Original subtitles

[dramatic music]

- Tonight, one of the most legendary disasters in history.

[foghorn blares]

- When we talk about Titanic,

we're talking about the largest

manmade moving object of her time.

- Literally hundreds of people shouting for help

in the water in the darkness.

- Questions persist around what really happened

that fateful night and why.

- Was it just the iceberg

or did other things happen that led to it?

- Whose decision was it to travel faster?

- Titanic did suffer a large bunker fire

that began in Belfast.

- Now we explore the top theories

behind this iconic ship's tragic end.

- They're basically looking for a shadow in the dark.

- No one knew that these photos existed,

but they may reveal something about Titanic

that we never knew before.

- Can new evidence reveal more about how

and why the Titanic sank?

[dramatic music]

- [Laurence] On April 10th, 1912,

the Titanic set sail from the English port of Southampton

on its maiden voyage to New York.

This is the golden age of ship travel

and Titanic is the era's crown jewel.

- Titanic, to put it lightly, massive.

It's as long as four city blocks.

It is 17 stories tall.

It is as wide as a four-lane highway.

- She is a hundred feet longer

and thousands of tons heavier than any ship ever built

- [Laurence] On board,

Titanic is carrying just over 2200 people,

1,316 passengers, and 885 crew members.

- If you're a first class passenger,

you had access to things like a squash court, ballrooms,

Turkish bath.

This is the ship

that has a first ever swimming pool aboard it,

four different restaurants,

everything ranging from a Parisian cafe to a dining saloon

that could hold about 500 people in it.

- As passengers walk on board,

they're greeted with a large grand staircase,

which would be something one

would see in a great hotel

rather than onboard a ship.

- Second and third class passengers

don't have as much access to these amenities

as first class does.

However, there is running water in every single cabin

in the ship, which is a huge luxury.

- [Laurence] But it's below the passenger decks

where we find the Titanic's technological wonders.

- The Titanic is full of advanced technological features

from 30-foot tall steam engines that power the propellers

to advanced safety features

including remote controlled watertight compartments.

- If the ship had a collision,

the watertight doors could be closed

and only that compartment would fill with water.

The other compartments would be safe

and the ship would continue to float.

[telegraph tapping]

- Titanic also has a very modern thing,

which is a wireless set

so she can communicate several hundred miles

with other ships and also to land.

This was really the beginning of the modern radio.

- [Laurence] The ship is so technologically advanced

that its owner and operator, the White Star Line

is confident enough to make a bold claim.

- The Titanic, the unsinkable ship,

God himself will not be able to sink this ship.

- [Laurence] On the evening of April 14th,

the Titanic is cruising through the North Atlantic,

about two and a half days away from New York.

- The sea was completely calm like a mirror.

The stars were setting right down to the horizon.

In fact, some of the passengers said

that they could see the stars reflected

on the surface of the water.

- [Laurence] Then just before 11:40 PM

something ominous emerges from the dark.

- Titanic's lookouts are staring ahead at the calm ocean

and then they notice a dark object

coming out of the haze in front of them

and they ring the bell three times

to indicate to the bridge

there's an object dead ahead.

In charge of Titanic that night is First Officer Murdoch.

He is the first officer on the bridge

also staring ahead with his binoculars.

As soon as they hear the warning of the bells,

Murdoch gives the order harder starboard to turn the ship

to the left hand side

and immediately Titanic slowly starts to turn.

- [Laurence] And then just 37 seconds

after the iceberg is first spotted,

Titanic makes contact.

[hard impact and metal grinding]

- She misses the berg that she can see above the surface,

but unfortunately a spur of the berg under the water

scrapes along Titanic's hull.

The impact of the iceberg is in fact so slight

that most passengers sleep through it

and some who were already awake

just regard it as a small bump.

[water gushing]

- [Laurence] But it's much more than a small bump.

- Immediately Murdoch knows he had hit an iceberg.

