Red Sea Oceans

They cover two thirds of our planet.

They hold clues to the mysteries of our past.

And they're vital for our future survival

but the secrets of our oceans have remained largely undiscovered

until now.

-I am with a six gill shark.

-Yes, yes!

Explorer Paul Rose is leading a team of ocean experts

on a series of underwater science expeditions.

For a year the team has voyaged across the world to build up

a global picture of our seas.

We are doing some pretty uncharted research here.

-That is psychedelically powerful!

-We're here to try and understand

the earth's oceans and put them in a human scale.

Our oceans are changing faster than ever.

I've never seen ice like this before.

There's never been a better time

to explore the last true wilderness on earth.

Eritrea, East Africa.

The team is heading to the southern Red Sea.

I feel like I'm a kid again. You know, you say can you smell the sea?

The Red Sea is technically an ocean because it was formed when

the continents of Africa and Asia tore apart millions of years ago.

Unlike the tourist diving Mecca to the north,

the southern part remains remote and untouched.

By and large this is unexplored.

It's uncharted territory, particularly under the water.

The southern Red Sea is one of the most important marine sites

in the world.

Home to a spectacular array of species,

many found nowhere else on earth.

The team has come here to discover how this small sea

could hold clues to the future of all our oceans.

Environmentalist Philippe Cousteau Jr

wants to investigate whether these waters,

some of the warmest on earth, could help our oceans cope

with the threat of global warming.

We need to figure something out

that is going to help all the other coral in the world.

This sea is one of the most significant in human history.

Maritime archaeologist Dr Lucy Blue is searching for evidence

that it was here that early modern humans

first left Africa and populated the planet.

Well, that's fantastic.

Marine biologist and oceanographer Tooni Mahto wants to witness

something fundamental about our oceans...

How they're born.

If you don't dive in the Red Sea, all you see is...

that. That's all you see.

You see blueness.

To understand anything about what happens in our planet's oceans,

you have to get in.

But 30 years of war

have kept this unique stretch of sea virtually inaccessible.

Now for the first time, an expedition like this

has been allowed in.

Hello, sir. Very good to meet you. My name is Paul.

Well, this is just one little bit of paper but it means a lot to us.

I mean there it is, that's our permit.

It's a single permit and it took us

ten months to get this thing,

but it doesn't give us any protection against

any of the other things that are probably going to go wrong.

This is definitely an ambitious expedition.

No doubt about it.

For the first mission,

Tooni and Philippe will investigate how our oceans formed.

They're heading south to Djibouti,

a country at the gateway of the Red Sea.

Here the world map is being re-drawn

as a completely new ocean is created.

I'm fascinated by how the earth looks today

and why it looks today the way it does,

and I'm also fascinated by this idea that actually the land is moving,

is constantly moving, constantly changing.

But to actually go and experience that I think is, is really key.

Right here beneath this bay, huge tectonic forces have formed

a crack beneath the earth's crust

pulling apart the plates of Africa and Arabia.

That process forms all our oceans

but this is one of the only places

in the world where you can dive

and see it in action.

We've come here to witness something that's really, really special.

We're hoping to basically witness the birth of an ocean, because...

it is literally where a new ocean will form over millions of years.

So it's splitting the land apart?

It's splitting the land apart and this area will one day flood

with water from the Indian Ocean and the Red Sea,

so we will be over two completely separate land masses

-that are moving away from each other.

-Are we going to be able to...

-How close are they together? Do we know?

-I don't know. Time will tell.

I want to see if I can touch two continents at once.

On the seabed, they're looking for the opening, or rift.

Go that way.

I think it's over here.

An incredibly dark opening.

At least that's my impression of what a rift should look like.

Ladies first!

I'm going down.

Descending into the rift that has opened up.

They dive down, disappearing between Africa and Arabia.

It just drops down into complete nothingness.

Not quite what I expected at all.

It's a tight squeeze through some of these passages.

Gotta be really careful.

This rift has been formed by the action of the earth literally

ripping itself apart.

Just think of the amount of force that it would have taken.

The narrowness of the rift shows that it's right at the beginning

of a process that will continue for millions of years.

Normally it's happening thousands of metres down

so it's extremely rare to see this so close to the surface.

As the rift widens, magma from beneath the earth's crust

rises and solidifies to form a new ocean floor,

gradually pushing the plates further apart.

