Narrator: In the heart of Africa is a river of legendary power, a river of constant transformation.

Creator of Victoria Falls, the largest curtain of water on earth.

Carving through solid rock, rearing up into some of the world's most treacherous rapids.

Spreading out to fill vast lakes.

Fueling some of Africa's greatest gatherings of wildlife.

This river changes dramatically through the seasons... [Thunder] shaping all life to its rhythm... creating challenge and opportunity.

[Elephant trumpets] This is the Zambezi, Africa's mighty shape-shifting river.

Earth's great rivers... make extraordinary journeys... carving through continents... feeding and connecting life... nurturing culture... providing a place for adventure.

From the frozen wilderness of the Yukon... to the tropical heat of the Zambezi... [Hippo growling] and the magical, hidden worlds of the Danube... rivers are the lifeblood of planet Earth.

♪ [Birds chirping] Narrator: In a far corner of Zambia is a forest... a sacred place.

The Lunda people call it "yam-bey-shee," the "heart of everything."

Here, a clear spring bubbles to the surface... the source of the Zambezi, a tiny trickle on the start of an epic journey.

The Zambezi is one of Africa's mightiest rivers.

It flows from its source in the heart of the continent for 1,500 miles, traveling through 6 different countries on its course to the Indian Ocean.

But to become one of Earth's great rivers, it must overcome many obstacles, transforming into a river of extremes.

Its first challenge starts as soon as it leaves the forests of its birth.

Just as its waters get going, it runs into trouble.

Barotseland.

An endless, flat plain in the far west of Zambia.

So flat, the Zambezi completely loses momentum.

And it's September, the peak of the dry season.

Its waters are evaporating under the heat of the African sun.

[Birds squawking] But it's just now that the Zambezi is vitally important, especially for the people that live here, like cattle farmer Makalo Makaulo.

Makaulo: September is the hottest time in the year, where everything is dried out.

I tell you we are suffering because we depend on water.

Here in Batoseland, everything depends on water.

Narrator: Every day in the dry season, to keep his cows alive, Makalo Makaulo must take them from the arid grasslands to the Zambezi's life-giving waters.

Makaulo: Zambezi River, it's like a--a father to me, the father who feeds his children.

The parent of Barotseland is the Zambezi.

Narrator: But as the heat intensifies, the Zambezi's waters are receding... leaving miles of dry, hot river bed... a challenging place, whatever your walk of life.

[Boy speaking native language] Narrator: But there are advantages to the dry season.

[Children shouting indistinctly] [Mwangala speaking native language] Narrator: For school boys and cattle farmers alike, life goes on through the dry season... as it does for the wildlife here.

These vast plains are home to some of the greatest concentrations of wildlife anywhere in Africa... and this is their toughest time.

But the heat can only build for so long.

[Thunder] It's now October and a change is coming to Barotseland.

Over 30,000 wildebeest are on the move.

[Wildebeest grunts] They are heading for the calving grounds in the south of the plains in anticipation of the rains.

At last, 6 months of drought is coming to an end.

[Thunder] When the rain is coming, everything is changing.

Narrator: In October every year, tropical rains push down from the equator and spill over into Barotseland.

[Wildebeest grunts] [Thunder] This is what all the inhabitants have been waiting for.

Makaulo: So, when the rains come, our hearts are feeling very happy because we are expecting good things to come.

♪ I don't know how even to express it, because everything there, even the-- the nature of the land is changing.

Narrator: The effect of the rain is miraculous.

A greening of the land over 7,000 square miles that can even be seen from space.

My God, why can't this period be like that always?

Narrator: As the grasslands are revitalized, they become a globally important wetland, supporting 350 species of birds.

And finally, the wildebeest arrive at their calving grounds.

[Wildebeest grunting] Over just a couple of weeks, all the herd's calves are born to coincide with this time of plenty.

[Frogs croaking] [Birds squawking] But the rains are having an even more dramatic effect on the Zambezi River.

They bring its first great transformation.

It starts to flood.

♪ [Mwangala speaking native language] Narrator: The people of Barotseland have always lived in tune with the annual flooding of the Zambezi.

Larger villages are built on high ground so they stay dry during the flood.

But many smaller buildings are designed to be submerged for a while... abandoned for 4 or 5 months until the waters subside.

The rising waters bring new challenges.

[Mwangala speaking native language] Narrator: Most children have to stop going to school in the wet season... but this school has been built with flooding in mind.

Set on a mound of high ground, it even has docks for the pupils to tie up to.

So long as they can brave the school run, Gift and his classmates can keep learning while the waters keep rising.

[Cattle mooing] Cattle farmers don't have the option of staying in the flood plains.

They now take to canoes to swim their cattle to higher ground.

