Original subtitles

Narrator: Hawaii, a paradise for sun seekers and surfers.

But hidden on this beautiful island there are scars from a day of infamy,

The attack on pearl harbor.

World war ii was fought on vast landscapes across the planet.

Marty (over radio): Where we're going, we don't need roads.

Narrator: But the evidence of that war is disappearing fast.

Pete: That is one of the coolest things I've ever seen in the water.

That's it...

Peter (over radio): Congratulations!

Narrator: Now, technology expert pete kelsey.

Pete: I've gotta scan this...

Narrator: And military historian marty morgan...

Marty: Oh my god, look at this view.

Narrator: Are using 21st century technology to strip away the present

And reveal the buried secrets of world war ii.

This time: Can a sunken seaplane reveal the secret

To japanese success at pearl harbor?

Pete uses the latest drone technology to unlock the mysteries...

Of a forgotten airfield.

Marty: Hey! Woah! Can't believe it! That's so cool!

Narrator: And one of america's most iconic battleships, is explored, scanned,

And revealed, as you've never seen her before.

(explosion)

(gunfire)

(explosion)

Marty: Few places that you can look at where history changed in an instant.

And this is one of them.

Because at 8:06 am on Sunday December 7th the history of the united states of america

Changed irrevocably with the destruction of the battleship arizona.

Narrator: The surprise japanese attack on pearl harbor

Lasted just a few hours and yet it devastated u.S. Forces.

21 ships of the u.S. Pacific fleet were sunk or damaged

And 188 aircraft destroyed.

It was the deadliest foreign attack on american soil to that date

And second only to the terrorist attack of 9/11.

So how did the japanese achieve such an overwhelming victory

Against the world's most powerful nations?

To find the answer, military historian marty morgan

And scanning expert pete kelsey have come here,

To the hawaiian island of oahu, scene of the attack,

Where they're setting up base for their investigation.

Marty: Nice, what's in here?

Pete: That's another drone.

Marty: How far will this one go?

Pete: That thing's amazing.

Narrator: Pete wants to see how the island itself shaped the battle.

So he pulls in data from satellites and aerial lidar

Scans to create a new 3d map of oahu.

Pete: This is cool.

Narrator: It reveals why this island became crucial to the us military...

An extraordinary natural lagoon protected by a narrow entrance.

Pearl harbor...

Pete: You can see that from orbit.

Marty: Yup. The u.S. Pacific fleet makes its home here starting in 1940.

This also reminds me that it's important to remember it's

Not just the pearl harbor navy base that's attacked on December 7th

It's all military installations across oahu.

So the u.S. Army had major posts at fort shafter and schofield barracks.

The army had airfields at places like hickam and bellows and wheeler.

So this is an extraordinarily well defended island and yet an attack still descends on it.

Pete: The whole place is one big military installation, a fortress.

Marty: The reality was oahu was a very well defended place.

Narrator: And yet the japanese not only caused a huge amount of damage,

They suffered very few casualties themselves.

The americans lost over 2,000 men, the japanese just 64.

How did they achieve this astonishing feat?

Pete and marty's mission, is to find out.

Crucial to the success of the attack was the element of surprise.

The huge japanese fleet had traveled over 3500 miles in complete secrecy,

An astonishing achievement.

But how much of a surprise was it really?

Did the americans miss a vital clue that would have given them a crucial warning?

One man believes they did, and he claims to have found the evidence to prove it,

He's submarine explorer terry kerby.

Marty: This thing is spectacular terry.

Terry: This is our baby.

Pisces 5 and her sister pisces 4.

Marty: How deep can they go?

Terry: 2,000 meters, 6,500 feet.

Marty: Is it possible to go inside?

Terry: Definitely. Let's check it out.

Marty: Nice, cool.

Narrator: Using his pisces submarines terry has been searching the waters around oahu

For the shattered wreckage of world war ii,

That still lies at the bottom of the ocean.

Terry: Pisces 5, pisces 4, go ahead over.

Man (over radio): Go ahead over.

Ok pisces 5 will be moving to the south, over and out.

Terry: Roger that. Ok, ok. Pisces 40 copy over.

Man (over radio): Copy over.

Narrator: And just here, 3 miles outside pearl harbor

He discovered something extraordinary.