He orders the watertight compartments to be sealed

and the watertight doors to be lowered.

- [Laurence] But the water continues to pour into the ship

and five minutes later, Titanic's engines shut down.

At 12:05, 25 minutes after hitting the iceberg,

Captain Smith orders the first lifeboats

to be prepared for launch.

- They're very well aware

that they do not have enough lifeboats for everyone

and there had been no lifeboat drills.

There was no way to really get the proper information out

to the passengers in a way

that would facilitate a orderly evacuation of the ship

without incurring panic.

Here you are in the middle of the ocean.

It's freezing cold out.

You're on this enormous ship.

You gotta have a leap of faith to get in a very small boat

and leave that ship.

- People are scrambling

and panicking all across the deck

as the final lifeboat is about to depart.

They're realizing that there is no other means of escape

at this point.

- The bow is now moved deeper and deeper into the water

and slowly we begin to see the stern

or the back of the ship come up out of the water.

- At about 2:18 AM the front of the ship,

because it's full of so much water

is dipping in underneath the surface.

The pressure of all the water from the front

mixed with the weight of the propellers in the back

causes the ship to snap in half.

[dramatic music]

- After Titanic breaks in half,

her stern comes right up into almost vertical position

and then slowly slips beneath the waves.

On the surface there is panic.

There are lifeboats rowing away from the scene

to avoid suction and now there are 1,500 people

in the water in the darkness.

- [Laurence] Rescue ship Carpathia

reaches Titanic's coordinates

at 3:30 AM only to miss the sinking ship

by a little more than an hour.

They rescue 706 survivors from the lifeboats.

Two thirds of Titanic's passengers and crew are gone.

News of the sinking makes headlines around the world.

- There's no doubt that the ship struck an iceberg.

What everyone wants to know

is how this seemingly unsinkable ship could suddenly sink

beneath the Atlantic within three short hours.

- [Laurence] Within days of the tragedy,

the US Senate launches an inquiry to answer that question.

A parallel investigation soon follows in Great Britain.

- Both investigations

are looking at one potential contributing factor

to the sinking of Titanic,

which is the speed at which the boat was traveling.

- The Titanic's projected rate of speed

for the voyage was 18 knots.

Yet the inquiry finds that it entered the iceberg field

operating at 23 knots,

which then leads to the question,

whose decision was it to travel faster?

Captains often do something that's called banking time,

which means when conditions are good,

they'll travel faster

so they can either arrive ahead of schedule

or be ahead of schedule in case of inclement weather

that might make them slow down and use more caution.

- Until Sunday night, Titanic was ahead of schedule.

They had no problem with weather, no problem with fog.

The ocean was calm, everything was going their way.

- [Laurence] Despite these perfect conditions,

Titanic received six messages

from other ships warning of icebergs ahead.

- But despite all of these warnings, again,

'cause it was nice weather,

because the ocean ocean was calm,

Titanic decided to just steam straight ahead

at the same speed that they were maintaining

for the majority of the trip.

- [Laurence] As investigators question

why the Titanic didn't avoid the iceberg,

one answer seems to be speed.

[dramatic music]

Soon the managing director of the White Star Line,

Bruce Ismay, finds himself under scrutiny.

Ismay was a passenger on the Titanic and survived.

- Ismay is this incredibly wealthy

and influential businessman that wants to dominate

in the shipping market in England,

and so that's why he builds Titanic.

The problem with Ismay

is that he's also incredibly ambitious.

- One of the things that comes out in the inquiry

is that one of the first class passengers

actually overheard Bruce Ismay urging Captain Smith

to put on all possible boilers

to arrive in New York a day early.

Ismay also boasted to the first class passengers

that they were planning on arriving in New York a day early

to make a big splash.

- [Laurence] When it's Ismay's turn to testify,

he insists that he never

specifically ordered Captain Smith

to speed up.

