Original subtitles

NARRATOR: 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...

..and the magical, hidden worlds of the Danube.

Great rivers are the lifeblood of planet Earth.

At the top of North America is a legendary river...

..flowing through some of the wildest country on Earth.

Relentless.

Immense.

For the First Nation people, it's seen as the Great River.

The Giver Of Life.

Its natural riches have long sustained all those

that live along its banks.

It gathers its waters...

..from vast ice fields...

..and great lakes...

..from mountain streams...

..and tundra plains...

..and brings life wherever it touches.

It seems all-powerful, but another force is at work here.

The cold of the Arctic winter.

When it strikes, this river is transformed.

It becomes a river of ice.

A frozen highway, upon which many will depend,

during the long, dark winter.

From icebound lifeline...

..to free-flowing giant.

This is the Yukon.

North America's great frozen river.

For 3,200 kilometres, the Yukon flows in a great arc

through northwest Canada and central Alaska to the Pacific Ocean.

Along the way, it gathers water from 800 square kilometres of wilderness,

an area four times larger than Great Britain.

But its story begins deep in the coastal mountain ranges

of British Columbia.

The Juneau Icefield,

3,800 square kilometres and over a kilometre deep.

The flood of summer meltwater from these glaciers

fuels the Yukon on its journey to the sea.

But this far north, the seasons change quickly.

As autumn temperatures plummet below zero,

the Yukon's tap turns off.

Soon, the entire river is hidden beneath a shield of ice.

Despite the October chill,

one of the Yukon's remote tributaries remains ice-free.

In Fishing Branch River,

thermal springs percolate from deep underground,

warming the stream just enough to keep it flowing.

It creates an opportunity for some of the Yukon's toughest characters.

For weeks,

chum salmon have been battling their way upstream from the Pacific.

Racing the freeze, they have swum over 2,400 kilometres,

following a long-remembered scent to reach their spawning beds.

On arrival, the females excavate shallow scrapes,

or redds, in the gravel.

Around them, the hook-jawed males tussle for prime position.

They need to be close to fertilise the thousands of eggs

the females release into their nests.

But spending so much time in the shallows leaves them vulnerable.

Up to 40 grizzly bears visit the creek

during the brief spawning season.

With air temperatures at 30 below,

wet fur quickly freezes, coating the bears in frost.

These are the Yukon's ice bears.

Unique, because the late salmon run means they can still hunt

when other grizzlies are already hibernating.

These cubs may lack the pioneering spirit.

Their mother certainly does not.

She keeps the first catch of the day for herself.

Her cubs are hungry

and determined not to miss out on breakfast.

They just need to find a way across the river.

Too slow.

Mum's straight back in the stream...

..chasing a second breakfast.

When her direct attack doesn't work, she gently paws the water,

encouraging the salmon into the shallows

where they can be picked off.

If the fishing is good, she will eat 30 kilos every day...

..feasting on the juiciest, energy-rich parts,

like eggs and skin.

But as the salmon run dwindles,

even old fish heads start to look appetising.

The bears need to put on enough weight

to see them through the long winter.

After a hard day's fishing, a good scratch helps them defrost.

Once the fish are gone,

even these tough ice bears will retire to their dens

to bed down for hibernation.

As the northern hemisphere faces away from the sun,

an intense cold now settles along the Yukon.

Across northern Canada and Alaska,

the Yukon is locked away beneath several metres of ice.

It will stay frozen for six months or more.

Temperatures tumble to -50.

As winter blizzards sweep along the Yukon Valley...

..the hard river ice is blanketed by snow.

In a land with few roads,

the frozen river becomes a highway through the forest.

DOGS BARK AND HOWL

And the skills needed to run these ice roads

still flourish along the Yukon.

KYLA BOIVIN: I've been travelling on the river my whole life.

NARRATOR: Kyla Boivin is a dog-sled racer

and the frozen Yukon is her racetrack.

KYLA BOIVIN: I like how it all changes from mile to mile.

The land is so big.

It's the highway of the north, right?

NARRATOR: She's putting her top team through their paces

along a section of the Yukon Quest challenge...

..a sled race billed "The Toughest on Earth".