[Cattle mooing] But beneath the waters, the land is being fertilized by the Zambezi's silt.

So when the cattle return, they will have some of the most nutritious grass around.

The floods are not only good for the inhabitants of Barotseland.

The waters of the entire flood plain are now gathering into one rejuvenated flow.

The Zambezi is on the move again.

Heading out of Barotseland, the Zambezi now turns east, where, for the next 300 miles, it will form the border between Zambia and Zimbabwe.

Boosted by the water from upstream, the Zambezi grows... [Hippo growling] and as it grows, it brings more opportunity for life.

The Zambezi is starting to look like a great African river.

As it flows over a series of steps in the bedrock, it starts to gather pace.

In the distance, a cloud of mist is rising.

A hint of what is to come.

Right at the point where the Zambezi reaches its maximum power... the entire river flows over a cliff.

Over a mile wide.

Falling for over 300 feet.

100 million gallons of water per minute.

So much water, it creates a plume of spray that rises over 1,000 feet into the sky... giving it the name of Mosi-au-tunya, "The Smoke That Thunders."

This is Victoria Falls... the largest curtain of water on Earth.

♪ You would think it's a place to steer well clear of, but there is temptation here.

A group of male elephants have come down to the edge of the river.

At this time of year, the islands right above the falls are lush with tasty vegetation, an elephant's paradise.

But to reach them is dangerous.

The Zambezi in full flood is a formidable force, and this is not the place to get swept away by the current.

But the lure of the islands is strong.

These males are prepared to take the risk.

[Elephants trumpeting] The further they go, the stronger the current gets... and now it's getting deeper.

[Elephant trumpeting] They are forced to swim.

Immediately, the current starts to drag them downstream.

They need to reach an island, or they could get swept over the falls.

♪ One by one, they find their footing.

[Elephant trumpeting] But for smaller elephants, the danger is greater.

♪ At last, they are all safely across.

And right away, they start feasting on their prize of rich vegetation.

But elephants can eat 500 pounds of food in a day.

So, they'll soon get through all the tastiest pickings here... and will have to take their chances with the Zambezi all over again.

Victoria Falls marks the next great transformation for the Zambezi... as the entire river is swallowed up by a great chasm in the Earth.

Trapped in a channel just 100 feet across, the Zambezi now carves down through the rocky heart of Africa... forming sheer walls over 400 feet high.

This is the Batoka Gorge, and it's here that the Zambezi conjures up another phenomenon... less well known than Victoria Falls, but just as unique.

The Zambezi wave.

Surf perfection for those brave enough to try it.

Man: It's crazy that you can bring something like surfing here.

Narrator: Mikey February is a professional surfer.

He's here, 600 miles from the nearest ocean, to surf the Zambezi wave.

February: It's once in a lifetime and only a few people have actually done it, and I think that's, you know, one of the most special parts of actually coming here.

Narrator: Mikey has come to the Zambezi at a key point in the year.

As the dry season returns, over a period of 3 or 4 months, the river changes again.

Victoria Falls starts to switch off.

Every year, the Zambezi goes through these dramatic cycles... with 50 times less water flowing over the falls when it's dry.

It's as the water levels in the gorge start dropping that conditions become just right for surfing.

When the water gets low enough, it starts to interact with a unique rocky shelf on the river bed and forms the Zambezi wave... a wave that stays in exactly the same place and breaks continuously, but only lasts for 10 days.

And you've got to get to it.

The only way in is down some of the wildest rapids on Earth, made worse by the dropping water levels.

For Mikey, it's now or never.

Man: Whoa, whoa, whoa.

Whoa.

♪ Narrator: The journey in is just the beginning.

Even for a pro like Mikey, the Zambezi wave is not to be taken lightly.

You have rocks, you have, you know, hectic rapids, and the water is moving in such a different way to the ocean.

The fear factor is quite high.

♪ Narrator: Because the wave is formed by a slab of rock just beneath the surface, surfing it is dangerous.

And then...there are the rapids.

♪ Mikey needs to get out of the white water as fast as he can before he gets swept downstream.

He paddles for the pick-up point on the river bank, but the current is too strong.

This is where his experience in the water comes in.

He keeps calm.

And the safety kayaker is immediately on hand to help guide him out of trouble.

♪ Mikey is keen to try again.

February: The Zambezi wave is pretty much like catching an ocean wave but in reverse, because the ocean's pushing you forward and the river's obviously going the opposite way.

It's just a completely different experience.

Once you get it the first time, then you actually, you kind of get a gauge of what you should be doing.

And you kind of know exactly what to expect when you fall.

I do get scared surfing this wave.

It's like a balance of, like, surfing, survival mode, surfing, survival mode kind of thing.