- Ismay's response to these claims

is that he sees no reason

why commander should not go full speed

provided he can see ice in time to avoid it.

- Public sentiment is not very kind towards Ismay

for that statement,

but it's also not kind towards him

because it's later found out that he jumped into a lifeboat

and left women and children behind on the deck

of the Titanic as it sank.

- This caused the public really to blame Bruce Ismay

for the excessive speed of the Titanic.

Ismay himself did actually say

that he regretted surviving the Titanic disaster.

- The Senate investigation concluded

that Captain Smith was moving at high speeds

through the ice fields

and that was a contributing factor

to the sinking of the ship.

The British inquiry thought

that this was merely a freak accident

that captains can maneuver ships all the time at full speed

through ice fields after ice warnings.

And so Ismay and the captain were essentially absolved

of any guilt.

- But as historians study Titanic more and more,

they start to notice that there might be more to the story

than what originally appears.

- Despite all the factors from the inquiry

and what historians and archaeologists have studied

over the years, the question still remains,

if the ship was that massive, and that unsinkable,

and that technologically advanced,

could an iceberg really be the root cause

of the ship sinking?

- [Laurence] Both the US and British inquiries

blamed the Titanic's sinking on the ship's high speed

in the face of numerous iceberg warnings.

Even so, questions remain.

- The night of the 14th of April, 1912 is totally clear.

The water is calm, the stars are bright.

The stars are even setting down to the horizon.

- [Laurence] But in this area,

even perfectly clear weather can be deadly.

- There's no moon up at the time.

The moon phase was such that it was coming up much later

in the morning and so it's dark.

It was very dark.

- The meteorological records of the time

and also from log books of other ships in the area show us

the Titanic sank in this very cold part of the Atlantic

called the Labrador current.

The Labrador current carries icebergs

that originate in Baffin Bay

and then they come all the way around Newfoundland

and then they come down what's known as Iceberg Alley,

where they then mix into the much warmer Gulf Stream

and it's sending these really large bergs deep

into the North Atlantic.

- The last few winters had been fairly mild

and this actually creates more icebergs

'cause there's melting and there's fractures

and the ice falls off these ice sheets

and falls into the ocean.

- The tip of the iceberg that you can see above the water

is a small fraction of this enormous block of ice

that's huge like a sail under the water

and it's being dragged along by the Labrador current

and it's bringing these enormous icebergs much further south

than normal into the Gulf Stream.

- Normally in a typical year,

you'd see around 125 icebergs in this area,

but in 1912, specifically around April of 1912,

they saw around 400 icebergs,

which was the most that they had seen in about 50 years.

- Seven minutes of steaming time beyond

where Titanic collided,

there is a barrier of ice that's three miles wide

and 30 miles long,

and in fact, this barrier of field ice is suppressing

the swell in the North Atlantic

and it's cutting off the waves.

It's extremely rare to have conditions

that calm on the North Atlantic.

Normally where you have ice mixing with the warmer water

of the Gulf Stream, you get fogs.

But that night they had an area of very, very high pressure

and that was keeping the air crystal clear.

- [Laurence] The night is almost too clear

and that makes the crew very wary.

- Reginald Lee, who was on the crow's nest said,

"A clear starry night overhead,

but at the time of the accident

there was a haze extending more or less round the horizon.

It was a dark mass that came through that haze."

- The iceberg that sinks the Titanic

is pretty large in scale.

It's 50 to a hundred feet tall and 400 feet long.

So you would think seeing this object,

you would notice it coming from miles away.

So what happened that night

that the crew almost missed it entirely?

[dramatic music]

- Early in the evening, the officer of the ship

starts to realize that we have dropping

both seawater temperatures and air temperatures,

and this suggests the presence of ice.

You can't see it perhaps, but you know it's out there.

- The electric lights on the Titanic started forming frost

on the outside of them,

so they started to look like little ice crystals basically,

that's how cold it had suddenly gotten.