It's a 1,600 kilometre test of endurance and teamwork,

run between Whitehorse in Canada and Fairbanks in Alaska.

Kyla has tackled this marathon seven times...

..the first when she was 18-years-old.

But now she rides just for the thrill of it.

The race harks back to a time when the frozen Yukon

was the only link between isolated settlements and the outside world.

KYLA BOIVIN: Temperatures can be 50 below.

You can have a blizzard where it drops eight inches of snow

and the trail is gone.

There are spots that are just windswept

and it's barren and it's like the moon down there.

NARRATOR: Kyla is following the same call of the wild

that drew the early pioneers to the Yukon.

KYLA BOIVIN: You're only going to have six hours of daylight in the winter, right?

In the deepest winter.

And when it's dark you only see your head lamp beam.

That's not very far to spot trouble.

You are completely relying on the dogs

and they are completely relying on you.

And they're such wonderful creatures.

They're my favourite creatures on this planet, the sled dogs.

Definitely.

NARRATOR: Even today, life for a musher and dog team out on the ice

is much the same as in those pioneering days.

DOG BARKS

Some straw for the dogs and a fire to melt snow for coffee

can make life a little more comfortable.

It's bitter, 25 below.

Ooph.

They're good dogs.

Once they see the straw, usually, these guys have camped a lot,

so they know straw means we're staying awhile.

NARRATOR: Despite the cold,

the frozen river is a lifeline through these northern forests.

Even in deep midwinter, lynx are on the prowl.

Using the windswept ice river

means they can avoid deep, energy-sapping drifts.

Their huge furry paws act as snowshoes...

..helping them move effortlessly across soft snow.

Lynx are top predators...

..but a half-ton moose is way out of their league.

They have something much smaller in their sights.

Snowshoe hares can make up to 90% of their winter diet.

But being a specialist hunter brings its own problems.

Hare numbers rise and fall dramatically

in regular 10-year cycles.

In years with few hares, many lynx starve.

Even in good years,

pursuing such elusive prey means covering many kilometres every day.

As they wander these well-travelled highways,

lynx mark out their territories...

..with a squirt here...

..and a squirt there...

..leaving scent to help stake their claim to a stretch of frozen river

and to advertise for a mate.

These chemical signposts are the only way these loners

can keep in touch in such remote country.

And this really is North America's wild frontier.

Along the Yukon, there are no big cities and few roads.

Only four bridges span its 3,200-kilometre course.

Just 125,000 people live in the entire Yukon Basin.

Close to the Alaska-Canada border, 650 kilometres east of Anchorage,

is one of the few riverside towns - Dawson City...

..where the Yukon is joined by its most famous tributary...

..the Klondike River.

Dawson sprang up almost overnight

after gold was discovered here in 1896.

By the following year,

gold fever had lured 30,000 fortune hunters

to this remote river bank.

A lucky few struck it rich.

Most left empty-handed,

defeated by the Yukon's crushing hardships.

In just a few years, the gold petered out

and the rush was over almost as quickly as it started.

But Dawson lived on,

a beacon of light in a sea of wilderness.

One of the strangest reminders of those wild times

can be found in the Downtown Hotel saloon,

where the preserved frostbitten toe of a Yukon prospector

has become the key ingredient in a unique cocktail.

Taking the Sourtoe challenge has become a rite of passage

for anyone who visits Dawson today.

And if you dare, we can serve the toe.

Are you ready?

I guess so.

MAN: You'd better be, cos here we go.

You can drink it fast, you can drink it slow,

but your lips must touch this gnarly toe.

Just your lips.

No teeth, no tongue, no tonsils.

Slainte.

Should I just do it? — Oh.

MAN: You got it.

WOMEN GROAN

MAN: That was well done.

That was well done.

Perfect.

THEY LAUGH

NARRATOR: Just when it seems the cold

will never release its grip on the Yukon...

..there's a sign in the heavens that change is coming.

The Aurora Borealis.

The Northern Lights.

These atmospheric light shows often reach their peak

just as the Earth's orbit

swings the northern hemisphere back towards the sun.

It marks a moment of transformation,

as new energy pulses along the Yukon.

Rising temperatures and the stirrings of long-dormant currents

open the first breaches in the frozen river's defences...

