From out at sea the ancient sailors could smell the approaching land,
the scent of rivers and swamps.
...but Africa was already beneath them.
The oceans are vital to Africa.
...They control the destiny of the land...
allowing wildlife to thrive in the most unexpected places.
This is a story of living on the edge.
An epic journey along Africa's greatest frontier.
Africa is an island...
washed by warm and cold seas...
Nowhere is the contrast more extreme than at its southern tip.
This is the Cape of Good Hope,
where Africa faces the Antarctic.
Here are animals few would associate with warm Africa...
...like penguins... and fur seals.
Life thrives in these icy waters...
rich in nutrients... rising from the deep.
Sardines feast on the prolific plankton...
In turn these shoals support hunters from the sky.
Every year nearly 200,000 gannets gather off the coast of South Africa
to raise their young.
The chicks are about to learn to fend for themselves,
after months of being fattened on the plentiful fish.
Now they must take the first step to independence.
But they face a huge challenge...
making their maiden flight on Africa's stormiest coast.
So they join other trainees in "flying schools"...
tip-toeing on the cusp of flight...
...revving up into the wind... building muscles...
Making the first flight isn't easy...
...many are overwhelmed by the raw power of the ocean...
This wasn't the plan...
being thrown in at the deep end.
Here at sea level it's harder to take off...
the wind is around and above them... not beneath them.
...but the rough sea is the very least of their problems...
Fur seals are clever predators.
Normally fish-eaters,
they've learned to seize this rare feast...
But soon the chicks are soaring above the jaws of danger.
These southern waters teem with life...
and they also provide for the land.
Cold, damp air, rising off the ocean, flows across the Cape.
Here at the end of Africa the influence of the ocean causes unlikely encounters.
Ostriches. Birds who can survive the hottest deserts relish the cool breeze...
and a refreshing paddle.
But the sea provides much more than this...
...for those in the know.
In summer Chacma baboons struggle to find enough food on land.
They've learned to keep an eye on the sea.
Baboons know that at low water there are riches among the rocks.
Exposed by the retreating tide, a favourite prize... limpets.
With their strong canines and dextrous thumbs the baboons
can harvest this protein-rich seafood meal.
But on a very low tide,
baboons have discovered there's an even
better meal to be had -right at the water's edge
concealed among the weed.
A shark egg!
The eggs, hidden in their purses,
should be safely camouflaged here...
were it not for this keen-eyed and intelligent primate.
Monkeys eating sharks...
who would have thought it possible?
This delicacy is a rare treat...
only available at the turn of a spring tide.
The ocean is quick to reclaim its territory.
With the sea's return, great forests of kelp sway into life.
Kelp is the world's largest and fastest growing algae...
it thrives on nutrients churned up by these cold, rich waters.
Anchored firmly to the rocks,
kelp is built for heavy weather.
It's just as well...
these are the roaring southern seas.
Further east there is a new frontier where the waters are warmer...
...it's a mecca for surfers.
Bottle-nosed dolphins!
Southern Africa's coast has such magnificent variety
because it's the meeting place of two powerful currents:
A cold one and a warm one.
To the West, the cold Benguela current...
rising from the bottom of the Atlantic...
And from the East, the powerful Agulhas current...
a great warm river in the ocean sweeping down from the equator.
Here in East Africa, for over 30 million years,
the Indian Ocean has brought moisture to the land...
supporting thick swamps and forests.
From as far away as Portugal and China ships
came to these green shores
lured by the promise of trade and conquest.
They came riding on the monsoon winds.
Winds, which twice a year carry the promise of rain.
Far out on the Indian Ocean the tropical heat
causes sea water to evaporate and rise.
The clouds steadily build.
Strong easterly winds hurl them against the land
where they shed their load.
This belt of coastal forest nurtures animals
found nowhere else in the world...
Like the Zanzibar red colobus.
These treetop monkeys are specialist leaf-eaters,
able to digest a whole range of plants.
Though they spend most of their time high in the canopy,
red colobus sometimes venture into a very different world...
Here on the margins of the Indian ocean is a mysterious forest
with its roots in sea water.
The mangrove swamp.
Mangroves are pioneers from the land, gradually encroaching on the sea.
They can survive being submerged in salt water
at high tide and being blasted by the sun at low tide...
...they also provide a feast for sea creatures... Crabs...
the most successful invaders...
Soldier crabs emerge on the falling tide
to harvest microscopic algae from the rich mud...
Other crabs specialise in leaf-eating.
Fallen leaves feed most of the mangroves' inhabitants,
but competition is fierce.
And if you don't want to wait around for your leaf to fall,
you need to be bold and go to the source of this bounty...
...which is what the climbing crabs of East Africa do twice a day... everyday!
At dawn, before the sun is too hot, the crabs start climbing.
In human terms it's the equivalent of scaling a thousand metre cliff.
But it's worth it.
Once on top,
the crabs can munch away to their hearts' content...
scratching on the underside of tender young leaves.
Up here they are not alone...
red colobus also like young mangrove leaves...