- As the ship is approaching ice,

we're getting the situation where we're,

we have a separation

of layers of air

and so near the surface of the water, near the ice,

the air is rather cold,

warmer air rises above and you get a layered effect

and then you do get some flow of air between them.

- When you have cold air and warm air meet,

it forms a kind of lens,

and that lens, what it can do is it can bend light around it

and create images that might not actually be there.

- It was behaving in the opposite way to a desert mirage.

In a desert, you have a very hot surface

and the light actually bends slightly upwards

and that brings the sky onto the ground

and that's why people in the desert think,

oh, there's water over there, when there actually isn't.

But the Titanic was so cold where it sank

that in fact the light was bending downwards

around the curvature of the earth

and this was raising the horizon upwards,

which appeared as a haze all around the horizon

caused by the molecular scattering of light

and the depth of air that you can see through.

- This haze, sometimes it's referred to as the fata bromosa,

a fairy fog.

If you've ever been fishing on a lake early in the morning,

you're gonna see a haze across the top of the water.

Most of us think of mirage as a false image

and it's not a false image,

it was just a hindrance to seeing the iceberg.

- The haze around the horizon was the same color

as the berg,

so instead of seeing the white iceberg

against the dark night,

they're seeing the white iceberg against a white mist.

- Captain Smith is well aware of the situation.

At one point before he retires, he mentions to the officers

that if any haze was observed at all,

no matter how slight, he should be awakened.

That never happened.

- [Laurence] Adding to the confusion that night,

the lookouts weren't using binoculars.

- There were binoculars on the Titanic,

they were stashed away in a locker.

Problem was the one crew member that had the key

to the locker had been reassigned to another ship

at the last minute so no one could access the locker,

open it up and get ahold of those binoculars.

Had they had the binoculars,

it is possible that that magnification

could have been used

to cut through that optical illusion

and had them see the iceberg far enough in advance

so that they could have made their way around.

- [Laurence] But not everyone agrees

that binoculars would've helped.

- Binoculars were for inspecting an object

that you'd already detected

and in fact the best way to spot ice at night

is with the naked eye

because it gives you a broad field of vision.

The officers had binoculars, by the way,

because their job was to inspect what the lookouts detected,

so at the detection end you don't need binoculars.

Had Titanic's lookouts had binoculars,

it would've narrowed their field of vision

and they may have picked up the iceberg later.

- In 1909, construction begins on the Titanic

in Belfast, Ireland.

It's designed to be not only the most lavish ship

on the seas, but one of the safest.

- Titanic's construction starts in 1909

and its design specifically had safety features

that were new and innovative for the time period,

which really led to the media calling her unsinkable.

- Titanic's builders and her owner

boast on the maiden voyage

that Titanic can be sliced crosswise

into three separate pieces and each individual piece

will float.

- Part of the design of the Titanic was to allow it

to be a massive lifeboat in the event that damage occurred,

they could shut the four compartments

or however many compartments had been punctured

and eventually the passengers

could be rescued within that time.

- However, historians contend

that there was one small mistake

with the design of the ship.

[dramatic music]

- Titanic is a massive 800-foot-plus long ship

separated by steel walls known as bulkheads.

Those walls separated the watertight compartments

in the ship by which there were 16, close to double

the number of water tank compartments

or compartments that you'd see in your typical ship.

- If you've ever walked through a submarine,

you have a door that you have to hunker down

and walk through and then they can close that door.

That's a bulkhead.

The same type of bulkhead that was on Titanic.

- The bulkhead has two purposes.

One, to contain any water

that might make it into the ship in case of a puncture

and to actually strengthen the hull.

- It's engineered such that if the ship

were to be hit in one of those watertight compartments,

they could close the doors on either side of it

and only that compartment will fill with water.

Worst case scenario, if it hits on a bulkhead wall,

it would fill two watertight compartments.

Titanic is so special

that if any of the first four watertight compartments

or all four are compromised, the ship would still float.

