Original subtitles

NARRATOR: The China Seas.

Ringed by the countries of southeast Asia, these are some of the

most fiercely contested waters on earth.

Beneath the waves, the shattered remains of epic battles.

JAMES: It's as if you took hundreds of ships and put them through a blender.

NARRATOR: Mysterious treasures, and technological wonders all

hidden from view...

until now.

Imagine if we could empty the oceans, letting the water drain away to

reveal the secrets of the sea floor.

Now, we can.

Using the latest underwater scanning technology,

piercing the deep oceans and turning accurate data into 3D images.

How did America defeat the biggest battleship of World War II?

JAMES: It was huge.

It was powerful, it was fast.

For the Americans facing it, it was a brute of a battleship.

NARRATOR: What's the truth behind the strange disappearance of the

mightiest invasion force of ancient times?

ERIC: One of the biggest disasters in the history of maritime warfare.

NARRATOR: And how do you protect the Worldwide Web from the perils of nature?

To compete or collaborate?

Trade or invade?

These twin human instincts have defined the China Seas for centuries.

As these turbulent waters begin to drain away,

140 miles south of Japan, they reveal a top-secret battleship.

The biggest ever put to sea.

What were its secrets?

And why couldn't they save the lives of 3,000 men?

October 1944, two giant warships sail towards the biggest

naval battle in history.

The mighty Yamato and its twin, Musashi.

-The size of the Yamato is, is breathtaking.

The Yamato and its sister ship, Musashi, were by far the biggest

battleships ever built.

NARRATOR: Almost 900 feet long, 127 feet wide,

these super battleships dwarf their opponents.

Their hulls are protected by an incredible 16 inches of armor plate.

And every part of them bristles with weapons.

On the bow, two giant turrets.

Then over 100 smaller guns.

Before a third turret.

They are the biggest floating fortresses ever put to sea.

As the flagship of the Imperial Japanese Navy, Yamato carries the seal

of the Emperor himself.

A golden chrysanthemum.

JAMES: Yamato comes from the term Yamato-Damashii, which is the national spirit of Japan.

It was literally the embodiment of Japan itself.

NARRATOR: Yamato isn't just big, it's also top secret.

ERIC: The Japanese took enormous measures to keep the Yamato secret from foreign

navies, even to the extent of, of, of putting up a building so that western naval attaches

could not see the ship under construction.

NARRATOR: Even Yamato's commanding officers aren't told its true size.

Its secrets, whatever they may be, are to be protected at all cost.

MARK: And they were successful in this because for the entire war,

the Americans had no idea of the ship's true size or the size of the

guns that she carried.

NARRATOR: Japan's secret battleships are put to the test in one of the biggest

naval battles of World War II.

Three years after Japan bombs Pearl Harbor,

the Pacific War is about to reach its peak.

Advancing towards Japan,

US and Australian forces launch an invasion of the Philippines.

Yamato and Musashi lead the Japanese fleet as it tries to stop the

allies in their tracks.

The Battle of Leyte Gulf in October 1944 is the biggest naval fight in history.

An epic slugfest of 300 ships.

ERIC: Leyte Gulf was the last chance the Japanese fleet had to stop

the American advance.

NARRATOR: Yamato draws first blood.

Its big guns batter the US carrier Gambier Bay, sending it to the sea floor.

The Allies respond with cannons, torpedoes and aircraft.

A massive barrage of firepower that destroys 26 Japanese ships...

and damages dozens more.

MARK: It marked the end of the Japanese Navy as an effective fighting force.

NARRATOR: Yamato is hit...

but is saved by its immensely strong armor.

Musashi isn't so lucky.

It sinks under an onslaught of American bombs and torpedoes,

and 1,000 crew members are killed.

On the brink of defeat, the Japanese now resort to a new and shocking tactic.

They call it kamikaze.

JAMES: Thousands of young men dive their aircraft onto the decks of enemy ships.

NARRATOR: They believe that their self-sacrifice will save Japan.

But it's not enough to hold back the US forces.

After their victory at Leyte Gulf, the Americans reached Japan's doorstep,

the outlying islands of Okinawa.