Let's put a hand on one continent each.

I've got, I've got the Somalia plate on the end of my finger,

and this is the African plate,

and Philippe to the right has got the Arabian plate.

Between us we're actually spanning two continents.

Over time, these two bits of rock will move away from each other.

They're moving at a rate of about two centimetres a year

which is about the same rate as a nail growth.

In millions of years, this gap could be as wide as the Atlantic.

So this could be New York and that could be London.

As these plates pull apart, water floods in, creating the new ocean.

Not many people get to be at the site of a new ocean.

It's like seeing how the Red Sea once was.

It's a pretty remarkable feeling, the beginning of an ocean.

It's stunning. The reality of it is that

those two bits will never touch again,

and will keep on moving and moving for pretty much eternity.

Millions of years from now,

hundreds of square miles could be covered by water,

the new ocean, and it's already been named...

the Afar.

Tooni and Philippe are heading back

to rejoin the expedition in Eritrea.

The plan is to sail north

to discover why the Red Sea is so important in our history.

And how its marine life could help all our oceans survive.

But as one of the first teams allowed in here,

nothing is straightforward.

Hello!

'Fuel is rationed in this country,'

and the Nemo is full and we need another 5,000 litres

to complete the mileage.

I'm calling again about our fuel.

The Navy have given us a huge amount of support

and they're going to put one of their people on board.

Hello, good to meet you.

You look after us and we'll look after you, how's that?

It's not long before he needs to help out.

Just need a bit of a hand to see if...

Filming's barely begun before soldiers put a stop to it.

We don't want to film their... the ship or anything...

From the BBC Oceans expedition.

Oh, it is confirmed.

We can have the 5,000 litres. Well, that's fantastic.

With enough fuel promised for the journey, it's time to leave port

and head off for the next target.

It's a two-hour trip east,

and many thousands of years back in time.

She's flying!

Recent findings suggest this

was one of the first seas early modern humans ever saw

before making their way out of Africa and across the globe.

For maritime archaeologist Dr Lucy Blue,

it's a rare chance to investigate such ancient human activity.

I think it's really important, because people

don't really understand the first time people encountered the sea,

or what they did when they got there,

and this is some of the earliest evidence that there is

for early modern humans settling in a coastal environment.

Lucy is hoping to find clues preserved here

about the first encounters our ancient ancestors had

with the Red Sea.

I'm really finding it fascinating.

It's like a big jigsaw and you've got all these little pieces that,

well not many of them, actually, to put into the puzzle.

And... I'm really...

and I'm also interested in the nature of the finds

because they are very different to what you find on most sites.

You've haven't got ceramics or building remains.

It's a different type of site.

The hostilities may be over, but this is still

very much a military zone and access is heavily restricted.

Soldiers watch their every move.

Wow, there's a lot of military bases there, aren't there?

All of that is the military encampment.

Pretty good guns up on top there, Lucy.

There's a bit of waving, let's wave back.

It's always a good thing.

Normally, they'd have to dive down to the sea bed to look for clues

but here the sea floor has come to them.

Over thousands of years, earthquakes have raised up

the ancient coral reef by ten metres.

With it, a slice of history that's 125,000 years old

has been pushed into daylight.

This is all old coral. I mean,

Look at some of this.

If there's any doubt about whether that's coral or not, you know...

Buried in this ancient coral,

they're hoping to find evidence of early modern human activity.

What we need is some sort of... just chuck a load of water onto it.

Hey, Lucy! Look at that. That bit.

Oh, yeah, that's more like it.

-That's got to be.

-You've really got to, that's fantastic.

-Look at that.

-Oh, that's beautiful.

-Give it a spray.

That's what we're looking for.

-It's an ancient hand blade.

-That can take skin off, no problem.

Well, be careful because you can and that's part of the reason

that we can tell it's not been moved you know by water action or the sea.

It's been deposited here in its original context because

it's still pretty sharp.

See how, if you hold it that way it doesn't feel quite right.

Hold it this way, you see that's curving down and this is curving up

-so depending what you were going to do with it...

-Yeah, that's true.

Because look at that, that shape. That is a proper beautiful tool.

That's beautiful.

This type of tool, made from volcanic glass called obsidian,

dates from the middle Palaeolithic period.