Terry: So on that day I was in I was in pisces 4 and the other pilot was in pisces 5

And we had spent a couple of days doing searching.

Pisces 5. You copy.

Man (over radio): Yeah, we copy.

Terry: Yeah here we are coming across it.

Yeah. So that's pisces 5.

Marty: Oh my, it just comes up at you.

Terry: Yeah. Look at that.

And there it is. That's it.

Man (over radio): Roger, roger on the stand.

Marty: Can't believe it.

Terry: Moments in history.

So... That was a, that was a thrilling day and we were so excited.

I knew that was it!

Narrator: Terry had found a japanese mini-submarine,

Large enough to carry 2 people and armed with torpedoes.

But what is it doing here?

To find out marty looks into the u.S. Military records and he finds something intriguing.

Early morning on December 7th the warship uss ward is on routine patrol.

At 6:37 am it spots something in the water that looks like a small submarine.

The commander of the ward realizes it could be hostile

And so they fire at the sub using their 4 inch guns and drop depth charges.

Could this be the submarine that terry kerby has found?

To investigate, pete is going to create the first ever 3d scan of the craft.

He is taking high resolution images captured using a remote operated vehicle

And he's using a technique called photogrammetry to analyze them.

Pete: To start with it looks at every pixel in every image

And I've got thousands of them here.

It looks for patterns that enables it to actually stitch the photographs together.

You can see how the software has figured out the position where each photograph was

Taken and then you just begin to see a hint of the model that it's going to create

And then from there, this is where it gets really, really cool.

It actually creates a mesh, or model,

Of this minisub which is just an amazing piece of history and a piece of this story.

And of course the value here to figure out what happened.

You know how did she go down?

I mean look at that.

So terry I can't think of anyone I'd rather show this to.

Terry: Wow. That really is unbelievable.

It's unbelievable that you get this kind of detail, generate a 3-d image, from photos.

Pete: Does this do it justice?

Terry: Oh this is amazing.

Narrator: The first question is whether the minisub completed its mission.

And here the scan reveals the answer.

Marty: Look at those torpedoes.

Terry: Yeah. So these are the noses of the torpedoes.

Pete: Are they live?

Terry: Well, they have 780 pounds of explosive in each one

And nobody really wants to see how sensitive they might be.

Narrator: So the minisub never fired its weapons.

The real mystery is why this minisub is lying on the bottom of the ocean?

Pete: I am curious about something I saw when we were building this.

There is a hole.

Right here on the conning tower.

Narrator: Could this hole be the result of the shot from the ward?

Marty: The weapon that they fired at the submarine was a four inch 50 caliber gun.

It fired a 38 pound projectile traveling about 2,000 feet per second.

And if you look closely at the ruler you can see that there's been a little keyholing

So that the hole is a little bit bigger than four inches but the size is correct.

Pete: No one could have survived the impact of this round.

Narrator: So this is the japanese minisub spotted by the ward and fired on,

More than an hour before the main japanese attack on pearl harbor.

And pete's scan confirms that this hole was the result of that shot,

The first shot of the pacific war.

Fired not by the japanese, but by the americans.

Narrator: If the significance of the encounter with the minisub had been realized,

The americans would have had a valuable warning that the japanese were about to attack.

But instead, on the mainland, it was a sleepy Sunday morning.

No alarm was raised, they had no idea what was about to hit them.

Marty: Just after dawn on December 7th the japanese launched

The first wave of their attack.

183 aircraft that approach the island from the north sweep around to

The leeward coast of oahu and then begin attacking their targets.

Narrator: For the next hour the aircraft attack hawaii with impunity.

Despite the americans attempting to fight back,

Just 9 of those 183 planes are shot down.

Astonishingly, the japanese carrier fleet, around 250 miles north of oahu,

Doesn't take a single hit.

Why do the americans do so little damage to the enemy?

The answer could lie with a unique airplane: The pby catalina.

The catalina is a seaplane with an exceptional range,

It can fly over 2000 miles.

So it's used as a reconnaissance aircraft,

Able to search the seas and find enemy ships.

It was the catalina's job to locate the attacking fleet but that fleet was never found.

To find out why marty and pete have come to the eastern side of the island, kaneohe bay.