Japan sends Yamato into battle once again.

On the 7th of April 1945,

it powers towards its destiny.

With orders to intercept the invaders and fight to the death.

The ultimate kamikaze mission.

JAMES: This huge ship, this ultimate battleship,

is sent on a one-way mission to turn itself into a giant gun battery

to try to keep the American ships away.

NARRATOR: But Yamato never makes it to Okinawa.

The Americans launch a surprise attack, with overwhelming force.

The super battleship's size and incredible strength can't save it this time.

Two hours after the first wave of bombs, the flagship of the

Imperial Japanese Navy plunges below the waves.

So, what were Yamato's secrets and why couldn't they save the ship?

Half a century later,

French and Japanese wreck explorers set out to unlock the mystery.

Sonar readings confirm wreckage on the seabed 140 miles south of Japan.

But the ghostly shadow gives little away.

They deploy a submarine.

As it descends into the darkness, its lights pick out a strange shape.

NARRATOR: Could these giant twisted pieces of metal really belong to Yamato?

They search for proof.

-Yes.

JAMES: As one who in the world shipwreck community watched those first images come back,

it was striking and powerful.

NARRATOR: Amongst the scattered debris...

reminders of the fate of the ship's 3,000 man crew.

Yamato is Japan's worst naval tragedy.

Using detailed sonar data from this expedition,

along with the latest computer imaging technology,

it's possible to drain the water from the China Seas,

to reveal one of the biggest wreck sites in the world.

And finally, discover the secrets of Yamato.

First, the Emperor's seal comes clearly into view.

Then, its gigantic propellers,

each stretching 20 feet across.

And shockingly, the final agonies of this mammoth warship are laid bare.

It is completely ripped apart.

JAMES: The violent death of Yamato and the sprawled corpse of the battleship,

makes for a compelling image because the ship was literally broken apart into chunks,

and that's what you see on the bottom.

NARRATOR: So, what is Yamato's big secret?

Experts scour the site to appreciate its sheer scale.

And the incredible thickness of its armored hull.

But they believe there's something else still hidden, and to see it means draining

not only the ocean, but the seabed itself.

To reveal these.

When Yamato was built, the Allies assumed it was fitted with 15-inch cannons,

common on battleships of the time.

But they were wrong.

Yamato's cannons are actually 18 inches, the biggest and

most powerful ever fitted to a warship.

Each can fire a shell the weight of a car, for almost 30 miles.

JAMES: To have 18-inch guns on a battleship,

means not only do you have bigger guns than other folks,

you have guns that can shoot farther, you have guns that can shoot

with more punch.

So, it's, it's a tremendous tactical advantage for the Japanese in the

age of the battleship.

NARRATOR: Kazushi Hiro, a Naval Signalman who served on Yamato,

recalls their enormous firepower.

KAZUSHI: The sound was very loud.

It felt as if many thunderbolts struck the ship all at once.

NARRATOR: But if Yamato had the most powerful guns on water,

why didn't it put up more of a fight?

NARRATOR: The drained wreck of the world's biggest battleship reveals

dramatic details of its final battle.

Scattered all around, hundreds of shell casings from Yamato's own guns.

But a closer look reveals they're not from its giant cannons.

Many of these casings are from a much smaller weapon.

Yamato's cannons are designed to destroy other battleships but are of little use against

fast moving attack aircraft.

It defends itself with much smaller 25-millimeter guns that fire shells

just over an inch in diameter.

But these guns have a problem.

ERIC: Unlike British and American capital ships, which were armed with

40-millimeter weapons,

the Japanese had nothing like that.

They moved straight from a five-inch anti-aircraft gun, to a 25-millimeter

anti-aircraft gun, and this made Yamato vulnerable to torpedo bomber attack.

It was a very mediocre weapon, slow elevation, slow rate of fire.

And it had a lot of vibrations, so it was very inaccurate.

NARRATOR: Yamato's underperforming anti-aircraft guns are no match for an

opponent she was never designed to fight.

Swarms of fast moving attack planes, carrying bombs and torpedoes,

launched from the latest US aircraft carriers.

Each of these holes marks a successful strike.

Enough to cripple Yamato.

