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DAVID ATTENBOROUGH: The Cape of Good Hope,
On Africa's most 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.
(WAVES CRASHING)
And not just here at the Cape,
but across the length and breadth of southern Africa.
Two thousand miles north from the Cape,
beneath this sandy beach,
new life is stirring.
(SCURRYING)
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.
(SQUAWKING)
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.
(CROWS CAWING)
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.
(WAVES LAPPING)
She has to catch a breath if she's not to drown.
But the pounding waves make it desperately difficult.
(WAVES CRASHING)
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 the planet's most powerful currents,
the Agulhas.
The Agulhas sweeps 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.
(THUNDER RUMBLING)
This 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.
(BIRDS CHIRPING)
It could also be called the butterfly forest.
After the rains,
butterflies have emerged 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.
(BIRDS TWITTERING)
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 *** 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 rain water 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 50 miles across.
This is Gorongosa.
Here, all kinds of creatures come to catch fish.
(WATER BUBBLING)
(SQUAWKING)
Whiskered catfish work as a team.
They take a gulp of air at the surface
and then belch it out underwater 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.
(SQUAWKING)
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.
(SQUAWKING)
Maybe, like the catfish, teamwork is the answer.
It's certainly working for the flock,
and the young pelican seems to be getting the hang of it.
But surely he'll never swallow that catfish.
Trying to was a mistake.
(CROWS CAWING)
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.
(WAVES ROARING)
For 100,000 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 Mtentu River.
The king of the 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 behaviour 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 metres,
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 centre 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.
(SEALS BARKING)
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 a 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.
(WAVES CRASHING)
And they are so cold
they attract some surprising creatures to these African shores.
(PENGUINS WARBLING)
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.
(WARBLING CONTINUES)
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 10 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 neighbour 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.
(PENGUIN CHICK PEEPING)
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 10 days of intensive fishing,
the chick's father comes back to take his turn at the nest.
But will he be too late?
(CHICKS PEEPING)
(FEMALE PENGUIN BLEATING)
He greets his young for the very first time.
(CHICK PEEPING)
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.
(RUMBLING)
A thick blanket of fog rolls in from the sea
and condenses on this thirsty land.
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 colour.
Here in Namaqualand, 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.
(WINGS WHIRRING)
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 Namaqualand flowers.
For most of the year, this land is desperately dry,
but just occasionally, brief, violent storms sweep in from the cold ocean.
(THUNDER RUMBLING)
Springbok have been roaming this desert for many months,
searching for one of these rare and highly localised downpours.
(THUNDER RUMBLING)
The grass is sprouting.
And that is worth celebrating.
If you're a springbok
that means pronking.
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 cold Benguela, crash into one another.
And this collision in itself draws in life in abundance.
(DOLPHINS CHATTERING)
A super-pod of hunting dolphins 5,000 strong.
(DOLPHINS WHISTLING)
And shadowing them,
Africa's biggest predator,
a Bryde's whale.
This female is 15 metres 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.
(DOLPHINS WHISTLING)
They're trapped.
And that gives the whale her chance.
The sardines are so speedy
that the whale only catches a few with each pass.
More and more hunters arrive.
(BIRDS HONKING)
But 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 favours the more nimble.
The Bryde'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.