The pby catalina takes off from the water,

So this sheltered bay was the perfect home for 3 squadrons of catalinas.

Marine archaeologist hans van tilburg has been studying the history

Of this unique airplane.

Hans: This was a great step forward,

A mono wing seaplane with an immense range and endurance.

And it just became a real work horse.

Crew of 9.

It had the capability to drop bombs,

It could also land on the ocean and rescue a lot of downed pilots.

It really became known for the long range search and patrol missions.

Marty: I get distracted sometimes into admiring the pby because

It's an elegant and beautiful aircraft.

And it makes me lose track of the fact that this was

An important weapon of war as well.

Hans: That's right.

Narrator: So why didn't the seaplanes moored here take

To the air and track down the japanese fleet?

Hans has discovered the sunken remains of a catalina.

Perhaps that can reveal the answer?

First they need to use sonar to pinpoint its location.

Ron: So what's the wingspan?

Hans: This things have over 100 feet, a giant parasol wing.

Ron: Oh really? Wow.

Hans: That's why they stayed aloft and had a range of 2500 miles.

See that.

Ron: Yeah we got some hits here.

There it is. There it is.

Looks like the fuselage.

Pete: That's gonna be a wing.

Ron: That's our spot. 50 feet away.

Ron: 41. Hans: Stay on target.

Ron: 32. Hans: Stay on target.

Ron: 24. 21. We're over it.

Narrator: This bay is known to have very poor visibility,

Which makes it impossible to get a good view of the wreck.

So pete and his dive team are going to use 3d scanning,

To reveal the catalina as never before,

And hopefully find out why it's lying at the bottom of the bay.

Pete: The mission here is really, as these cameras suggest,

It's all about photogrammetry.

So we are going to do our best to basically just orbit, take pictures as we go.

As many pictures as we can because we want lots of overlap between pictures and

Just get as much coverage as we can with the cameras.

Narrator: Pete is searching for the wrecked seaplane.

At first he can see nothing.

But finally a structure appears through the murk.

Hans: This looks like fuselage moving in.

Torn bits of aluminum.

Marty: That lack of visibility is really obvious here.

Hans: I think it'll be hard to patch this together.

Narrator: The silt makes this is an incredibly challenging environment for photogrammetry,

Each photo can only capture a small part of the huge structure,

Which means they'll need thousands of pictures.

And every movement they make, risks disturbing the bottom

Reducing the visibility even further.

Hans: We won't know if there's enough to model it until we try to put it together.

Pete: Good stuff. That is a cool airplane.

The visibility is not great.

It might be five feet maybe a little less.

And you really, really have to be careful with your movements because one wrong flick of

Your hand or especially one of your fins and you're gone

Because the silt is just everywhere.

So... Challenging but not impossible.

Narrator: Can pete turn these murky images into a 3d model

And find out what happened to the catalina?

Narrator: It takes more than 8 hours of processing,

To turn the thousands of photographs

Into the first ever 3d scan of the catalina wreck.

Pete: Hans look at the mesh.

Hans: Oh nice. This is amazing to see it like this

And not be hanging upside down in kaneohe bay is fantastic.

Narrator: The scan clearly shows one of the huge catalina wings.

The fuselage, or body, is tipped on its side.

The other wing and parts of the tail section are missing.

Pete: With the visibility and the water being what it is you can't see the whole thing.

Hans: You cannot.

This is a 3d vision of the site that is impossible to have today.

Nobody can see the aircraft like this, as only on the bottom of the bay.

Pete: Is that cockpit?

Narrator: Inside the cockpit pete notices an astonishing detail...

These are the throttle levers, one for each engine.

And on the scan you can clearly see that one of the throttles is pushed forwards.

Hans: The port throttle is in the starting position which suggests

That someone may have been starting the port engine.

Narrator: And there's another clue,

The catalina is equipped with floats, or pontoons,

That stabilize the plane when it's on the water.

In-flight the floats pivot and become part of the wing.

So what condition is this plane in?

Hans: This is the retractable wing tip pontoon.

Pete: And so these are in the lowered position.

Hans: Exactly.

Narrator: So the pontoon is a clue that this plane wasn't yet in the air even though

At least one of its engines was running.