But the drained remains of this sunken giant reveal another mystery.

Its 16-inch armor is shredded like tin foil,

and its massive hull is blown in half.

No bomb or torpedo could have done that.

Could it be that Yamato was ultimately destroyed by her own secret weapon?

Amongst the scattered debris lies the heart of the ship's fearsome firepower.

This hole is where the forward 18-inch gun turret used to sit and where shells and

propellant were stored in magazines before being fed to the cannons above.

-This is a potentially very vulnerable part of the ship.

If fire is introduced into the magazine,

it has the potential to destroy the entire ship.

NARRATOR: A clue to Yamato's fate comes from this rare footage.

It shows a torpedoed British World War II battleship, HMS Barham,

slowly sinking as it takes on water.

As the ship capsizes, shells begin to tumble from the magazine racks inside.

800 men die.

The drained wreck of Yamato shows how the blast that rips it apart starts here,

at exactly the position of the second magazine.

This is one of the last photographs ever taken of the super battleship.

Above it, a column of smoke rises three miles into the sky.

The result of that final catastrophic explosion.

-When Yamato blew up, there was a huge mushroom cloud, a preview of the mushroom clouds

that would very soon appear over Hiroshima and Nagasaki,

bringing the Pacific War to an end.

NARRATOR: Kazushi Hiro was assigned to another ship after his training on Yamato.

Now aged 94, he still prays for his many crew mates who died that day.

KAZUSHI: Dozens of the names of my friends are inscribed on this cenotaph.

I come here to visit their graves once a week since I have time and I'm alive.

NARRATOR: Japan's top-secret battleship was destined for the sea floor.

Not because of its kamikaze mission, but its secret weapons were rendered useless

by the changing nature of war.

-The sinking of the Yamato was the last gasp of the battleship.

It demonstrated that unless you had air cover, you were very vulnerable to torpedo

attack and therefore the age of the battleship was certainly coming to an end.

NARRATOR: The men who sacrifice themselves on board Yamato are inspired by an

astonishing event.

From the age of samurai warriors.

As the China Seas continue to drain away, extraordinary evidence emerges,

about an enduring maritime mystery.

How did the mightiest invasion fleet of ancient times vanish without a trace?

-It was one of the biggest disasters in the history of maritime warfare.

NARRATOR: Imari Bay, Kyushu.

The southernmost of Japan's four main islands.

700 years ago, warriors of the Mongol empire launch an invasion of Japan here.

Under orders from one of the most powerful leaders of all time...

Emperor Kublai Khan.

The Emperor is the grandson of Genghis Khan,

the legendary warrior who united the nomadic hordes of the Mongolian plains.

Now leading one of the largest armies in history, Kublai Khan continues

to expand the Mongol empire through China.

He establishes the city of Beijing and grows fantastically rich

from a vast trade network.

His power over life and death stretches from Europe to the China Seas.

But the Great Khan isn't satisfied.

-Kublai Khan was expanding the Mongol empire eastwards.

He made himself Emperor of China, he made Korea into a vassal state,

and now it was Japan's turn.

NARRATOR: Standing against the Khan are the samurai warlords of Japan.

And in 1281, he decides to reckon with them once and for all.

He constructs the largest fleet ever seen and sends it across the sea.

JAMES: Imagine what it must have felt like if you were a Japanese standing

on the shores there?

All of a sudden, what you're seeing is a wall of ships as far as your eye can see.

-The Mongol fleet was huge,

getting on for 4,000 vessels of various shapes and sizes.

It was probably the biggest amphibious operation before the

Normandy D-Day landings in 1944.

NARRATOR: The samurais fight bravely, and try to hold the line,

but are hopelessly outnumbered.

As the first wave of invaders battles on shore,

more are approaching from the sea.

But then, something astonishing happens.

The massive fleet of Mongol ships mysteriously vanishes.

-The loss of Kublai Khan's invasion fleet, getting on for 4,000 ships,

was one of the biggest disasters in the history of maritime warfare.

NARRATOR: So, what happened?

Japanese scribes credit divine intervention.

Historians, archaeologists, and divers scour the seabed and pore over the archives.