..just in time to greet thousands of noisy migrants to the Yukon.

Trumpeter swans have flown over 1,600 kilometres from southern Canada,

en route to their breeding grounds further north.

Marsh Lake gives these huge birds a chance to rest and refuel,

but only if their timing is spot on.

If they arrive before the thaw,

ice stops them feeding on the sedges that grow on the lakebed.

Arrive too late,

and spring floods put these plants beyond reach.

They've got it just about right,

although the cold April nights still glaze over the open water,

so the early risers must help break the ice.

Even for these long-necked birds,

it's a stretch to gather the vegetation a metre down.

Unable to reach the plants for themselves,

smaller migrants like wigeon stick close to the swans,

scooping up any leftovers.

After a short stay, it's time to move on,

chasing the spring thaw as it moves north.

The Yukon gathers its waters from across a vast backcountry...

..and it may take many more weeks

before the thaw reaches its Arctic tributaries.

Even in May, these are still frozen solid.

Rivers like the Porcupine.

800 kilometres long, its course takes it north across the Arctic Circle,

then back south to join the Yukon.

At its most northern point

is the First Nation Vuntut Gwitchin village of Old Crow.

Here, life revolves around subsistence fishing and hunting.

PAUL JOSIE: Winter in Old Crow can be harsh, it can be cold.

Being above the Arctic Circle,

we experience earlier winters and later springs.

The Porcupine River is the last,

one of the last large rivers to break up

and that's where we're at right now.

NARRATOR: Every day, Paul Josie climbs the bluffs above the village

to scan the frozen river, watching and waiting.

PAUL JOSIE: As I stand and witness the changes in front of me from the river

and you hear the geese in the sky,

and the water trickling down the mountain

and you can feel the warm air on your face,

it gives me a sense that spring will be upon us.

NARRATOR: There's one sign above all that means spring is close.

The arrival of the Porcupine caribou herd.

Over 200,000 animals on the move.

A 2,500-kilometre migration,

the longest by any land mammal on the planet...

..taking them to their calving grounds on Alaska's Arctic coast.

Early arrivals at the still-frozen Porcupine River,

mainly pregnant cows, walk across the ice.

But temperatures are rising rapidly.

Melting ice eases away from the banks

and starts to break up.

As more caribou arrive...

..they face a dangerous, shifting patchwork of unstable ice

and open water.

There's no way through.

They are forced to wait as a growing mass of ice

surges downstream towards Old Crow.

Slabs of ice jam against one another, blocking the river.

Some caribou get caught out,

marooned as the ice breaks up around them.

The lucky ones are carried back to shore,

kilometres further downstream.

Ice continues to build around Old Crow

until the pressure can no longer be contained.

Kilometres of river ice stream past,

heading for the Yukon.

PAUL JOSIE: Ever since I was young, the break-up of the river

has always been an exciting time for my community.

Watching the break-up is literally watching winter wash away.

NARRATOR: The remaining caribou now take their chances with the ice.

PAUL JOSIE: Watching the Porcupine caribou swim across the river,

navigating through ice chunks...

..you get a sense of worry for this animal,

as you want them to succeed, you want them to cross

and you want them to be safe.

As the ice moves off downstream,

the stragglers make their way across the river...

..playing catch-up with the rest of the herd.

Winter is finally letting go.

Now that the river has broken up, um...

it's actually just waiting for more ice to clear,

waiting for it to be a little safer to travel.

And then I can put my boat in

and start travelling on our highway again.

NARRATOR: After months of isolation,

the inhabitants of Old Crow can now reconnect with the Yukon.

As the great frozen river turns its back on the Arctic,

it starts to come alive.

Now bathed in near-continuous summer daylight,

temperatures continue to rise.

The snow and ice that brought the Yukon to a winter standstill

Now re-energises the river.

With every stream and tributary adding its own pulse of meltwater,

the Yukon's power steadily grows.

With the flood comes something just as important as the water.

An ever-growing cargo of rock dust from distant glaciers...

..and mud from eroded valleys.

This meltwater flood

turns the Yukon into a formidable and relentless mud-filled giant.

Over the short summer,

the river will shift more than 70 million tonnes of sediment.

Most of it carried all the way to the ocean.

