Original subtitles

The Cape of Good Hope, on Africa's southerly tip.

Here, two great seas meet.

One, the warm Indian Ocean, the other, the chilly Atlantic.

And as they mingle, so they create a billowing

cloak that drapes the summit of Table Mountain.

Spectacular though this is, the mountain's cloudy covering is only a hint of the

profound influence that these two very different

oceans have on the fortunes of life here.

And not just here at the Cape, but across the length and breadth of Southern Africa.

2,000 miles north from the Cape, beneath this sandy beach, new life is stirring.

Hundreds of baby green turtles emerge like a torrent from the safety of their nest.

Each one, just seven centimetres long, must make a 100-metre sprint down the beach.

From the moment they hatch, they're driven by an instinctive urge to run to the sea.

Few creatures start life with the odds for success so heavily stacked against them.

Yellow-billed kites.

Pied crows.

But so many of these hatchlings appear

together that predators can't catch them all.

Last out, this baby might seem doomed.

But struggling out late could just give her a chance.

The crows seem insatiable.

Even those that reach the sea aren't safe.

This female has to make a dash for it.

She's still in danger, and not just from above.

A ghost crab may be smaller than the hatchling,

but it has the strength to drag her into its lair.

Not this time.

At last, the sea.

She has to catch her breath if she's not to drown,

but the pounding waves make it desperately difficult.

CROWD MOVES CROWD MOVES CROWD MOVES

Beyond the surf, calmer water.

But even here, the hatchling is not out of danger.

She dives...

just in time.

Only one hatchling in a thousand will survive to adulthood.

But if she does, she may live for 80 years.

For now, the ocean is there to be explored.

As the hatchling disappears into the deep blue, she swims into the waters of one of

the planet's most powerful currents, the Agulhas.

The Agulhas sweep south towards the Cape, transporting

100 billion gallons of warm water every day.

These tropical seas are so warm, they evaporate on an enormous scale.

Water vapour rises until, at altitude, it cools and condenses into clouds.

As the clouds drift inland, they bring rain to

one of the least explored corners of our planet.

The mountains of Mozambique.

This is the wettest place in Southern Africa.

Decades of civil war have kept travellers away from this little-known land.

It was satellite mapping that revealed the full extent of the forest that grows here.

So now it's known to outsiders as the Google Rainforest.

It could also be called the Butterfly Forest.

After the rains, butterflies have emerged from their nests.

They merge together in huge numbers.

As soon as their wings dry out, they will take to the air.

Their goal?

To find a mate.

But how?

There may be thousands close by, but the foliage is

so thick, it's difficult for them to find each other.

They have a remarkable solution.

They follow rivers upstream and travel to higher ground.

The journey can take hours of determined flying.

Eventually, they emerge into the only open space there is.

The treeless peak of Mount Mabu.

Up here, free from the confines of the forest, they hold a butterfly ball.

Now the butterflies have all the space they need for their aerobatic courtship.

The male's strategy is simple.

Fly higher and faster than the competition and just maybe you'll win a virgin female.

This spectacular gathering, unseen by outsiders until now, happens for just half

an hour each morning and for just a few weeks in the year.

Once mated, the females descend back to the rainforest to lay their eggs.

A forest that only exists because of moisture rising from the warm Agulhas

current, hundreds of miles away in the Indian Ocean.

The rainwater now flows southwards from Mozambique's

highest peaks to the lowlands of the Eastern Cape.

And where the land flattens, rivers slow, creating a vast swamp fifty miles across.

This is Gorongoza.

Here, all kinds of creatures come to catch fish.

Whiskered catfish work as a team.

They take a gulp of air at the surface and then

belch it out under water to create a net of bubbles.

And that traps little fish.

There are fish for everyone.

And each species has its own technique for catching them.

It's all very well having a big beak, but you've still got to know how to use it.

This young pelican has a lot to learn.

And not long to do so.