There's no other obsidian here, so it must have come here

through some sort of human action.

So early modern humans were definitely here

but is there evidence of their relationship with the sea?

-I think that's maybe what we've been looking for!

-Yep.

They've found what appears to be an ancient oyster bar.

Imagine if you're shucking all these oysters. Look how well that fits in.

You know, just... it just fits perfect, doesn't it?

So you can just imagine this whole area where people have come,

they've collected the shells, they've processed them,

they've eaten them and they've just thrown them on the floor

and I think that's just, it's just fantastic.

You can see it in such a distinct horizon.

Early modern humans were probably

driven from the central plains of Africa by drought.

They would have stumbled across the Red Sea

in their search for food and water.

It's very significant in a lot of ways

because it shows one of the first, if not the first, bits of evidence

that we have for human interaction with the sea here on the Red Sea.

It's a really...

exciting feeling to hold some tools and the last man to use this...

was 125,000 years ago.

These tools show how our ancestors learned to exploit the Red Sea.

For the first time

they had a food source that didn't rely on the climate.

And when sea levels dropped, these thriving coastal people

had the opportunity to cross this narrow sea

out of Africa and eventually populate the entire world.

The Red Sea has always been a critical point of communication

and trade and transportation, but I hadn't, until today, appreciated how

incredibly early that communication and contact with the sea started.

It just gives it such depth.

That's the past.

But it's what the Red Sea could tell us about the future of our oceans

that's brought environmentalist Philippe Cousteau here,

particularly his concern for coral reefs, the rain forests of the sea.

Probably one of the most critical issues that ocean conservation

is facing over the next decade or so is the loss of coral reefs.

Coral is vital to the health of the ocean,

harbouring a huge diversity of life.

But rising sea temperatures across the world

are causing much of it to suffer from bleaching...

to turn white and die.

Of all the coral reefs in the world, we've lost about 25% - are gone.

Another 25% are heavily threatened

and we fear will be gone within the next 50 years or so.

The Red Sea is the perfect place to study the impact of warming seas.

Water temperatures here are among the hottest on earth,

reaching 34 degrees Centigrade.

We've got the monitor right here and we're going to submerge it maybe...

ten metres underwater, about 30 feet.

It's winter now and Philippe wants to find out

what the corals are dealing with.

The temperature reads 27.8 degrees Celsius, almost 28 degrees Celsius.

That is too warm.

That's just not an optimal temperature range.

You know it's winter time.

Winter, I don't like to see this so I'm concerned about what's going on.

Joining Philippe is Eritrean marine scientist, Yonathan Bockre,

one of the few people to have spent any time on these reefs.

I know basically, you know, the coral types here

so this is a great opportunity for me.

Yonathan thinks there's something surprising about this coral,

and the team is now keen to investigate.

I've been dreaming of getting into the Red Sea all my life,

so the chance to do so now is pretty spectacular.

And then to be able to do it here in Eritrea where few people

have ever dived before, let alone filmed before, is...

is probably one of the most exciting dives of my life.

With such high winter temperatures,

there could be a lot of bleached coral.

I can feel the water. I almost don't need a wet suit, it's so warm.

It is looking pretty beautiful... What a relief!

Astonishingly, the coral is far from dead.

It's flourishing.

I'm so amazed at how healthy this coral looks.

In all my experience,

this coral should not be thriving the way it is.

You see all the fish swimming in the water column

and that's the symbol of a healthy, healthy reef.

The first thing we need to do is to see what's down here and where it is.

It's just so full of stuff here.

It's really hard to do this because everything is overlapping.

It's so dense and so rich it's actually quite difficult to map.

Coral reefs are the life support system of our oceans.

Without them a quarter of all known fish species would be under threat.

There are small patches of bleached coral here

but according to Eritrean scientist, Yonathan Bockre,

even these damaged corals recover faster than you'd expect.

What is so unique about these corals is that

even in the extremely high water temperature, they manage to survive.

Anywhere else in the world,

these conditions would spell disaster for the corals.

Something very unusual is happening here.

-It's important to find out what because it might just help

other coral reefs avoid the ravages of global warming.

The water is really, really warm.

There's no way, in my experience,

that that coral should be doing that well, but it is.

We need to figure something out that is going to help

all the other coral in the world,

and if it's possible to do that here,

this place is like a gold, solid gold mine.