But fail to discover a single shipwreck.

Until now.

NARRATOR: Fascinated with the legend of Kublai Khan's fleet,

maritime archaeologist Kenzo Hayashida has spent years searching for it.

KENZO: I have committed myself to the survey since 1988, so for more than 30 years.

NARRATOR: Kenzo is inspired by an ancient Japanese record of the invasion.

It's only brought out on very rare occasions.

NARRATOR: The scroll clearly shows hand to hand combat.

And even the missing ships.

But it makes no mention of divine intervention plunging the fleet to the sea floor.

But under the waters of Imari Bay there are some clues.

A Mongol helmet, buckles, even an ancient comb.

And then, this.

A bronze seal inscribed with a date, 1277.

Struck just four years before the Mongol invasion and it carries the mark of a soldier,

a very important soldier.

IKUHIRO: It was an official seal of a company commander in the Mongolian army,

and the discovery became important evidence.

NARRATOR: It's the strongest proof yet of the Mongol invasion fleet.

JAMES: In terms of a smoking gun in archaeology, it doesn't get much better than that.

NARRATOR: Inspired by the find, Kenzo takes to the water.

Layers of thick mud make searching here very difficult.

But when he starts dredging the sea floor itself, he makes his first breakthrough.

-What we found were mostly goods carried on the ships.

For example, weapons, armor and pots to put food in.

NARRATOR: But still, where are all the ships?

Kenzo and his team need to find a way to peer even deeper into the mud.

And for that, they turn to technology.

NARRATOR: Based on this data,

draining the coast of southern Japan slowly reveals something spectacular.

First, some fragments of broken timbers.

But then, blowing away centuries of silt...

exposes the original seabed of 1281.

And there, resting on top of it, visible for the first time in 700 years,

the extraordinary tangled remains of Kublai Khan's lost invasion fleet.

NARRATOR: And the drained seabed reveals something else.

-And there, much like you would see from a crash site of an aircraft,

you see fragments of ships lying everywhere.

NARRATOR: Amongst the debris, weapons, pots,

even the bones of Mongol warriors.

-It's as if you took hundreds of ships and put them through a blender.

NARRATOR: What could wreak such havoc on an entire fleet?

Is this evidence of the divine intervention of samurai legend?

The answers lie in the thousands of wood fragments scattered across the seafloor.

Using the data from the sonar scan, like a giant 3D jigsaw puzzle,

it's possible to rebuild Kublai Khan's warships, and it's not what the

archaeologists expect.

Most of these ships were doomed before they even set sail.

ERIC: Kublai Khan had great problems mobilizing a fleet.

There were Korean vessels, but many of them were just coastal.

There were Chinese vessels, but many of them were just river craft.

They weren't very suitable for an oceanic invasion.

NARRATOR: Many of the ships lack one critical feature.

A deep keel.

Meaning they are unstable and easily swamped in rough seas.

What's more, they're poorly built.

NARRATOR: But shoddy construction doesn't account for the extent

of the devastation.

A clue to what happened lies 700 miles away, in Tokyo.

This is Japan's Meteorological Agency.

Its records only go back to the 1950s, but in that time,

a clear weather pattern has emerged.

HIROSHI: Japan is in the north west Pacific area, where typhoons develop most

frequently in the world.

NARRATOR: Each year, at least a dozen typhoons bear down on the Japanese coast.

One thing about the Mongol fleet is clear...

it arrives in late summer of 1281,

in time for typhoon season.

Where wind speeds can reach 190 miles per hour,

generating deadly waves 40 feet tall.

A wind the Japanese call, kamikaze.

JAMES: Kame for God, Kaze for wind,

creates a powerful legend of the Divine Wind that saved Japan,

or the kamikaze.

NARRATOR: Japan will evoke the Divine Wind

again on the brink of defeat in World War II.

It doesn't stop US forces then, but 700 years earlier,

the original kamikaze smashes

Kublai Khan's poorly built fleet to pieces.

-Most of the damage would be due to the typhoon.

NARRATOR: The greatest army of the age...

powerless in the face of nature's fury.