- [Laurence] But there's one critical weakness

in the design.

- Titanic's watertight bulkheads were not carried

all the way up and they were not capped by a watertight deck

because that would've interfered

with crew and passengers being able to move about the ship

and also it would've interfered with cargo loading.

- They didn't want to ruin the design

and the experience for the passengers

by placing the bulkhead walls all the way up

through the deck,

that means that at any point if one compartment floods

and it goes above the waterline and above the bulkhead,

it can flow into the next compartment.

- [Laurence] On the night of April 14th, 1912,

the bulkheads are put to the test.

[hard impact and metal grinding]

- Titanic hits the iceberg,

it scrapes across the right side of the ship, opens it up,

water starts rushing into the front compartments.

The watertight doors are shut,

but water starts flowing into the other compartments

that are not protected by those bulkheads.

The squash courts, the mail room,

and even the boiler rooms

are starting to fill up with water.

- There is water pouring in the side of the ship

and Thomas Andrews,

the ship's designer,

goes down and sees all the water coming in.

- Because of Andrew's familiarity with the Titanic,

he's able to tell from the moment of impact

until that moment how much water has come into the ship.

He's able to take that water flow rate

and calculate how long it will take

to fill the four bulkheads

and then he notices

that it's in watertight compartment number five,

and that the pumps aren't handling it.

That's when he comes to the conclusion

that the ship is going to founder.

- [Laurence] According to survivors,

approximately 45 minutes after the collision,

Andrews informs the captain

that the first five compartments are now flooded.

- The captain and the designer then proceed down

to the engine room to talk to the chief engineer

to try to figure out what can be done and what can be saved.

- As water flowed into the forward compartments of Titanic

that were damaged by the iceberg,

this weight of water caused the bow to dip down.

And of course,

because the bulkheads didn't have a watertight deck

on the top,

it meant that water spilled over from one bulkhead

into the next, into the next,

rather like an ice cube tray.

- The weight of the water is forcing the bow

of the ship down and the ship begins to tilt.

Passengers begin to feel it and as the weight gets heavier

and heavier, that angle increases.

- Now the heaviest parts of the ship are the two engines

in the rear.

So you have a large heavy concentration here

due to the engines,

but you have a large heavy concentration here

due to the water.

- And so basically you have an issue of weight

and displacement and eventually

the ship can't fight it anymore.

[dramatic music]

- [Laurence] Some argue that the Titanic

would've been better off with no bulkheads at all.

- The ship builders believed

that they had thought of everything

when building the Titanic, but they were sadly mistaken.

- What they didn't anticipate

was that an iceberg collision

could scrape along the side of the ship and cause damage

in six compartments.

They were imagining it might be a head-on collision

or a puncture.

- This design feature ends up being the problem

because with all of this water that's seeping into the front

because it's got nowhere else to go

because it's being sealed off,

this causes the front of the ship to dip

below the water line and ultimately sink.

Had there not been any bulkhead walls there,

the dispersion of water might've been much more even

because it wasn't going from adjacent compartment

to adjacent compartment, it would've taken longer to sink,

which meant more people could have been saved.

That design was a catastrophe waiting to happen.

- The Titanic's tragic story captures the imagination

of the public and experts of all kinds,

who still seek answers about how and why the ship sunk

decades after its demise.

In 1985, more than 70 years after the tragedy,

explorer Bob Ballard makes the discovery of a lifetime,

the remains of the Titanic

two and a half miles down on the floor

of the Atlantic Ocean.

- So Ballard's find begins a whole new era

in the story of the Titanic,

and allows us for the first time

to try to understand what really happened.

- Other explorations head down to the ship

and they end up bringing up about 5,000 artifacts

for scientific exploration.

- Expeditions in the late nineties brought back

a lot of material including steel and rivets.

I was lucky enough to be able to examine those materials

along with my colleague Dr. Tim Foecke

at the National Institute of Standards and Technology.