I mean this is a gold coral because, it's platinum, diamond coral,

it's so valuable because if this holds that secret...

then there's hope.

To understand what's going on,

they need to take small samples of the coral.

Here you go. That's plenty, that's all we need from this one.

Coral is a complex organism that's both plant and animal.

Inside the animal part, the polyp, is a type of plant known as algae.

It's this algae that gives the coral its colour

and provides vital energy through photosynthesis.

When water temperatures get too high, typically what happens -

the coral loses the algae. The algae is stressed to such a degree

that it leaves the coral skeleton.

This is coral bleaching.

So the secret of these corals' ability to survive

must have something to do with the type of algae that lives within it.

One of the theories as to why this coral is able to survive

in such high temperature water

is that it harbours a specific heat-tolerant algae.

The special heat-resistant algae

could be what's keeping this coral so vibrantly alive.

It may be adapting to rising sea temperatures.

If so, this Red Sea coral

could hold the key to helping the rest of the world's coral too.

The hope is that if we can isolate that algae, we could potentially

grow it in the laboratory and literally inoculate

other coral reefs around the world, so that when they bleach,

this algae can move in and the corals can survive.

It may sound like science fiction but leading coral scientists agree

that heat-tolerant algae might one day provide a way

to protect corals worldwide.

I'm going to put that pyrites in there...

I think it's mind-boggling to think that it's samples like these

that could hold the key to global coral conservation.

As climate change is encroaching, sea temperatures are rising,

there's a lot of concern and...

whatever is making these corals tick, hopefully it is this algae.

Whatever it is, it's very exciting.

The investigation doesn't finish here.

There are more mysteries within the coral but they can only be revealed

under cover of darkness.

While they wait, Lucy and Philippe

have been invited to the nearby island.

That would make an excellent frame in a boat.

A limited resource is being destroyed by Cousteau.

They're going to have a lesson in traditional Egyptian bread-making.

It's something very unique to each country.

I've never even heard of cooking bread in sand. I love it!

It smells so good.

-It's not every day you get to make bread on a beach, is it?

-No!

Now that it's dark, they can dive.

They're looking for evidence of another way

these corals might cope with the extreme conditions here...

a mysterious phenomenon which causes some corals to fluoresce, or glow.

It'll be a complicated dive.

Normally when we're on a night dive, we've got a nice bright, white light.

But so that if there's any fluorescence at all,

to help us see it, we've got these flashy blue lights

and it's the blue lights that will help us see the fluorescence

but of course they have to turn the white ones off.

So that's where it kind of doubles up the risk factor. We can't quite see.

Nobody has ever had a chance

to look for fluorescing coral in these waters before.

As a marine biologist, Tooni will be the first.

Scientists have a difficult time of getting here

as it's so logistically difficult

and it's so un-dived that if we do get to see fluorescent pigments,

I think it will be a first for me to see them full stop,

and a first in Eritrean waters as well,

so it's a real kind of double winner.

Three, two, one...

go!

There's no way of knowing what to expect.

They may see none at all.

OK, so these are sort of our sci-fi glasses, I guess, aren't they?

The yellow goggles filter out specific wavelengths of light

to help them see if any of the corals here do fluoresce.

The blue light's on.

With a regular dive torch, this is what you see.

But with blue light and yellow goggles.

Oh, look at that! It does work.

Wow!

It just jumps out at you instantly, doesn't it?

As soon as you put the torch on,

it just picks out different spots of coral.

I've never seen anything like it.

It reminds me of a 1980s disco.

This extraordinary phenomenon is produced by fluorescent pigments

found in the tissues of a variety of coral species.

That's, like, multi-coloured.

There's a huge amount...

of fluorescence on the reef.

I think we're freaking some of the fish out

with our blue lights, by the way.

Why corals fluoresce is a scientific mystery

but it might be one way they've evolved to deal

with the intensity of the sunlight that's bombarding them.

One school of thought is that it's likely

the fluorescent pigments in this particular coral we're looking at

has a protective function from the very, very strong sunlight.

The fluorescent pigments might be screening out

some wavelengths of light, acting almost like a sunscreen.

If these fluorescent pigments are actually protecting the coral algae

from sun damage, then it means that

there's a very good chance that these corals will remain healthy.

The large amount of fluorescence could be another reason

why these corals are coping in these hot waters.