Maybe, like the catfish, teamwork is the answer.

It's certainly working for the flock.

And this pelican seems to be getting the hang of it.

But surely it can't swallow that catfish.

Trying to was a mistake.

The rainwater briefly held in Gorongosa's

swamp has now been enriched with silt and sand.

All down this coast, sediment-laden rivers, the

Zambezi, the Limpopo, the Save, drain back to the sea.

And there they meet the Agulhas current.

And what happens to all that sand?

Over the millennia, the Agulhas has worked it into a complex underwater landscape.

This vast sand sculpture is the Bazaruto

archipelago, the oldest of its kind in the world.

It may look like paradise, but living here is not easy.

For a hundred thousand years, the Agulhas current has battered these submerged dunes

with underwater sandstorms.

But where the water is deep enough to escape these storms, nutrients carried

from Africa's interior fuel an explosion of life.

A rare oceanic hunter rules here.

Giant kingfish.

As big as a man, and weight for weight, one of the most powerful fish in the sea.

Despite their size, they're extraordinarily agile when hunting.

Normally, kingfish are solitary.

But for just a few weeks each year, they gather at places

like Bazaruto and prepare for an extraordinary journey.

One that will take them far inland.

The Ntentu River.

The king of kingfish leads them upstream.

As they travel further into freshwater, they seem to

change from aggressive hunters into dedicated pilgrims.

Now, many miles from their natural home, and in response to an unknown cue,

they stop and begin to circle.

Other marine fish that migrate upriver usually do so in order to breed.

But there's no evidence that these kingfish spawn up here.

Neither do they hunt.

So what are they doing?

In truth, the purpose of this strange behavior is still unknown.

Within a few weeks, they will retrace their journey back to the ocean.

The lives of kingfish, like those of turtles and butterflies and pelicans,

are influenced by the Agulhas current.

But that influence can only reach so far.

And this is why.

The Drakensberg Mountains.

Here, local people say that the vultures soar so high they can see into the future.

These sheer cliffs, rising to over 3,000 meters, hold back the advancing rain

clouds, and as a result, the land beyond them is starved of water.

This is the greatest expanse of sand in the world.

A seemingly endless desert that is the vast, parched center of Southern Africa.

Thousands of miles to the west, where this desert

meets the Atlantic Ocean, another current prevails.

But the Benguela current, surging up the west

side of Africa, has a very different character.

It's extremely cold, full of nutrients, and it's thronged with life.

A great white shark.

They can raise their body temperature to 10 degrees above that of the surrounding sea.

But doing so requires an enormous amount of high-grade fuel.

So this is the great bonanza for them.

The body of a dead whale.

The carcass will draw in every great white for miles around.

And here, off Cape Town, that means a lot of sharks.

Instead of feeding in a frenzy, these sharks have rather refined table manners.

They swim side by side to get the measure of each other.

Then each takes its turn.

This female is the biggest, so she eats first.

The next only feeds when she gives way.

The waters of the Benguela are so rich, they support more

great white sharks than any other seas on the planet.

And they are so cold, they attract some

surprising creatures to these African shores.

Penguins.

African penguins.

This female is returning to relieve her partner.

Of course, there's no ice here, but these rocks can be almost as slippery.

But there are more serious obstacles than the slippery rocks awaiting them.

It's his turn to feed, so he leaves her to look after their eggs.

Now she must tackle a problem faced by no other kind of penguin.

For the next ten days, she must protect her eggs from the African sun.

A dense coat of feathers that keeps her warm in cold seas now stifles her.

On these exposed rocks, she must shade her eggs instead of keeping them warm.

Everything here seems the wrong way round.

For some, the soaring temperature is too much.

A neighbor deserts his nest.

His egg will not survive.

He's not the only one to give up.

Some years, not a single chick is reared.

Penguins are adapted to withstand temperatures of 40 degrees below zero.

Not 40 degrees above.