- In their book "What Really Sank the Titanic,"

they posed their theory as to what they believe

actually led to the Titanic sinking as rapidly as it did.

[dramatic music]

- Titanic's hull is built like a patchwork quilt of steel

where you have big steel plates

and these are stitched together by metal rivets.

- A rivet is essentially a two-headed nail,

so plates would be placed together with pre-punched holes

and a rivet would be passed through that hole

and then hammered on each end to create a head

and effectively a watertight seal.

- [Laurence] The Titanic's hull is held together

by 3 million six-inch long rivets.

These are traditionally made of steel.

As Foecke and Hooper examine Titanic's rivets

under a microscope, they make a stunning discovery.

- Titanic was built using two types of rivets,

wrought iron and steel.

Steel was used in the middle section.

That makes sense because the center section

of the Titanic is going to feel the highest stresses

during its voyage.

In the bow and the stern, they used wrought iron rivets

and when we think about the collision

what's important

is understanding how and where it happened.

It happened in the starboard side,

low on the hull of the ship

but across the bow and six compartments all in an area

that was wrought iron rivets.

- Wrought iron traditionally is a much softer metal

than steel, not to mention in these rivets

they also find a high percentage of what's called slag.

- Slag is a byproduct of how we create wrought iron

and it helps to mix and remove impurities from the iron

when it's created.

In traditional wrought iron that's used

for ship building, bridges, fire escapes, the Eiffel Tower,

this material has about 2 to 3% slag.

On Titanic, the wrought iron had 9% on average

up to 12%, which is three to four times

what you would normally see.

It can create weakness exactly in the places

where you need it to be holding the ship together.

- [Laurence] So why would the builders of the Titanic

use rivets made of impure irons that might not be as strong?

- There was a lot of stress and there was a lot of pressure

to complete the Titanic on schedule.

In order to do that, they had to find ways to source iron

and steel as rapidly as they could.

In 1901, they stopped requiring testing of iron

for ship building.

Iron was easy to source, faster to source,

and they knew that they could rivet it up quickly.

- So the rivet itself is half the tale.

The second half of the tale is how many rivets are used.

The more rivets you put,

the more effective that joint strength is

to the strength of the steel plate

that it's trying to connect.

In the places up forward where damage was observed,

there are less rows of rivets,

so right off the bat you have a weaker joint to begin with.

Add to that, now you have these potentially weakened rivets

or poorly manufactured rivets

and you have a place where the seams may fail

with less force than might have been expected.

- The wrought iron material on Titanic under the microscope

has particles of slag that, in some cases,

are so small you can't see them with the naked eye.

So when we think about the disaster

and the role that materials played

in one of the most famous ship sinkings,

we're literally talking about microscopically small material

that could have taken down a ship that was 800 feet long.

- [Laurence] These findings lead the two scientists

to a new realization.

- During the collision with the iceberg

as it hit the starboard side,

it's hitting and straining sections of the ship

where there's wrought iron rivets.

The rivet's already under a lot of strain

because it's holding those plates together,

so it doesn't need much for the iceberg

to begin that glancing blow that then causes one head to pop

and then the rivets next to it

are holding more of those plates and then they begin to pop.

So you can imagine a series of rivets

whose heads are popping almost like the opening of a zipper

along the side of the ship.

When we did computer modeling

to look at how steel rivets perform versus wrought iron,

we saw the steel could withstand five times the stress

before it would pop.

- So the question that comes out of this understanding

is were these weakened rivets

potentially part of the failure, part of the sinking story?

It's possible they were.

- [Laurence] After countless expeditions to the wreck,

scientists think they know what contributed

to the Titanic disaster.

Then in 2012, an unexpected treasure

is found hidden in an English attic.

- A bunch of old photos are found,

many of which are of the ship Titanic

during the last days of its construction.