The marvels of the Red Sea...

never cease to amaze.

-Tooni, what do you reckon?

-That was so cool.

But to me it was more like why it's working, why it's important,

all the wonderful things that are happening in the sea that we don't understand,

we don't have a clue about, that's the power of it for me.

There's another secret bit to the recipe of survival.

It doesn't give up its secrets easily, that reef.

Time to break the Egyptian bread.

Make sure there's no sand in it.

You have to bury it so you build a fire,

-and then it goes down to the embers.

-We built the fire.

And for the bread to break Tooni.

I've just cracked a filling.

You've just cracked a filling?

-Just cracked a tooth.

-It's a little hard.

There's no need to be rude, now!

I've just cracked a tooth.

There's no shortage of skills an expedition leader needs.

-I might, I might put a temporary filling on there.

-Have you got a...

I do, yeah.

I'm not a trained dentist

but I have had some training by the Royal Air Force,

some years ago, so, so I've had some practice.

When you say some years ago...

That was in '91 I had the training, come to think of it.

-Let me just have a look...

-OK, where you do want me?

Just open up and lean back a bit if you can.

This is an old tube, it's all we've got.

Does that hurt?

Don't move, don't move.

It doesn't look too bad, you know?

Sorry, Tooni. Didn't want to push the...

-Thanks, man.

-All right, well done.

-Blimey, sweating bullets!

-Me too.

Today, it's time to leave Eritrea and head north to Sudan

to continue the exploration of this untouched part of the Red Sea,

but there are fuel problems again.

We're trying to hurry things up here.

It's late, we're... it's an hour late.

Haven't got much of a back-up plan.

If the fuel doesn't arrive, we'll be stuck in these waters.

As expeditions like this are so rare,

the send-off has become a local event.

INAUDIBLE

We've been over-run by, by officials today.

It's all important. We've now got the British Ambassador arriving.

I'm going to go present my credentials.

-Hello, I'm Paul Rose. Nice to meet you.

-Pleased to meet you.

-How you doing, all right?

-Very well.

-Would you like some tea or something?

-I'd love a cup of tea.

-Great, OK.

At last the promised fuel arrives.

We've got the fuel, thank heavens.

Yeah, I was very, very pleased there to see the truck,

so pleased to see the truck that I temporarily forgot

to check that it's the right fuel for us.

It's, this fuel is marine diesel, yeah?

With the right fuel on board, it's a traditional goodbye

to the Eritrean chaperones.

How good is that? We're on our way.

The team is heading to the waters off the coast of Sudan,

to a very special site.

To an underwater village,

built by Philippe's grandfather, Jacques Cousteau.

The journey is helped by the seasonal winds

as they follow an ancient sea passage.

The Red Sea has always been an important trade route.

Used by the Egyptians and Romans, it became part of the spice route,

but that's not all that was traded.

There's evidence of slaves, for one,

but tortoiseshell and elephants,

particularly in the Ptolemaic period.

Just imagine them building these Hellenistic boats,

-transporting elephants.

-Live elephants?

Yeah, they were training them to use in their armies.

2,000 years ago there would be a boat passing full of elephants!

It's halfway through the expedition

and everyone is exhilarated by what they've discovered,

but praying on environmentalist Philippe's mind

is the contrast between the southern Red Sea

and other oceans he's explored.

Seeing that balance between really healthy coral,

very little bleaching,

no real damage, human damage anyway, but in a way it reminds you that...

all the other reefs we dive on are in really bad shape because

this is what they should look like.

Sudanese waters are also unspoilt and will offer the chance

to look for rare creatures under threat in other oceans...

..but getting access has been complicated.

There's a good buzz at the moment but you've only gotta have

one official that hasn't been kept in the picture by other authorities

or some little muddle like that, and we're going to be stuck here

and once you get stuck in these places, then you're really stuck.

Next day things take a turn for the worse.

The seasonal winds have changed direction

sooner than expected.

Yeah, it's too bad.

I mean we've left the Suakin island group

and we're heading towards Port Sudan now

but we're being slowed up by this flipping wind.

The boat's fighting a fierce northerly wind.

If they don't get to Port Sudan in time to meet the authorities,

they could be held in port.

It's another 24 hours of ploughing through choppy seas

before Port Sudan finally comes into sight.