I think the more time you spend in the river and on the wave, you learn new things about it.

The way it moves and noticing its, you know, little subtleties.

It's also so beautiful, you know, obviously you get to surf this wave, but you also get to appreciate the Zambezi and everything that it has to offer.

♪ Narrator: From the gorge, the Zambezi journeys on... winding its way through the fractured land along the border between Zambia and Zimbabwe.

But it's about to shape-shift once more... this time at the hands of an entirely different force.

Kariba Dam.

Built in the 1950s, it completely blocks the Zambezi and forces it to flow through its turbines to make electricity.

It took just 5 years for the river, held back behind the dam, to rise over 300 feet... forming the vast Lake Kariba, 25 miles wide, 140 miles long, 44 cubic miles of water.

So much water that it caused over 20 large earthquakes as it settled down on the land beneath.

By volume, Lake Kariba is the largest man-made lake on the planet.

But it has also become a haven for wildlife.

Along the lake's shoreline, rich grasslands have grown up.

And in the forests of drowned trees formed by the rising waters is a unique habitat perfect for the Zambezi's most iconic bird... the African fish eagle.

♪ [Bird squawks] There are around 500 breeding pairs here.

[Eagle calling] Each pair mates for life.

[Eagles calling] The contorted shapes of the trees providing a safe platform for their nests protected by the crocodile-infested waters below.

The trees also provide the perfect vantage point to survey the lake for prey.

On wings 6 1/2 foot across, they hunt for fish in the shallows.

♪ This place is so good for fish eagles, it has become their stronghold... their haunting call, the sound of Lake Kariba.

[Eagle calling] The Zambezi is now at the halfway point on its journey to the Indian Ocean.

As its waters break free of the great dam, the river flows on... and now it enters a lost world... spreading out into a valley 50 miles wide... nurturing a vast wilderness... some of the richest wildlife habitat in Africa.

[Elephant trumpets] It has also become world-famous as one of the places to come and watch wildlife.

This part of the Zambezi and its tributaries is dotted with safari lodges... places where people can come to meet the Zambezi's iconic animals.

♪ But who's watching who?

This safari lodge has operated for many years, and the wild animals are now used to people.

And there's one big attraction, just beyond the lobby.

A wild mango tree.

Its fruit is ripe for just a short time right at the end of the dry season.

A mouth-watering treat when food is scarce.

But it's not just baboons that have a thing for mangoes.

There are larger guests about to check into this lodge.

♪ Elephants have been coming to this mango tree from the river nearby for generations... following ancient pathways that existed long before the lodge was built.

One family in particular has learned that the lodge and its inhabitants poses no threat.

[Elephant trumpeting] Why go around... when you can walk right through reception?

These are completely wild elephants, but over the years, they have developed an understanding with the staff here, a trust passed down through elephant generations.

We've definitely developed that relationship, and we've seen youngsters grow into almost adults now over the years, so, it's--it's-- it's a beautiful relationship we have.

Narrator: This young bull probably first followed its mother through here as a calf.

[Elephant vocalizes] Now he is so relaxed, he even takes time to browse the gift shop... and check in at reception.

[Elephant snuffles] But soon the lure of the mangoes is too great.

Trees like this are vital for wildlife here.

Their roots draw water from deep underground, so they can fruit even in the dry season.

An excellent source of energy and vitamin C. And while the elephants are feasting, the guests get a wild encounter of a lifetime.

When the elephants have had enough, they quietly leave... the same way they came in... [Elephant vocalizes] straight through reception.

[Elephant vocalizes] [Snuffles] [Animals vocalizing] Elephants are big eaters, but they also drink over 50 gallons of water a day.

And for that, like all animals here, they rely on the river.

[Birds squawking] But the Zambezi is not only a place to get a drink.

For Carmine bee-eaters, the banks of the river provide the perfect place to make a home.

Their colonies can contain up to 1,000 nests... each one dug into the sandy cliff-face over a yard deep, where their eggs are protected from predators.

But outside the nest, the adults are vulnerable.

♪ African fish eagles don't only live on Lake Kariba, they can be found all along the Zambezi.

The skills that make them so good at catching fish work just as well for birds.

♪ Hippos spend the hot days wallowing in the Zambezi's cool waters.

"Schools" of females live together in a territory ruled by a single male, and for the most part, they are peaceful creatures... until the male's authority is challenged by a rival.

♪ Then hippos turn violent.

♪ [Hippo growling] In the safety of the river, hippos are all powerful.

It's as the sun goes down that they start to lose their bravado.

Hippos eat grass, about 100 pounds every night.

They can't get that by staying in the river.

They may be huge, over two tons, but out of water, they become cautious.

So, what are they nervous about?