Hans: That tells us that this aircraft was at its mooring.

On the water. It exploded and sank...

Pete: So somebody, somebody is trying to get the thing out of there

Because you're under attack.

Hans: Absolutely. This was a surprise attack.

Narrator: Pete's scans reveal that this catalina was still on the water apparently

Preparing to take off, but it was struck by the japanese

Before it could get airborne.

And this plane wasn't the only one damaged.

On land there's evidence of just how devastating this attack was.

Today this is marine corps base hawaii, a highly restricted military facility.

But pete and marty have been given special clearance to look

For traces of December 7th.

Marty: The tarmac here at kaneohe is still being used today.

This tarmac was here in December 1941 except back then there weren't

Huey helicopters parked here.

There were catalinas, 36 of them in all.

They were tied down some of them outside of the hangars

On hard stand at tie downs like that.

Some of them were inside hangars in fact, some were in the water.

And these aircraft were targeted by japanese aircraft.

Japanese came in strafing them with machine guns and then dive bombers

And then level bombers dropping bombs on them.

And at one point one bomb landed right here.

Narrator: A 3d scan reveals not just the crater itself.

Now filled in with concrete.

But scars from the fragments of shrapnel that splayed out from the impact.

Marty: Yet another piece of evidence from the December 7th attack

That is still with us today.

Narrator: Some of the catalinas were stored indoors in these hangars.

Pete wants to see if he can find evidence of the attack there too.

And in the stairwell at the back he discovers something fascinating.

Pete: Oh yeah. So this is hangar one.

And rumor has it that there's damage in here from December 7th 1941.

Interesting angles in here but really no problem for the scanner because the laser goes

Out in all directions at about two million times per second.

The laser scanner loves interiors.

So we'll get really rich photo realistic three dimensional data

Of everything in this space.

So 10 minutes from now we're going to have some really amazing three dimensional data.

Narrator: The 3d scan reveals that the metal staircase still has bullet holes from 1941.

These must have come from japanese aircraft firing machine guns at the hangars.

Pete: Look at this. So that's either.

Because the shape's little odd it's either a round that struck somewhere else and

Tumbled into it.

Or maybe a bit of shrapnel.

And there's one here.

Looks like that.

And another one right there.

That sort of sends a chill up your spine right.

Not even indoors are you safe.

So even in this concrete stairwell, bullets are flying and you can tell

That this is the entry side.

So the bullets would've been coming in this direction.

That's just, just amazing.

Narrator: So the japanese attacked the base with bombs and bullets.

It was a devastatingly successful raid.

All 33 of the catalinas on the ground or in the water were damaged, many beyond repair.

There was now no way for the americans to find the japanese fleet.

But that didn't mean they couldn't fight back.

The americans had more than 150 fighter aircraft stationed at airfields around oahu

Ready to protect the island.

But the japanese were prepared.

At the same time as they destroyed the catalinas,

They also attacked these airfields.

The result was devastating.

Narrator: The japanese plan was to first take out the island's air defenses,

Even before the more famous attack on pearl harbor itself.

Today, most of the visible evidence of that attack is lost.

But pete and marty are hoping to find traces in one hawaii's forgotten airfields,

Southwest of pearl harbor in a place called ewa.

It's visible on the lidar scan.

If you strip away the vegetation you can still make out what looks like a runway.

Marty: People don't get to come here, it's a little bit off limits.

Pete: This obviously looks like tarmac to me.

I mean runway or a parking ramp or something.

This is definitely an airfield. Wow.

Marty: What do you think?

Pete: Well I think it's big.

So this must have been airplanes everywhere.

Marty: I'd say you've got a couple of layers of history all superimposed over one another.

Narrator: This airfield was home to nearly 50 planes on December 7th,

Including fighters and bombers.

There don't appear to be any visible traces of battle but pete thinks he might be able

To find some using a bit of airpower of his own.

Marty: Whoa. What all is in here, pete?

Pete: So, tripods for the g.P.S., landing pads.

Some pretty important stuff.

Marty: So where do you put the rockets and the machine guns?

So what benefit does a drone of this size and complexity give you

That the smaller drones don't?

Pete: Coverage because it can transition from hover to fixed wing

And when it does you will see it take off.