We're close enough now. I need to pass the message.

We've all got to get changed.

We need long pants out of respect of custom here.

The Sudanese authorities rarely deal with an expedition of this size.

The port officials and security want to board immediately.

The Department of Security has also insisted

that one of their men remains on board.

The chap with the dark suit jacket and the cool-looking shades,

he's got to be our man.

As-Salamu Alaykum.

As-Salamu Alaykum.

While the authorities search the equipment,

maritime archaeologist Dr Lucy Blue

is drawn to one of her favourite subjects - shipwrecks.

-Wreck city up here.

-A graveyard.

-There's one over there, one here.

Because of their shallow reefs,

Sudanese waters are littered with wrecks.

But Lucy's been researching an Italian cargo ship, the Umbria,

which was sunk on purpose near the start of the Second World War.

Her captain wanted to stop the British Navy

getting its hands on her top-secret cargo.

It was quite a brave thing to do, really, when you've got,

you know, a crew of British officers on board,

actually rifling through your cargo and trying to detain you.

I'm seeing parallels with the fact that

we've got customs officials downstairs,

-rifling through our gear.

-That's a good point!

Oh, these are health. OK, yellow fever, any deaths,

any mice, rats, any infectious disease.

OK, well, I'll go through this. OK, sir, see you later. Thank you.

In World War II, the Red Sea was an important route linking Europe

with India and other British colonies.

The day Italy declared war on Britain,

the captain of the Umbria decided to sink his own ship.

The vessel itself is listing at about 60 degrees,

so you get this really distorted impression.

I don't think I quite appreciated the scale of a 150 metre long ship.

Lucy wants to investigate the cargo it carried.

She soon comes across artefacts that hint at life on board.

Look at this!

There's thousands of wine bottles

scattered all over what remains of this hold.

La dolce vita!

This is a huge, vast space.

This must have been the restaurant or the dining area or something.

And you can still see the stumps from the bottom of the tables.

It's like entering into the lives

of the people that were living on board.

It just looks completely eerie.

I've just got images of Titanic going through my mind.

When the Umbria left Italy, the country wasn't yet at war

so this was officially a neutral cargo ship.

Oh, yes!

Three Fiat Lungas.

There's glass, there's a driver's seat and everything.

The boat's sitting at an angle

and they've just fallen down on top of each other.

But it's not the cars they're here for.

It's the 5,510 tons of cargo in the next hold.

This is amazing.

There are just thousands and thousands of bombs here.

Just literally surrounded by stack upon stack upon bombs.

In fact there were 360,000 bombs on board this cargo.

These aircraft bombs were en route to Eritrea,

then part of Mussolini's Italian Empire,

for use against the Allies in East Africa.

It's easy to understand why the captain didn't want

the British to get their hands on this deadly cargo.

To see them laid out like this is just bizarre.

I know.

The power, the power of destruction that still remains in this ship

is a little bit overwhelming.

Over 600 crates of detonators are stacked separately,

so these bombs shouldn't explode.

But if they did, there's enough firepower here

to destroy half of Port Sudan...

over 20 miles away.

The bombs are just overwhelming, they really are incredible.

They're stacked like eight deep and goodness knows, into the hull,

how deep they go and it's just, you just think what possesses man

to want to, you know, just destroy, destroy on that scale.

The team is due to visit one of the most audacious and extraordinary

ocean-bed experiments ever attempted.

It was the brainchild of Philippe's illustrious grandfather,

Jacques Cousteau, who spent years exploring these reefs.

The Red Sea has always been an important place in my family's work

and I've grown up with stories about the adventures that they had.

I think it's almost like a pilgrimage, coming here for me.

Kind of gives you an idea of the overall space

the village, the community, as it existed.

Captain Jacques Cousteau dreamed up Conshelf II,

an underwater village built in 1963.

It was designed to see if humans could live beneath the waves.

Conshelf II was right off Sha'ab Rumi, which is right up here.

Yeah, it's quite a ways, actually, away from Port Sudan

but that was part of the idea.

It was quite remote.

It was a time of boundless scientific optimism.

Astronauts were heading up into space

and now oceanauts were heading down to the sea floor.

My father died in 1979, just six months before I was born.

My grandfather wrote a letter to him and he actually talks about Conshelf.

