It is the skeleton of a sea creature

that swam in Antarctic waters 66 million years ago

called Elasmosaurus.

Elasmosaurus was a real sea monster

swimming around the Antarctic.

It's the heaviest marine reptile fossil

that's been found around Antarctica.

It was up to 40 feet long

and possibly 15 tons worth of animal.

It was thought to have lived right up to the extinction event

that killed the dinosaurs,

but it was the largest swimming reptile

in the oceans around Antarctica.

[Collins] When the story hit the news,

people started saying, "Doesn't this resemble

the Loch Ness Monster?

Doesn't this resemble other sea monsters

and lake monsters around the world?"

begging the question of whether creatures like the Elasmosaurus

still exist out there in the sea caves

of Antarctica to this day.

[Lance Geiger] We know this massive critter

lived there, right, so...

things that you might call a monster,

could they live under that-- those ice shelves?

Of course they could.

Ninety-eight percent of the ocean bottom

underneath these huge ice sheets off of Antarctica

are completely unexplored.

There's absolutely going to be stuff

that we've never seen before that surprises us

and that tells us more about life on our planet.

[Shatner] Perched on the shore of the Arabian Sea

sits the modern city of Dwarka.

It was named after a legendary city

that was also called Dwarka.

The sacred Hindu text the Mahabharata

explains that the legendary city of Dwarka

was said to be the dwelling place of Lord Krishna

before it sank into the sea

following a fantastic battle in the sky

between Krishna and another Hindu god, Lord Salva.

For centuries, that story was believed to be merely a legend.

That is, until 1983,

when underwater ruins were discovered off the coast.

Ruins which suggest that the legendary city of Dwarka

was not a myth but rather a real place.

[Richard Bates] S.R. Rao

was an archaeologist-- a marine archaeologist--

working with the Archaeology Institute in India.

And he had started the exploration from the shore

of present-day Dwarka.

And on the floor of the ocean, on the seafloor,

he found wall structures,

blocks three-foot by three-foot, probably a foot thick,

stacked as if they were building continuous wall structures.

They could be city walls, they could be

street building walls,

um, they could be walls of temples.

[Deepak Shimkhada] The archaeologists are now

saying that they are perhaps,

uh, dateable to, uh, 9000 BCE.

If it is true, the archaeological facts

support this story,

and that is what makes it more interesting

and more significant, uh, this discovery.

[Shatner] The discovery of sunken ruins

off the coast of Dwarka is proof

that underwater exploration can turn some myths into reality.

Many experts believe that Dwarka is just the tip of the iceberg

and that there are even more secrets lurking in the deep

that could challenge our understanding

of both our planet and human history.

[Young] The biggest unanswered question

regarding the oceans is

now that we've opened this door to this scientific exploration,

what can be found that will have some impact on our own lives?

Well, the oceans-- they drive weather

and regulate temperature

in ways that we don't fully understand now,

and the only way that we're going to completely understand

is to go down there and to gather more data.

And that's just one example.

The ocean is constantly throwing up surprises.

[Vescovo] Will we find remnants of an ancient civilization

that no one knew about?

I don't know, but that unknown is what drives me,

because there's a chance

that we'll find something revolutionary

at the bottom of the ocean that no one

had ever thought of before.

[Halls] Even though we are the first generation

ever to explore under the sea

with any level of technology and rigor,

the deep sea still eludes us.

And the good thing is it's becoming

more and more accessible.

Imagine what we're gonna discover in the next 50 years.

It's fascinating to know

that a land once considered the stuff of legends

is actually real,

hidden for centuries like an underwater time capsule.

The mysteries lying beneath the surface

of our watery planet are countless,

from lost ancient cities to undiscovered worlds

filled with strange and exotic creatures.

What will further underwater exploration reveal

about Earth's oceans?

and our ability to survive in the deep, dark sea?

The possibilities are as vast as the water itself,

and for now,

remain unexplained.

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