Narrator: Pete wants to get a scan of the large concrete area where aircraft were kept.

Marty: Pete that was so cool.

Narrator: He's hoping that his 21st century tech will detect long lost scars of battle.

Pete: It should transition. It is.

Marty: What?! That was cool.

Narrator: It's equipped with a multi spectral camera.

That takes images in five different wavelengths.

Three visible colors and two infrared bands that the human eye can't see.

Marty: The coolest pete.

Pete: See it yaw into the wind.

It is trying so hard to stay on a straight line.

Narrator: The drone flies autonomously on a pre-programmed path.

So that every inch of the target area is covered.

Pete: Now it's in the lane, it's going to come this way.

Marty: Oh there it is. It's just getting it done, isn't he?

Pete: Yup. Turn baby, turn.

All right. I'm hitting return to land.

Marty: Will it put down on that pad?

Pete: It will.

Marty: Damn it straight up above it, isn't it?

I can't believe it.

You kidding me? Pete, that was so cool.

Pete: Okay, you're clear. Disarmed and just in time.

Narrator: Pete has captured thousands of images of the airfield at ewa.

Next he uses image processing software to stitch them together

And create one super high resolution image.

And here in the corner of the large concrete area.

Something has caught pete's eye.

Pete: There's a spot it should be right here.

In the data there's this like big sort of scar...

Marty: Oh it's right here, isn't it? Pete: Right here.

Marty: Yeah. That's from high heat.

And so otherwise you'd just walk right over it and not even notice it.

But this is basically the footprint of a burned aircraft.

Pete: So a parked aircraft...

Marty: Here's an eyelet you see.

There's a tie down so this was a hard stand.

So you had a marine airplane that was tied down right at this spot.

It was struck.

As the fuel inside the aircraft burned off,

As the airplane turned into a torch...

And it left this damage that's still here to this day.

Pete: Right and militarily neutralizing your opponent's airpower which was lined up

And exposed right here makes sense.

Narrator: Every single one of the 49 aircraft at ewa was disabled by japanese fighters.

And across the island the japanese would go on to damage

Or destroy almost 350 of the 390 us aircraft.

The strategy had worked.

Us air defenses had been devastated, their eyes and teeth neutralized.

Now the japanese could turn to their main target...

Pearl harbor.

It's here that the deadliest event of that day occurs.

Pete's next task will be to reveal the site of that most infamous tragedy,

As never before...

Pete: Unbelievable!

Marty: The next step in the japanese first wave is the attack on the navy base here

At pearl harbor and it begins at about 7:55 am,

They had expected to find aircraft carriers but they didn't find any.

And so they focused much of their attack on this, the eastern side of ford island.

Narrator: The japanese prime target is now the 7 battleships moored up

In a line called battleship row.

They attack first with torpedo bombers, flying as low as 50 feet.

The battleships oklahoma, west virginia, and california

Are all hit by these 800 kilogram torpedoes.

Then the high-level bombers attack,

Dropping armor piercing shells from around 10,000 feet.

And then, 15 minutes into the attack,

The japanese score their most devastating hit,

On the battleship arizona,

Caught on film in this extraordinary footage.

♪ ♪

The destruction of the arizona causes the largest loss of life that day.

1,177 men are killed,

More than died on all the other ships put together.

Marty: Arizona up until that moment up until 8:06 am was this magnificent piece of

National prestige the pride of the navy literally.

You can still see her. She's still here.

The buoy there marks the bow of the ship and there's another buoy

Back here that marks the stern 608 feet long.

Beautiful, beautiful ship.

Narrator: Now, this mighty battleship is preserved as a memorial,

Under the custody of the national park service.

And today pete is going to join park service divers as they scan the wreck.

Pete: I never get tired of this ever.

This is one of the greatest things I get to do.

Just to be here.

But to actually contribute to some of the actual hard work and the science is just

Incredibly meaningful to anyone who is here and gets to get in the water.

Narrator: Pete is hoping the data he collects will show why the arizona suffered

So much more damage than any other ship.

The first phase of pete's investigation is to create a new 3-d model

Of the exposed upper deck of the ship.

Pete (over radio): We're here at the uss arizona.

How can you not just be amazed by a site like this?

These are bowls that sailors no doubt ate out of.