These photos were taken by a man named John Kempster

who was the chief electrical engineer at the shipyard

where Titanic was being built.

No one knew that these photos existed,

but after looking at them

it may reveal something about Titanic

that we never knew before.

- The photos are sold at auction,

but before that, Irish journalist, Senan Malony,

is able to study them in detail.

- There's some discoloration on the exterior hull

of the ship in and around the area

in which the damage occurs

that causes the sinking of the Titanic.

- At first, he just assumes

that it's maybe like a reflection off of the water,

but in other photos he starts to see

the same black streak appear

and he thinks this might possibly be the culprit.

- At the time of the Titanic's sailing,

oil had not yet become a fuel of choice.

Coal in the form of coal bunkers were how we stored

the chemical energy to drive the ship through the water.

- Titanic carries 6,600 tons of coal

in these 30-foot-high bunkers

that sit next to the hull of the ship

as well as the interior bulkhead.

Coal is shoveled into these gigantic boilers

of which there are 29 of them aboard the ship

and they're thrown in there by these stokers.

[sound of shoveling]

- In April, 1912,

when Titanic set sail on her maiden voyage,

there was a coal strike

and so coal had been transshipped

from a number of other vessels.

- Titanic stoker, John Dilley, survives the accident

and afterwards he tells a report of it.

Even before Titanic set sail,

a coal fire had started in one of the bunkers

and it continued to smolder and continued to be ablaze

even after the Titanic took off for sea.

- Every boiler front and furnace was very accessible

to the local supply of coal.

This place, these coal bunkers adjacent

to this watertight bulkhead

and so that becomes a concern when the fire begins.

- Malony theorizes that the black streak

on the side of the ship

is because of an uncontrollable fire in the coal bunkers.

- Maybe this burning fire could have damaged the steel

of either the hull

or the adjacent watertight bulkhead

that separated boiler room six from boiler room five.

And if that's the case,

perhaps a failure of either of those two structural elements

could have contributed, if not caused, the ultimate sinking

of the Titanic.

- [Laurence] Records show the Titanic's coal

had been loaded into the bunkers

three weeks before she set sail.

Malony believes it's possible that's when the fire started.

- One kernel of coal can heat up

and because it's trapped within these giant 30-foot bunkers,

it can smolder for quite some time

before being detected,

which could ultimately lead to it starting and spreading

a much larger fire.

From the bowels of the ship

right at the very bottom of the ship,

there's no place to dump coal overboard.

There's no place to just dump it into the water.

- [Laurence] The stokers on the ship

are left with only one choice.

- Bunker fires in ships can be very dangerous

because the coal burns very, very hot

so that if you play a hose on it,

it just evaporates the water.

So the best way to extinguish a bunker fire on a ship

is by raking out the coal and putting it on the boiler.

It took Titanic's firemen four days to rake out

all the burning coal before the fire was fully extinguished.

- [Laurence] With the coal bunker empty,

the crew can see the damage caused by the coal fire.

- A stoker tells investigators, after the sinking,

that one of the bulkhead walls was red hot at the time.

It is possible that that amount of heat

could have very well discolored the metal wall

within the ship, which leads to that black mark

that Malony saw in those photos.

- Other stokers talked about seeing that steel

of the bulkhead being red hot.

Steel when it achieves a certain temperature

can change phase.

It changes its form and can become brittle.

- [Laurence] Malony's theory

is that this fire- damaged bulkhead

is the key to the sinking of the Titanic.

- In the bulkhead wall that's been damaged

by the coal bunker fire,

we now have the final two compartments that flood

as a result of the collision.

So you can imagine that the stress caused by oncoming water

and the flooding of water as it gushes

through the starboard side,

maybe the bulkhead wall was already weakened or embrittled

because of that coal bunker fire

and may have failed sooner than expected.

- [Laurence] But why would the Titanic have knowingly set sail

with an ongoing coal fire?