This unique mineral signature

now helps guide waves of salmon back to the Yukon.

Runs of chum, coho, pink and king salmon

battle their way thousands of kilometres upstream

to spawn in the river's headwaters.

For thousands of years,

the indigenous First Nation peoples harvested the fish.

A summer bounty that fed them through the winter.

It's still a tradition for families

to head to remote riverside fish camps to catch and prepare salmon.

Sisters Faith Peters and Kathleen Peters-Zuray

from the Athabaskan First Nation

are heading to their camp at Rampart Rapids.

FAITH PETERS: I'm middle of the river clan

and we've been surviving on king salmon all our life.

We've been coming to fish camp here for, like, 35 years.

NARRATOR: Over those years,

the sisters have witnessed dramatic changes along the river.

Recently, the Yukon's many salmon runs have gone into steep decline...

..victims of a shifting climate and over-fishing in the Pacific.

Strict limits are now placed on catches

and if numbers of returning salmon are very low,

no fishing is allowed.

The family wait for this summer's decision,

relayed via the local Mukluk radio station.

RADIO: The pre-season projection does not meet the threshold

of 300,000 fish needed to allow subsistence fishing.

Therefore, subsistence salmon fishing will be closed

to begin the fall season.

Subsistence fishermen should prepare for continued closures.

NARRATOR: Despite this bad news, the sisters are determined

to keep up the traditional knife skills they learnt as children.

KATHLEEN PETERS-ZURAY: It's hard for us to not to come to fish camp and to cut fish,

cos this is what we've been doing all our life.

NARRATOR: With no fresh fish to cut,

Kathleen retrieves what's left of last year's catch

from the camp freezer.

Ooh, there you go.

We're ready.

This is one of salmon that was in the freezer from last year,

so it's a little soft, but it's still beautiful.

FAITH PETERS: It's not even a job for us to do this. It's a happy vacation.

NARRATOR: The strips are hung in the breeze to dry.

It's amazing that we're using frozen fish...

..and it's turning out pretty good.

It's going to taste like gold.

After a day in the sun,

the oil-rich strips are moved into the smokehouse.

The smoke helps preserve the fish

by creating a coating that slows decomposition.

In past years,

this smokehouse would be full to the rafters with salmon.

These few strips are a sad reminder of how bad things have become.

KATHLEEN PETERS-ZURAY: So there was no summer chum, no king and no fall chum.

That is...

..unprecedented.

We've never seen that.

It makes me sad. It really makes me sad, cos...

..for us to have a dinner without king salmon,

it's almost like starving.

KATHLEEN PETERS-ZURAY: It hasn't really hit me, really,

but we're losing a part of our culture.

It's...

It's devastating.

NARRATOR: The sisters can only hope

next summer brings more salmon back to the Yukon,

so they can fill the smokehouse once again.

By September, autumn is colouring the Yukon's banks.

Bull moose are putting the finishing touches to something remarkable.

Every year, they grow a new set of antlers.

In older bulls, these can be two metres across and weigh 25 kilos.

Bulls need top-quality grazing to grow these huge racks

and lots of it.

Over 15 kilos every day.

Up to half their summer diet consists of water plants,

rich in protein and vital bone-growing minerals.

At their peak, the antlers are growing at two centimetres a day,

making them the fastest-growing organ in the animal kingdom.

All this effort is for just one thing - to get noticed.

And this bull's eye-catching headgear has already done its job.

All he needs to do now is dig a pit and soak the soil with his scent,

releasing pheromones that add to his already impressive allure.

He's irresistible.

Now over a kilometre wide and still over 1,000 kilometres from the sea,

the mud-filled Yukon swings southwards...

..into some of the wildest country in Alaska.

With no roads or rail links,

the few isolated villages here rely on the Yukon

to stay connected to the wider world.

Bush pilots can make some deliveries...

..while anything bulky must be carried by barge.

CAPTAIN LESTER HAKEY: This is the last run of the season.

We do about between 13, maybe even 14,000 miles,

river miles, transporting cargo for customers.

NARRATOR: Captain Lester Hakey has worked the Yukon for 26 years

and knows this autumn voyage is risky.

Most of the challenges are the river depth.