Beautiful white hexagonal tiles here in the area of the galley.

Here we actually might have what could be a bomb penetration hole.

The bomb came through the deck.

You have the skin of the ship.

You can see it curves as it exploded.

A site like this is a great place where we can use photogrammetry to monitor

The change that's obviously going on here.

So we will swim around this site with a camera taking pictures as we go.

You can literally fly.

Here's an open hatch.

I'll have a go at it.

With the right camera you can get not only beautiful models

But important models, valuable models.

Oh my gosh.

Looks like a leather boot of a sailor.

That's just astonishing.

It really puts the humanity on the arizona.

Everything about this,

Paying the ultimate sacrifice.

Narrator: Will pete's scan reveal what happened on that tragic day in 1941?

Narrator: Pete and his team have taken thousands of images

Of the exposed top level of the arizona,

Focusing on an area in the middle of the ship, here.

Next, pete can turn them into a brand new 3d model which reveals

An extraordinary window into life on board the ship.

He's going to analyze it with national park service historian, and arizona expert,

Daniel martinez.

Daniel: God the detail is amazing.

You know I've had the opportunity years ago to dive on it

And now I'm looking at detail that I would think would be unthinkable at the time.

Narrator: These details reveal exactly which part of the ship we're looking at.

These are huge ovens, meaning that this is the galley,

Where food was prepared for the crew.

You can even see the kitchen tiles.

It's a reminder that this was where hundreds of sailors worked, slept and ate.

Including many who lost their lives in the attack.

Pete: A great surprise to me, there were all these artifacts that

Absolutely put people on the ship.

There were shoes, bottles, a cooking pot,

And it's just really personal.

The project pretty much changed for me in that moment

When you see artifacts that...

Daniel: Are connected to human beings...

Pete: Right.

Daniel: Well that human touch just reminds you that this was a living ship.

It brings it all home, this great tragedy of the outbreak of world war ii

For the united states of america.

We're very fortunate the arizona is in the pearl harbor naval base

Because that ensures its protection.

And so, that there won't be people that would do something they shouldn't do,

And remove something from the ship.

Because everything on that ship, is a clue to what happened.

Narrator: But to figure out what caused so much damage to the arizona,

Pete is going need more than just a scan of this one area,

He needs the whole ship,

Which is impossible just using photogrammetry.

So he's used a combination of sonar,

Underwater laser scanning and robotic surface vehicles

To create the highest resolution scan ever of the uss arizona.

And using augmented reality the whole of the mighty arizona can be seen,

For the first time in more than 75 years.

Pete: Wow!

So this is perhaps the greatest representation

Of the scan data we did of the ship.

I can't get over it.

All 600 feet of this ship.

Starting right here at the prow.

And it goes all the way up. And out.

And 600 feet that way about 100 feet wide.

Unbelievable. I mean look at this.

Oh my gosh.

Narrator: This scan reveals that the front of the ship has been blasted

Open by a huge explosion.

Pete: So no doubt when the explosion happened.

This is such a great view of how the battleship armor plate just flowered out

From this massive explosion.

Narrator: This model shows the damage to the arizona as never before.

The force required to cause this much destruction is greater than any bomb carried

By the japanese aircraft.

But the pattern of damage shows that the explosion

Occurred in this area of the ship.

And this is the location of the magazines,

Where explosives and armaments were stored.

So a japanese bomb from a high level bomber must have penetrated the ship and

Ignited these munitions.

This produced a terrible explosion, caught on this remarkable film,

Leading to the rapid sinking and huge loss of life.

Marty: And now since 1961 this beautiful memorial,

Which was built over the wreck of the ship,

Has stood here in memory of the 1,177 men who lost their lives on it when it exploded.

And the over 900 men who remain inside this ship to this very day.

Which is I think why this has become such a special place.

Because world war ii only began at the moment that their lives were lost.

Narrator: Pete and marty have revealed the secret scars of that day of infamy,

Still here after more than three quarters of a century.

These traces have shown just how brilliantly the japanese executed their plan.

But america then responded with a ferocity and determination that

The japanese didn't expect.

For all its apparent success, the attack on pearl harbor

Would turn out to be a disaster for the empire of japan.

Captioned by cotter captioning services.