Now, at the hottest part of the day, the very worst time, her chicks are hatching.

Just when they need her most, she's reaching the limit of her endurance.

After ten days of intensive fishing, the chick's

father comes back to take his turn at the nest.

But will he be too late?

He greets his young for the very first time.

The girl is now ready to go to the nest.

The coolness of the Benguela current brought the penguins here.

But that very coolness is a great

disadvantage because it generates little rain.

It can, however, produce moisture in a different form.

A thick blanket of fog rolls in from the sea and condenses on this thirsty lamb.

And each year, the desert bursts into life with a dazzling display.

Water is so scarce that this show will not last long.

So plants compete to attract their pollinators with color.

Here in Namaqua land, a 600-mile strip of

coastal desert becomes carpeted with blooms.

The morning sun opens a Namaqua daisy and reveals a male monkey beetle asleep inside.

Nights here are so cold that monkey beetles

shelter within the closed-up petals of the daisies.

The habit brings benefits to both sides.

The beetle is kept warm and the flower gets pollinated.

But now the beetle has urgent business.

He must find a mate.

As he searches, he hops from bloom to bloom, pollinating each in turn.

At last, he spots a potential mate.

A golden princess.

But here comes trouble.

A rival.

There's no time for introductions.

But

he's been too slow.

The rivals immediately begin to brawl.

The female will only mate inside the daisy.

So they wrestle for possession.

They're so engrossed in fighting, they've pushed her off.

The challenger is ejected.

The winner wastes no time before getting back to business.

At last.

Now, there will be a new generation of monkey

beetles to pollinate these Namakhmaland flowers.

For most of the year, this land is desperately dry.

But just occasionally, brief, violent storms sweep in.

From the cold ocean.

Springbok have been roaming this desert for many months.

Searching for one of these rare and highly localized downpours.

The grass is sprouting.

And that is worth celebrating.

If you're a springbok...

that means pronging.

We still don't know exactly why they do this.

The simplest answer is that they're dancing for joy.

Africa's most southerly tip.

This is where the two great ocean currents, the warm

Agulhas and the Gold Manguela, crash into one another.

And this collision, in itself, draws in life in abundance.

A superpod of hunting dolphins, 5,000 strong.

And shadowing them.

Because

biggest predator.

A brooder's whale.

This female is 15 meters long.

And weighs more than a whole family of elephants.

The dolphins are in pursuit of sardines.

Millions of them.

But these cold water fish are heading towards

an impenetrable barrier of warm water.

That they will not cross.

The Agulhas current.

They're trapped.

And that gives the whale her chance.

But the sardines are so speedy, that the whale only catches a few with each pass.

More and more hunters arrive.

The whale needs the other hunters to push the

fish upwards, forcing them against the surface.

Now they have nowhere to escape.

With each lumbering turn, she loses precious time.

Time that favors the more nimble.

The brooder's whale probably knows that this

opportunity will last less than five minutes.

And with the last few lunges, she finally cashes in.

The forces that triggered this great event have also shaped

the fortunes of life far beyond this particular battleground.

Without these currents, Southern Africa would be a desert.

But combined, the very different powers of the Agulhas and the Benguela have

transformed the Cape into a land where life can flourish.

The Komoro Islands, off Africa's east coast, are a haven for green turtles.

Every year, a million turtles hatch on these beaches.

But the chances of any one of them surviving is tiny.

Ah!

Ah!

The Africa team came here to try and capture the dramatic

first few minutes in the lives of these baby turtles.

It was to be both a technical and surprisingly emotional challenge.

It's only when you get down on the high level of the baby turtle that you realize

what an enormous journey it's got to make down over the beach.

And it really is quite epic.

That's nice.

Oh yeah, that's lovely.

It's using all of these complicated, heavy bits of equipment which hopefully

will enable us to get into the world of a turtle which is just a few inches long.