- Malony suggests that the ship set sail

because the White Star Line was already receiving bad press

due to the fact that the maiden voyage

had been delayed by about three weeks.

- [Laurence] Not everyone believes the coal fire

was burning hot enough to cause any structural damage.

- If Malony's coal fire theory is true,

the damage to the interior watertight bulkhead

should have caused the water pressing against it

to damage the structural integrity

and the bulkhead would've collapsed right away.

But we know due to testimony of the crew

that the bulkhead did not give way for over two hours.

- The coal bunker fire on the Titanic

was located directly under the first class swimming pool.

If the fire had reached 1800 degrees Fahrenheit,

the passengers on that deck

would have definitely felt that temperature.

In addition, the stokers,

the people working around the engines

that were coming in and out of that room

would've needed protective gear to get that close.

It's just hard to imagine that it would have gotten that hot

and we wouldn't have seen or heard anything

from the passengers on the ship.

- So maybe if coal was burning that hot,

it could have damaged the bulkhead

and it could have compromised the ship,

thus leading to its sinking.

But at the end of the day,

regardless of damaged bulkhead or not,

when the Titanic hit that iceberg, its fate was sealed.

[waves crashing]

- [Laurence] The question of what really caused the Titanic

to sink after the iceberg collision

has been asked since the day the infamous ship went down.

- By the time the Carpathia pulls into New York,

the press are waiting, the public's waiting,

the politicians are waiting.

How could something so grand, something so large,

the pinnacle of technology of our day disappear

in two and a half hours

and with 700 people surviving out of 2,200?

This is hard to imagine.

People want answers.

- [Laurence] From excess speed, to structural flaws,

to a secret fire,

if any one of those was managed,

could the tragedy have been prevented?

- When disasters like the Titanic sinking occur,

we often want to point blame at one person,

one specific factor.

- Could it have just been one thing

or was it a perfect storm of multiple different factors

that contributed to

this sinking event of epic proportions?

[dramatic music]

- There were many mistakes

that could have easily been avoided,

everything ranging from high speeds, to structural issues,

to a secret fire, just layer upon layer of issues

that compounded on top of each other.

- Like almost any accident.

There is a cascade of events or situations

that occurred to bring us to the point

where the failure occurs.

- It's not one thing that causes it, but a series of things.

- One analogy might be if you throw a rock down a mountain,

you might be able to stop the rock,

but once it becomes an avalanche, it's game over.

- It took decisions, it took flawed material,

it took bad environmental conditions, mother nature,

to bring all these things together in one place

and cause an accident.

- This was a perfect combination of many events

all happening at the same time at the very same place.

- [Laurence] More than 110 years later,

all the theories and evolving evidence

haven't dampened the passionate curiosity

surrounding the Titanic's demise.

- People are still fascinated by it.

When you think of all the people on Titanic, rich and poor,

and crew and passengers,

it's a bit like a microcosm of humanity.

And then the iceberg lurking in the darkness

almost represents the awesome power of nature

and the universe.

So really, the story of the Titanic

speaks to the human condition.

- There's probably more down there than we realize.

As a disaster it leaves us wanting to know more.

- Carpathia rushed to the scene, saved 712,

and it's those people we have to remember today.

The 1496 who did not survive all still have stories to tell.

- Titanic is always gonna be one of those instances

that is constantly studied, constantly picked over.

As technology continues to improve

and advance,

who knows what new discoveries we might make about Titanic

as it sits at the bottom of the Atlantic Ocean?

And ultimately we might end up finding the real reason

why Titanic sank to the bottom of the ocean so quickly.

- If the wreckage could be raised,

we might answer more lingering questions

about the Titanic's final hours.

Until then, so much remains a mystery.

And with Titanic's hull predicted to collapse

by the year 2030, battered by deep sea currents

and consumed by bacteria,

the last secrets of this notorious ship

may soon be buried forever.

I'm Laurence Fishburne.

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

[dramatic music]