With the heat of the day now rising...
the colobus rest and digest,
but the crabs can't afford a siesta:
They might die of dehydration.
Still dependent on the sea for moisture, they're only visitors to the canopy.
Nesting in amongst the roots of the mangroves,
a strange creature...
The mudskipper.
Not so much a fish - but "half a fish".
Mudskippers fear the water... for it's full of predators...
so when the tide floods in it's time to take drastic action.
These fish can even climb trees and breathe out of water...
perfectly suited to this strange frontier of land and sea.
...On this coast of pioneers, people are the most recent...
From here the early Arabs traded in slaves,
precious metal and spices.
For more than 2000 years
humans have exploited the reversal of the monsoon winds.
For six months they blow north... then they turn south...
ferrying traders and fishermen up and down the coast.
North of the tropics is a land of burning shores.
Around the Horn of Africa is a sea trapped between Africa and Arabia,
a small turquoise jewel separating desert from desert...
the Red Sea.
This enclosed sea gets hardly any rain...
and evaporation is intense in the dry heat.
Its waters can only refill from the Indian ocean,
rushing through a narrow passage...
a place of powerful currents.
Here in the Bab el Mendeb strait,
life has adapted to the racing current.
Soft corals and weeds bend with the flow...
Red-toothed trigger fish are streamlined,
intercepting plankton as it flushes past.
And through the narrow straits come ghostly invaders from the Indian ocean...
Devil Rays!
In the heart of the Red Sea, in calmer water,
chevron barracuda can relax.
Hunters by night,
this great barrel of silver is a resting formation.
The Red Sea waters are crystal clear.
On this desert coast there's no silting from rivers...
it's warm water... full of light...
...perfect conditions for the growth of coral
and the empire of colour it supports...
...like the Leopard moray...
...fluorescent coral...
the clown fish and its anemone.
Every year the monsoon winds turn this Bay in Sudan
into a great plankton trap.
Manta Rays - giant filter feeders gather from miles around,
forming long chains...
By swimming in formation...
like a flock of birds,
with each slightly to the side of the one in front,
the mantas can best filter the water...
The leaders peel away and join the back of the queue in a circle of feeding.
The manta is one of the largest living fish
over a tonne in weight and seven metres across... huge...
but gliding with a ballerina's grace.
In the giants' wake...
little fish feeding on any leftovers.
And following them are other hunters.
The Red Sea allows ospreys to survive on Africa's most barren shores.
But barren land isn't necessarily dead land.
Africa and Arabia are steadily drifting apart...
and as they do the Red Sea is growing wider...
opening up at two and a half centimetres a year.
...Along its margins are giant cracks,
where sea water flows deep underground and is heated by a volcanic furnace.
Here in Djibouti the seawater emerges far inland...
...under a fierce sun it quickly evaporates leaving salt.
Over time Lake Asal has formed a gigantic crust
that's visible from space.
Pure marine salt is precious...
For thousands of years it's been mined by one of Africa's hardiest peoples.
The Afars of Djibouti.
The Afars trade this important commodity
with the people of the Ethiopian highlands.
The Red Sea is Africa's youngest sea.
These alien towers bear testament
to the violent geological forces still at work.
Millions of years ago this was the land bridge
between Africa and Europe...
...The threshold across which life flowed, including our own ancestors.
Now Africa sits apart...
and is once again pushing its northern coast towards Europe.
Gradually the Mediterranean sea is shrinking.
Millions of years from now it may even vanish...
like the ancient civilisations of the North African coast.
Imperial grandeur drove out much of wild Africa.
The big mammals may have gone,
but birds like Eleonora's falcon,
named after a Sardinian Princess, still endure.
The falcons breed in colonies hundreds strong...
and it takes a lot of prey to support them.
So they delay their breeding until September to coincide
with an extraordinary migration.
Millions of migrant birds flocking to tropical Africa
for food and warmth in winter are targeted by Eleanora's watchful squadrons.
Hunters of the sea wind.
The swiftest of killers,
these small falcons are also nurturing parents.
The chicks need large amounts of fresh food...
up to three birds a day.
Many small birds do fall prey to the Falcons,
but most escape to face an even greater challenge.
They must skirt the parched sands of the largest desert on earth
the mighty Sahara as they fly south along the Atlantic seaboard.
This is a marathon journey.
But there is the odd pit-stop along the way.
Here in Mauritania the waders willingly seize what people throw away...
The lmraguen fishermen live in a sun-blasted desert wilderness.
But this place is more fertile than it looks.
The nets fill with fish thanks to a cold upwelling in the Atlantic.
But what really draws the migrants to this coast... is this...
a vast mudflat where the Sahara meets the sea...
...the Banc D'Arguin National Park.
Nearly two million birds fly in to winter here.
Both locals and visitors crowd these deserts shores.
These mudflats are rich in worms and shellfish.
Some birds will have lost half their body weight
on the long flight south from Europe.
With no fat reserves left, they feed frenetically.