As the China Seas continue to drain away, the receding water reveals another

maritime mystery just off the coast of Vietnam, a vast jumble of shipwrecks

spanning 2,000 years.

What made this stretch of water one of the most dangerous in history?

And what extraordinary treasures lie buried on the sea floor?

IAN: First time in history, eyes are looking at this.

NARRATOR: The Cham Islands, off Vietnam.

Part of a region known as the coast that sank 1,000 ships.

Not the ships of fierce invaders, but ambitious traders.

Clues to centuries of bustling commerce are still found on the sea floor here.

For as long as anyone can remember, local divers have been making intriguing finds.

Porcelain and ceramics, hundreds of years old.

TRAN XA: According to archaeologists, the object is considered antique.

It belongs to around the 14th or 15th century.

NARRATOR: In local shops, recovered ceramics sell for hundreds of dollars apiece.

Where do these treasures come from?

And why are they strewn across the harbor floor?

A research team is scanning the harbor with the latest sonar technology.

IAN: If you go to a beautiful place like the Mediterranean,

you've got 40 meters visibility.

Here we can be down to half a meter so this time, the government has allowed us to

bring remote sensing equipment, and we're using side-scan sonar.

First time in history eyes are looking at this.

NARRATOR: Just minutes into the search, grainy images of what could be

wreck sites appear on the screen.

-Guys, come and have a look at this.

This is really interesting.

NARRATOR: The team dives for a closer look.

And in the gloom, a field of broken ceramics slowly emerges.

They scour a total area of four square miles and what they find is extraordinary.

-Ooh, hello baby.

NARRATOR: After careful analysis of the survey data...

it's now possible to drain the sea from the Cham Islands.

And remove layers of sand and mud to reveal an astounding sight.

A treasure trove of 15th century Chinese ceramics.

Cups, bowls, plates, still stacked in neat rows after 600 years.

Scattered all around are more wrecks, as many as 30.

-We're talking 2,000 odd years at least of wrecks that we'll actually have

under the surface here.

NARRATOR: Why so many wrecks?

And why so many loads of porcelain?

The answer lies in the Cham Islands' unique position,

at the eastern end of the world's greatest trade route,

the Maritime Silk Road.

Stretching from Asia to the Middle East through to Constantinople and Europe.

For 1,000 years, this oceanic superhighway connects princes and popes,

kingdoms and empires.

JAMES: It thrived because you had silks, you had spices, but you also had porcelain.

Chinese porcelains are beautiful, they're magnificent.

-It's simply down to the clays the Chinese had.

They had very, very white clays and it was unlike anything

anybody had seen before.

NARRATOR: The drained harbor of the Cham Islands

reveals yet more spectacular sights.

A United Nations of shipwrecks.

A Spanish galleon.

A Chinese junk, an Arabian dhow.

But why are so many ships wrecked in such a small area?

-I like to call this the parking lot theory because most car accidents

happen when you're trying to get in and out of the parking lot,

and the same thing holds true for harbors.

You have a cluster of ships trying to get in, get out, and if the wind changes,

you're blown right up onto the rocks of the beach.

NARRATOR: Drawn by the lure of porcelain and silk, the crews of these ships

all hoped to make their fortune.

But instead, they paid the ultimate price on this congested

and storm-lashed coast.

Today, the China Seas are still a major trade route,

but it's not porcelain that's transported across the seas, it's data.

What was once the Great Silk Highway, is now an Information Superhighway.

And just like the Maritime Silk Road,

this Data Highway is beset with dangers.

What are the deep-sea risks to the Worldwide Web?

GRAHAM: In this particular case, effectively it was a perfect storm.

NARRATOR: Our love of the internet knows no bounds, with demand for data doubling

every two years.

And the biggest gigabyte gluttons?

Social media and video.

Lots of video.

GRAHAM: Currently, there are four million views of YouTube videos per minute.

That is an enormous amount of data that's being consumed.

NARRATOR: Add to that the trillions of dollars in electronic funds

that shuttle between corporations and banks...

and it amounts to an astonishing 3.4 petabits of data that we gobble up,

every 60 seconds.

-And for those who don't know what a petabit is, ten to the 15 zeros.