That's the biggest challenge.

It's only September, but the headwater streams

that feed the Yukon are already starting to freeze,

slowing the flow of water into the main channel

and river levels are dropping.

LESTER: You got big river, you got wide river.

But you still have channels

where the river will go from 35 feet to six, seven, eight feet, you know,

and then you can get yourself stuck down there.

NARRATOR: The currents are incredibly powerful...

..making navigation tricky

through constantly shifting bars and mud banks.

And the barge doesn't stop just because the sun goes down.

They are on a tight schedule.

Lester shares the piloting with Sean Wright.

It's six hours on, six off, around the clock, seven days a week.

There's really nothing that we won't move.

If it's got wheels or if it can be picked up by heavy machinery,

we will haul just about anything that you can bring us.

We've got excavators, loaders,

we've got 70-foot long conveyor-belts on trailers.

LESTER ON RADIO: Yeah. Keep on rolling, Sean. Looking good.

NARRATOR: And with no docks or piers in the village,

deliveries are unloaded down make-shift ramps.

SEAN WRIGHT: We've got people's personal vehicles.

Thanks a lot. All right, dude.

Alll dois get it from point A to point B, man.

Oh, yeah. - Yeah. Here you go.

BOAT HORN TOOTS

People's food, groceries, soda cans.

Building materials.

Yeah, just about anything you can think of.

NARRATOR: If anything has been forgotten,

it's eight months before the spring thaw allows deliveries again.

The barge's most precious autumn cargo

is 700,000 litres of fuel.

It's what villagers rely on to warm their homes

and run their vehicles once winter comes.

LESTER: I love the challenge.

I love the challenge of the whole thing. It's just...

It's awesome because when you get done, and you're, you know,

you think you've been beat,

and then all of a sudden you get it done, and everybody's happy

and you got the freight off to the people and they're happy...

..you feel a sense of accomplishment, you know? Yeah.

That's part of the reason why I love this, you know. I mean,

you can't beat this office to work in, can you?

I mean, really.

NARRATOR: After the last delivery, it's an eight-day battle back upstream

to their winter quarters before the river freezes.

Meanwhile, the Yukon, now at its widest, and most remote,

forges westward into a very different world.

With the mountains far behind,

there's now almost no gradient left to drive the river forwards.

Across this flat, exposed landscape, the Yukon slows and spreads,

splitting into a tortuous network of meandering channels.

Breaking up this maze of waterways is an endless boggy tundra...

..pockmarked with thousands of ponds.

This is the Yukon Delta...

..covering over 130,000 square kilometres, larger than England,

and one of the largest deltas on the planet.

At the very end of its journey, the Yukon has one final surprise.

Rising out of the waters surrounding the southern delta is Nelson Island.

Here, at the very edge of the continent,

live some remarkable creatures.

Musk ox.

With their fine woolly coats, these relics of the last Ice Age

can shrug off the very worst delta weather.

Days are spent gathered in small family groups.

A tight-knit sisterhood of cows with their calves

and one very large bull.

He's trying his best to corral the wandering females...

..constantly checking if any are ready to mate.

It's the rutting season

and his harem has caught the eye of a young bull,

who fancies his chances.

As the herd drifts over the hills...

..the hopeful youngster follows, slowly getting closer.

Finally, his presence forces the resident bull to react.

This is all about intimidation...

..as rivals assess each other's size and strength.

A few tentative shoves

and this youngster quickly realises he's more than met his match.

During the rut,

contests like this are kicking off all over the tundra.

If rivals are evenly matched,

things can escalate into full-blooded confrontation.

Thick skulls and ten-centimetre horn bosses act like helmets

protecting them from these earth-shaking collisions.

Intruder seen off.

The victor has won the chance to father next year's calves.

But now, across this wilderness,

all musk ox turn to face the greatest challenge of the year.

After the freedom gained during the intense summer...

..the Yukon must once more yield to the power of an Arctic winter.

The first snows already blanket the high country.

Cold is silently creeping back along the valleys.

This year's salmon runs may have been poor...

..but some fish have made it back to their spawning streams.

As life along the Yukon turns full circle...

..this is where their journey will ultimately end.

Their deaths will help others to survive the winter.

And this is not the end of their story.