As the tide returns the land shrinks and the birds swarm in dazzling numbers.
But the little birds have been followed...
Marsh harriers are also migrants... shadowing the flocks...
But hunting isn't easy.
In skies crowded with wings it's hard to zero in on a target.
There's safety in numbers!
To the south of this desert coast is a moist tropical shore.
The seas of equatorial West Africa are heated by the Guinea current,
which throws up endless cloud from the ocean.
It's the wettest part of Africa!
Up to five metres of rain a year.
The land is scoured by mighty rivers like the Congo and the Niger.
They drain vast areas flushing sediment into the sea.
Leaving the waters warm, but murky...
And upon these sandy shores,
growing right down to the water's edge,
is the largest rainforest in Africa.
It's a frontier for some familiar faces.
But it's also home to more unlikely characters
Hippos live among the mangroves,
their skin able to tolerate the brackish water.
They'll sometimes even use the sea to reach new feeding grounds along the coast.
The beaches of Gabon's Petit Luango National Park
also draw elephants from deep in the forest.
After years of persecution for their ivory,
these shy animals are now protected.
They're good swimmers and easily navigate the thick mangrove swamp.
Here on the edge of the steaming forest
the elephants can enjoy the cool ocean breezes.
Their forest diet lacks sodium,
so they also comb the beach for salty creepers
and the Borassus palm fruit... a coastal delicacy.
Red River Hogs are normally secretive forest animals.
Pigs on the beach!
They've even been known to dig out turtle eggs!
Even buffalo visit the shore to get relief from the forest's mosquitoes and ticks...
...though there's still a few left for the oxpeckers.
This is a coast where life is controlled by a warm current...
Heading south the waters change character...
once more entering the embrace of the cold Benguela current.
From the wettest place in Africa... to one of the driest...
the Namib desert...
two million square kilometres of sand...
where the cold ocean offers little evaporation,
starving the land of moisture.
The Skeleton Coast...
a graveyard of ships lost in fog and wild seas.
This is a coast of extremes.
Desolate shores, but crowded with life.
Cape Cormorants are among the many animals drawn here
by an ocean brimming with fish.
They're joined by a young fur seal,
perhaps mistaking all the black shapes for others of its kind.
The sight of Cormorants living on the edge of the desert
is surprising enough...
but the fishing here is so good...
even penguins will tolerate the baking shores.
These fishing birds are more at home in sub-polar regions,
but can survive in Africa thanks to the cold sea.
But there's a price to pay for living so near the Equator.
Temperatures can soar to forty degrees Celsius.
The parents take it in turn to stick it out on the nest!
A sheltering wing against the powerful sun.
The desert coast hosts a far larger tribe of colonists - Cape Fur Seals.
Tens of thousands come here to breed.
In the space of a few weeks all the females give birth.
The bond between mother and pup is strong,
they recognise each other by smell and sound.
But this noisy colony draws attention from inland
...Brown hyenas are normally shy scavengers,
but the arrival of so many animals
in their desert territory turns them into bold hunters.
The seals have no defence against such a powerful interloper.
New-born pups are easy targets and not just for hyenas.
Black-backed jackals are also on the prowl.
But there is a far greater danger here.
Some days the cooling ocean wind stops... the coast becomes a furnace...
Wrapped in fur and blubber, the seals suffer.
The mothers become increasingly desperate.
They head for the sea to cool off, some dragging their pups with them.
They're shadowed by hungry jackals.
Though this treatment seems rough, it is key to the pup's survival.
The mother takes him to the water's edge.
He can't swim, but he'll be cooled by sea spray...
...while his mother swims in the sea!
But not all mothers are so experienced.
Other females at the top of the colony,
irresistibly drawn to the sea, now abandon their pups.
Alone and exposed at the edge of the desert,
the pups are very vulnerable.
Fur seals are designed for the sub-Antarctic,
not the desert, and the pups' black coats are a real problem.
They absorb the scorching heat.
The pup is too young to swim and too inexperienced
to find shade on its own.
Refreshed by the seas, the mothers head back to their pups.
For some... it is too late!
Not all pups have succumbed.
Some found refuge from the heat...
...and by scent and call are eventually reunited with their mothers.
And in just a few weeks the pups are old enough
to enjoy the refreshing water for the first time.
Adult first seek spend most their life is on the sea
fishing the rich current from Nambia to the Cape of Good Hope.
Down towards Africa's southernmost tip,
the seas again explode with life.
But as seals are drawn to the rich fishing here,
so others are drawn to them...
The Great White Shark
Africa's largest and most powerful predator...
Over millions of years it's evolved a unique hunting ability.
It powers from the deep like a missile.
It is a lethal encounter...
but these fertile oceans support vast numbers of seals and predators
have little impact on the whole population.
The seas that wash against African support life
in the most surprising places.
Bringing rain to forests and relief to deserts.
They also carve out the familiar shape of the continent.
From the shores of the Sahara right down to the Cape of Good Hope,
the mighty oceans determine the very nature of Africa.