NARRATOR: All that data has to be stored somewhere, which we call the cloud.

But data doesn't travel up into the sky.

It's actually transported deep below the sea.

Draining all the oceans reveals the million-mile network that connects

the Worldwide Web.

Where data shoots across the sea floor at the speed of light,

inside vast arteries of cables.

JAYNE: We talk about the cloud.

The reality is 98% of the internet runs over fiber optic cables under the ocean.

NARRATOR: One of the busiest and most important stretches of the internet

is here under the China Seas,

in the Luzon Strait, between Taiwan and the Philippines.

And like all undersea cables, this Data Superhighway is vulnerable to attack.

From the ocean's most fearsome predator, biting onto cables...

to entanglements with even bigger creatures.

This footage shows what happens when a humpback whale becomes wrapped in a loose

data cable off the coast of Norway.

The fire department manages to free the whale, but it means cutting the cable,

plunging parts of Scandinavia into an offline abyss.

To reduce the dangers, engineers take a course not open to ancient mariners,

burying precious cables deep below the seabed.

This delicate work is performed by a flotilla of specialized engineering ships,

which slowly unwind enormous drums of cable that will stretch for thousands of miles

across the oceans.

But the crucial work, happens deep below the waves.

Draining the water from above the ocean bed exposes the giant machines that

build the Worldwide Web.

A plough, the size of a house, crawls along the sea floor.

High pressure water jets help carve a trench ten feet deep and the

cable is buried inside it.

In the deepest parts of the ocean, far beyond the reach of anchors or even whales,

the engineers lay cables directly on the seabed.

Draining the deepest canyon of the Luzon Strait reveals the main data artery that connects

Asia and the West, 19 cables that shuttle trillions of gigabytes of

data between businesses, governments, universities, and stock markets,

all of them lying exposed and vulnerable.

Graham Evans is the Managing Director of a company that plans where

cables are threaded across the globe's oceans.

-It's not just a flat, featureless seabed.

Some of it is extremely rugged and we're having to maneuver around some of these features.

NARRATOR: His job is to find the shortest route from point A to point B.

But avoiding underwater obstacles mean that cables converge to what's

known as a Choke Point.

Like the Luzon Strait and its 19 cables linking east and west.

-Why is it a choke point?

There are no alternative routes when you're trying to go from Asia to the

United States, or Asia to Japan.

NARRATOR: On December 26, 2006, the choke point becomes choked.

-It was certainly a, a date that the industry won't forget.

NARRATOR: At 8:26 pm, a deep rumble shakes the seabed of the China Seas,

an earthquake with a magnitude of 7.1.

In Taiwan, buildings collapse, two people are killed, and dozens injured.

But that's not the end of the devastation.

In the deep canyon of the Luzon Strait, there's a second stage to the quake.

A massive underwater landslide.

-In this particular case, it was a, effectively it was a perfect storm.

There had been this huge build up of sediment at the head of this canyon,

and it didn't need much to trigger it.

NARRATOR: Directly in its path, the data cables on the canyon floor.

-So, if you're on the floor of the canyon, what you would see is this

billowing mass of black mud.

It pretty well took out every single cable that went between southeast Asia and

the United States.

NARRATOR: The internet shuts down and within minutes millions feel the

pain in their wallets.

-No submarine cables, no cash.

NARRATOR: ATMs stop working.

Stock trading halts.

Billions of dollars of transactions freeze.

Corporations and banks are paralyzed on both sides of the Pacific.

-In this particular case, there was never so many simultaneous cable breaks

that had such a devastating impact on the world's ability to use the internet.

NARRATOR: After some frantic work, data is rerouted via

other networks, eventually stemming the chaos.

But it takes three months to fully repair all the broken lines.

This cable crew and others like them,

will be busy for decades to come as the demand for data continues

to surge, driven by the booming economies of Asia.

To compete, or collaborate, trade or invade?

These twin human instincts continue to define the China Seas.

Draining the waters here reveals a turbulent past.

Exposes the truth behind a mysterious legend.

Celebrates the wonder of the Worldwide Web.

And whatever's to come in the next digital revolution.

Captioned by Cotter Captioning Services.