"Mon cher Philippe,

"I will always remember that day of July 1963 when you joined the Conshelf II expedition

"along the Sha'ab Rumi reef in the Red Sea.

"The sun was setting but I would not give you time to relax.

"I was too impatient to show you our village under the sea.

"Hastily, we both donned our aqualungs and slowly, sensually,

"we submerged into the welcoming water, as warm as our blood.

"We started for an unforgettable stroll with slow strokes

"of our long, stretched legs

"and breathing deep lungfuls of air."

This is it.

This is it.

God, I can't believe I'm here. I just can't believe it.

Thinking back to what it must have been like 45 years ago...

..and kind of envisioning these oceanauts with silver suits,

this was sci-fi!

I mean, this was before we landed on the moon.

This was the first steps of humans living in an alien environment.

But it has a real sense of being placed here deliberately,

and that is what's such contrast to what I usually find

in terms of the remains of human culture or activities underwater

where they've happened to end up there by default.

The five divers, oceanauts, lived on the sea-floor for a month.

I want to see what's inside it, too.

Yeah.

Today, this is all that's left of the underwater village,

the garage for their submarine.

Wow. How do you actually get in, Philippe?

Well, there's an entrance over here, I think.

The submarine would have come up underneath and slowly risen up

into the area in here, this submarine garage.

God, I can't believe I'm here.

No-one really understood the physiological

or psychological effects of living at pressure.

Here they were at twice atmospheric pressure.

Every morning a doctor carried out medical tests.

We know that cuts and nicks healed faster

because of the increased pressure

of the oxygen at depth that caused their body to recover.

They even had someone come down to give them a haircut every once in a while,

even though their beards and hair grew slower at depth.

It was so advanced for its time, wasn't it? It really, really was.

Fresh food and water were brought down every day.

But being French, they had wine and champagne,

which was flat because under pressure the bubbles didn't expand.

They did some of the first remote video capture of life underwater,

videoing things that no-one had ever seen before.

They observed new patterns of behaviour

and discovered several new species.

It was really cutting-edge science

and provided an incredible amount of knowledge for us

to take another step towards understanding

the relationship we have with the oceans.

By the end of the month,

this bold experiment had proved that man could live underwater,

although the Space Race was to turn everyone's thoughts

to a different frontier.

"I kept your hand in mine to guide you from Starfish House,

"where oceanauts were having dinner,

"to the onion-shaped diving saucer garage.

"Twilight was turning to sheer darkness

"and our structures became eerie shadows.

"The fish were just moving pieces of the sea.

"I was still holding your hand when we returned to the ladder.

"I felt strangely proud, not of what we had achieved,

"but because our dreams were always shared so intimately.

"I saw your shining face, proud to have something to give back to me,

"and I smiled because I knew that pursuing rainbows in your plane,

"you would always seek...

"You would...

"Because I knew that pursuing rainbows in your plane,

"you would always seek after the vanishing shapes of a better world."

After two weeks at sea, the expedition is almost over,

but there's one final mission.

In many parts of the world, fishing has dramatically reduced

the number of sharks, like these scalloped hammerheads.

That's amazing. Look how many there are!

I've never seen a school like that.

Today, it's incredibly rare to see large groups.

These were filmed over a decade ago.

We don't know very much at all about hammerheads

and it's really kind of the luck of the draw these days.

You know, even in places where you can still find them, it's hard.

It's so difficult for scientists to get to this part of the world

that there are no reliable figures on hammerhead numbers.

So, it's a great chance for Paul to see what he can add.

Been building up to this for a long time,

not even just on this part of the expedition

but I've looked for them before in my life and not found them.

There is a bit of pressure because it's an important expedition target

so, really, really, really want to find them.

See you, buddy!

There's little fishing in these waters,

so could this be an important haven

for fish that are jeopardised elsewhere, like hammerheads?

Finding a large group might indicate the population here is thriving.

Paul's heading to the edge of the reef.

It's just unbelievably pristine, look at it.

Here currents rise from the deep,

carrying nutrients which encourage plenty of fish.

Food for sharks.

That's good, we've got some grey reef sharks swimming round me now.

Fabulous things, aren't they?

It's definitely shark territory.

Grey reef sharks are agile, curious and often swim in packs.

Paul needs to be careful not to get too close

or make any sudden movements.

While Paul is swimming against the strong currents at 40 metres...