As the night progresses... they travel further into the shadows... over 3 miles a night, not making a sound.

Soon, the hippos are peacefully grazing in moonlit meadows.

But they are being watched.

Lions.

♪ A pride of lions patrol this stretch of the Zambezi.

They know that animals are moving to and from the river and the dark is their friend.

But would they be bold enough to bother a two-ton hippo?

It's when the hippos start heading back to the Zambezi that they are at their most vulnerable.

Lions have formidable eyesight.

As the night gets darker, they gain the advantage.

Now anything is fair game.

[Lion growling] A female lion tries for an impala.

[Lion growling] Alarmed by the chaos, hippos scramble for the safety of the river.

But a young hippo is on its own.

That doesn't go unnoticed.

A male lion is onto it.

♪ Just in time.

The hippo makes good its escape.

Safe once more in the waters of the Zambezi.

As the Zambezi journeys on... it performs a last great feat of transformation.

Flowing down onto the coastal plains of Mozambique... it spreads out into countless, sinuous branches... forming a great triangle that reaches all the way to the Indian Ocean... the Zambezi Delta.

But this last chapter of the Zambezi's journey is haunted by the past.

From 1977 to 1992, this place was ravaged by civil war.

The human cost was immeasurable... and it had a devastating effect on wildlife.

Woman: During that war, wildlife was killed for the meat but also were killed for their ivory.

For example, elephants.

Everything just declined drastically.

Narrator: Dominique Goncalves is a Mozambican conservationist who is passionate about forging a brighter future for the wildlife here.

She is part of a team tasked to go into the heart of the Zambezi Delta to find out what has happened to the wildlife there since the devastation of the war.

Dominique is an elephant specialist.

Her plan is to put satellite collars on key elephants to understand their movements, a first step in protecting all the wildlife of the delta.

Goncalves: If you protect the area that an elephant uses, you're also protecting a huge area that many, many other species are using.

Narrator: But first she has to find them.

The Zambezi Delta is vast.

120 miles across, over 4,500 square miles.

Once, the delta was world famous for its extraordinary wealth of wildlife.. great herds of elephant and the largest numbers of buffalo in Africa.

Since the civil war, few studies have been conducted here, so, little is known about what is left.

But after just half an hour's flying, there's an encouraging sign.

Elephants.

Goncalves: You really have to assess which individual we can work with.

So, we have to think about the age and if it's a female, is she very, very pregnant or not?

Does she have a young calf or not, so you don't want to put an extra stress on her.

Narrator: The dart contains a fast-acting sedative.

And by the time the helicopter has landed, the elephant is already asleep.

A quick check on its breathing and they get to work.

They must work fast.

Though the elephant is sleeping peacefully, the quicker they are, the quicker it can return to the herd.

While the vet is fitting the collar, Dominique gathers as much information as she can.

This is a rare opportunity to study these delta elephants.

Blood samples... Goncalves: Her feet is very small.

Narrator: foot size, and a record of exactly what it feeds on is a crucial but less glamorous part of the job.

All completed in just 15 minutes.

[Elephant snoring] Goncalves: Snoring.

[Chuckles] Narrator: A final shot reverses the effects of the sedative.

They now have just a couple of minutes to get airborne.

[Elephant vocalizes] ♪ To encounter elephants so early in the trip is a hopeful sign that good numbers are surviving in the delta.

In the next few days, Dominique successfully collars 6 elephants from different herds, and straightaway, the collars start to deliver results.

She can see exactly where each elephant and their herd travels... what space they need for socializing, feeding, and avoiding people.

Traveling the delta with their satellite collars, Dominique's elephants are providing crucial, hard data... and are starting to map out the space that she hopes will one day protect all the wildlife of the delta.

Even in such a brief visit, there are tantalizing glimpses of the life the delta could hold.

A great herd, many hundreds of buffalo, an echo of the legendary herds that once roamed here.

And a vision of what this place could be.

Here, where the Zambezi River finally comes to the end of its journey.

Goncalves: The Zambezi River is extremely important, not only in terms of biodiversity and nature, but give us culture, give us, you know, livelihoods, give us many things.

Perhaps without it, it wouldn't be the same.

I think that's the thing that made us all so proud to have the Zambezi, one of the greatest, um, biggest rivers in Africa to just finish here, next to home.

Narrator: From a trickle of water in a far corner of Zambia, this great river has overcome many obstacles on its 1,500-mile journey.

The heat of the African sun.

The rugged geology at the heart of the continent.

The demands of a modern world.

But wherever it flows, it brings life and opportunity.

No more so than here at the end of its journey... as the waters of Africa's great shape-shifting river are finally carried away by the Indian Ocean.

"Rivers of Life", Season 2 is available on Amazon Prime Video ♪ ♪