Nurtured by the Yukon's waters, salmon eggs pulse with life.

For the salmon...

..and all those living in this wild country,

the river holds the key to the future.

The Yukon will always be the natural and spiritual heart

of this great wilderness.

North America's legendary frozen river.

For the Earth's Great Rivers team,

the challenge of filming in the Yukon

was in finding ways to access one of the most remote regions on Earth.

A mission that took them on many intrepid adventures.

But it all started with an old school bus.

Once an ordinary school bus,

now it's on the ultimate field trip for the BBC.

LOUISA GILBERT: So our small crew is completely self-sufficient

when we're out in this bus.

As well as making all the power from the solar,

we are kitted out with VHF radio, satellite phones.

We also have a cell booster,

which will help amplify any cell service that might be in the area.

I think if I just park in here.

NARRATOR: Travelling with everything they need,

the crew head into the river's far-flung headwaters region.

They have set themselves the challenge of capturing

a series of dynamic shots of creeks throughout the year,

with the camera moving fast,

just a few centimetres above the water's surface.

Camera operator Ollie is adapting a First Person View Drone,

or FPV, for the task.

OLLIE: These are the FPV drones.

These allow us to see

from the perspective of the drone

as we're flying, which allows us

to get much tighter shots,

go through smaller gaps,

which we just wouldn't be able to do safely with these bigger drones.

Not only does the drone need to be waterproof,

but we need to be able to retrieve it and it not sink if it does crash,

so we've got these quite high-tech pool floats

with ping-pong balls in them.

So I'm just going to test them out.

Success. It floats.

NARRATOR: Having survived the bathtub test, it's time to try it for real.

LOUISA: Let's give this a go.

NARRATOR: Using a headset, Ollie can see from the perspective of the drone.

NARRATOR: It's a process of trial and error,

which the crew will perfect through their time filming.

And different creeks present different challenges,

both for flying and for retrieving the drone.

OLLIE: Fingers crossed. What could go wrong?

OLLIE:

NARRATOR: As winter draws in,

the task becomes increasingly difficult

and drone recovery becomes even more nerve-racking.

OLLIE:

NARRATOR: Despite the mishaps, Ollie's drone has worked,

delivering a completely new perspective.

Dramatic low-level shots along some of the wildest

and most inaccessible parts of the Yukon.

To capture the final chapter of the Yukon's story,

the crew have to leave the bus behind

and embark on their most challenging journey of all...

to film musk ox herds that roam a remote island

where the Yukon empties into the Bering Sea.

Standing in their way is the Yukon's vast roadless delta.

The only way across is by plane.

Waiting for them in the remote village of Toksook Bay

is local Yupik guide Jackie Cleveland,

who has organised some unusual accommodation

in this rarely-visited community.

JACKIE: It's very remote here. There are no hotels.

So this is the Nelson Island School, where we will be sleeping.

NARRATOR: Jackie introduces the class to the crew.

JACKIE SPEAKS OWN LANGUAGE

THEY CHATTER

JACKIE: So here is the library,

which we've turned into a sleeping space slash office.

This is one bedroom. Cosy.

And then another bedroom is down here.

Neat.

NARRATOR: With their base camp set up,

the team set off on the next leg of their wild journey...

..this time taking to all-terrain vehicles.

The best way to navigate the island is to follow the coastline.

The flat beaches make for faster going

than the dense tundra that cloaks the interior of the island.

But this route has its own challenges.

LOUISA: We're in a bit of a race against the tides.

We have an hour to get there and if we don't make it back,

we're stuck there.

So time's on. Pressure's on.

With the tide coming up, the crew's travel corridor is shrinking.

And they still haven't seen any musk ox.

With the way ahead disappearing fast,

they have no option but to head inland.

Up here, it can take an hour to cover just a couple of kilometres.

After hours of bumpy travel,

the team reach areas where even the ATVs struggle.

The only option is to send a drone up

to help scope out the endless rolling hills.

They spot a herd, sheltering in one of the island's hidden valleys.

Thanks to the drone, the crew can at last start filming.

Spending time with these magnificent animals

makes a fitting end to a journey that has taken the crew

to the wildest parts of one of the wildest rivers on Earth.