-Richard!

-..there's a problem developing on the surface.

-Richard, what's going on?

-I have to report we have an emergency situation out here.

We cannot pick up divers at the moment.

Engine's down on the Zodiac,

which means they can't go chasing the divers

in case there's an emergency because the current's so strong.

The engine on the rescue boat isn't working.

The team is worried because Paul is deep underwater,

swimming against strong currents,

and if anything goes wrong, there's nothing they can do.

But Paul is completely unaware of what's going on.

A single barracuda comes to investigate.

Above, a ball of them circle in the shallows.

No-one is sure why they do this

but they could be herding their prey towards the surface.

We're at 40 metres.

It's just wonderful to be in the blue orb of the welcoming Red Sea.

No hammerheads though. You've just got to happen to be very lucky

to be in the same place at the same time.

All right, Richard, we've launched our Zodiac.

The best we can do is get that boat out to you and swap motors

so that you've got a working motor on your Zodiac.

They're on our way, we've done everything we can as fast

as we could, Richard, over.

Paul has been swimming against the current for two hours

when he spots something very rare.

That's pretty special.

Can you believe it?

That's a sailfish.

Look at him.

Over a metre long.

Very rare, that.

These things are solitary fish and very, very unusual to see here.

He's got that dorsal spine up.

That's a sign of aggression.

Sail fish are the fastest fish in the oceans

and can reach 68 miles per hour.

But Paul has still not seen any sign of hammerheads

and with the boat trouble, the decision is made to halt the dive.

Had a great dive but no hammerheads.

We've got some boating things to figure out.

We don't do boating very well at the moment.

Really disappointing. At least I did get the hint of sharks.

It felt like shark water to me,

and so we're going to do a dawn dive tomorrow.

This is my mission on this expedition,

is to learn some more about the hammerheads.

But was seeing none today a sign that hammerhead numbers

in the Red Sea are declining?

5am - the last day of the expedition.

Paul's final chance to look for hammerheads.

He's heading back to 40 metres.

Just bursting with life.

Truly amazing, completely untouched.

Which is why these waters are in pristine condition.

Paul passes butterfly fish, feeding on the coral.

Almost one in five fish species found here

lives nowhere else on earth.

Suddenly, a rare silky shark comes close.

Recognisable because of its shiny skin,

it can grow to over three metres long.

Paul has been drifting along the edge of the reef for nearly an hour.

Then, something moves in the distance.

There you go.

A school of hammerheads, there's about 30 of them.

Look at that!

We've just seen one of the rarest sights on earth,

a school of hammerheads flying through here.

It's a distant sighting but still exceptional

to see them in such a big group,

and a very good sign for their population here.

What a gift.

Thank you, the Red Sea!

He saw them, he's giving the double thumbs-up.

He's giving the double fins!

Perseverance! You prevailed!

We've got to stop doing this last minute stuff,

-it's going to kill us!

-Fantastic.

-It really was great.

-Good for you, man.

-There was about 30-odd of them.

-30!

-30!

In many other oceans, a sighting like this

would be a thing of the past because of over-fishing.

It's another reminder that this part of the Red Sea is unique.

I've done over 6,000 dives but it was truly a marvel.

I have been looking for hammerheads for most of my diving life.

There's just something about them and I've never seen any.

A school of hammerheads flying through here.

Just by witnessing it, recording our experiences,

we have added to the science database here in the southern part

of the Red Sea because so little has been done.

It's a fantastic end to an expedition which has shown

just how important this small sea is.

The southern Red Sea gives you some indication of what the seas

used to be like and if we're lucky, what they could be like again

in the future if they're managed properly

and we give them a little bit more respect.

We are leaving this place richer in ourselves, richer in our knowledge

but there's so much that it holds that we don't understand,

and that's so exciting.

I came up from every dive I've done in Eritrea just feeling

really, really positive, and I don't think I've had that sensation

anywhere else in the world.

What we've learnt in the Red Sea is that oceans can survive.

It sounds odd but oceans are fragile and yet they can survive.

Next time, the team explores the vast Atlantic.

They'll brave the toxic world of our ancient oceans.

We are three and a half billion years back in time.

They'll investigate the invasion of a deadly species.

And try to protect a fearsome predator.

Sharks everywhere!

Subtitles by Red Bee Media Ltd

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