As they break out of all this soft sand, they hit the

hard sand, and that's where the real sprint takes place.

They must be desperate to hit that water because

you can see the seas just over the horizon.

We're following them all the way down and you do

kind of get involved with them and cheering them on.

Okay, slow down a bit.

Slow down.

And then suddenly all these crows come flocking in and start picking them off.

And you just think, that's just so unfair.

Lots more coming in, just loads coming in now.

And you've got to fill from them.

You know, it's really quite upsetting.

Particularly when you look through the camera and I'm

just filling a frame with a turtle running down the beach.

Then suddenly from nowhere, the beak comes in and that's it.

That turtle's no more.

The turtles that escape the perils of the beach still have to face pounding surf.

But at last, they're in their element.

More than can be said for the crew.

They're faster than you, aren't they?

Yep.

It's been embarrassing.

Beaten by something that's less than a day old.

When we saw hatchlings get off the beach and see them go

in the white water, you think they just get obliterated.

They just plunge through the water.

They do get flung around, but then they just frighten themselves, keep on swimming

and they're ahead of you, coming out the back of the wave.

And it's amazing.

You're seeing all these baby turtles getting picked off left, right and centre,

but they just keep going.

They are just so resilient.

And that made what happened next so distressing.

A particularly high spring tide flooded the beach.

Any baby turtles still in their nest would be lucky to survive.

See it bubbling out as well?

Yeah.

Well, it means that basically anything below that line is going to be gone.

Let's hope and pray it's not, but...

As you say, we don't know.

Let's go and see.

All across the world, turtles are in decline.

Their eggs are stolen.

The adults are hunted for their flesh.

And they drown in fishing nets.

But here in the Comoros, they have friends.

It's amazing hearing it, Samir.

It's just a really heartening story of how the local people

are doing everything they can to protect sort of what they can.

And what they think of as their turtles.

And some of the baby turtles have survived the flood tide.

I've already found two baby turtles in the nest.

One, two, three, four, five.

We followed them in the nest and helped them get out.

To help this village, we have to protect the little turtles and the big turtles.

Three.

They're pulling up us.

The whole village comes to help the hatchlings.

But the most important effort is to protect the adults

from outsiders who would hunt them for their meat.

They've taken it upon themselves to really police the beaches

around here and make sure that poaching is kept to a minimum.

The selfless protection these people provide means that this is one of the few

places in the world where turtle numbers are actually increasing.

And remarkably, here in Nizamiya, the population

has in fact doubled in the last decade.

As the shoot was coming to the end, cameraman Kevin Flay noticed that some of

the turtles that made it through the surf faced one last danger.

I'm getting shots of a kite which is flying

down and taking turtles off the water surface.

That was a part of the story we had to tell.

The aim is for us to be underwater, looking straight up as this happens.

And that's actually really quite hard.

Okay, three, two, one.

Undeterred, the crew got into position.

There we go, the kite's up.

You can't see where you're going because my head's glued to

this viewfinder so I'm banging into rocks and things like that.

I'm really just trying to keep the turtle in shot.

Something came in then?

It actually came in and swooped down over the water's surface.

And you could see the kite from underwater?

I could see it, I could see the shape.

In frame and you were running?

Yeah.

Didn't take the turtle?

Didn't take the turtle.

Probably that's the best of both worlds because we got our

lovely underwater shot of a kite and the turtle gets away.

This lucky hatchling isn't the only one.

With the help of the village of Itsamia, thousands

more have a chance to make it to the open ocean.

There's only really local populations that can

actually support and sustain this conservation work.

If it comes from the roots upwards then it's got a chance to survive.

I think it's amazing, I really do, the fact that they do

this and I wish you see it more often around the world.

It's hard not to admire these extraordinary

little creatures as they battle against such odds.

This baby turtle won't touch land again until she

returns to the very same island to lay her own eggs.

With luck, she'll find the beaches still protected by the people of Itsamia.