Original subtitles

Late summer on the Alaskan Peninsula.

Over three million acres of roadless wilderness,

shaped by forces both ancient and living.

These long days of summer mark the start of the

annual salmon run.

18 hours of sun a day help gather the

park's apex predators.

For some, the salmon migration offers a new start.

For brown bears, it means survival.

These are the first fish on the menu since hibernation.

And hunger makes a big catch worth a fight.

There's more than a meal on the line.

An injury might be fatal, but winning could

secure a future.

Because in Katmai, rewards come to those

willing to risk it all.

A few months earlier, long before the salmon

arrived to the coast, the wildlife of Katmai settled

into the relief of spring.

For some, the end of winter means a return to the

meadows of Hallo Bay on the eastern shores of Katmai.

For brown bears, it's an awakening.

She spent the winter hibernating in her den,

where her body was dormant in a phase called torpor.

Incredibly, while in the semi-conscious state,

she gave birth to three cubs and began nursing.

She may be awake, but her body is still

playing catch-up.

It's a kind of walking hibernation.

During these shorter days, her organs slowly regain

their normal function.

And while her heart speeds up and her kidneys and digestive

system come back online, she needs the

grass of Hallo Bay to fuel her and her cubs.

The active months of summer are fast approaching.

And her cubs will need her protection.

Because in Hallo Bay, they aren't alone.

Eager to replenish their winter reserves,

bears travel miles for the rich coastal vegetation

brought on by spring.

But these meadows hint at a deeper story,

one of ancient forces.

Rivers rich with sediment and minerals

flow from the heart of Katmai.

Glaciers, remnants of Katmai's frozen past.

Through the ages, they scour the land,

reshaping and churning the Earth.

Only to retreat and leave behind a far more

ancient sculptor of this land.

Beneath Katmai, two tectonic plates converge.

This collision, part of the Great Pacific Ring of Fire,

awakens giants.

At least 14 active volcanoes are found in Katmai,

more than any other national park in the USA.

Many are echoes from a distant past,

while others are more restless.

Continuing the ebb and flow with glaciers

that shape Katmai.

From the rugged peaks to the meadows of Hallo Bay,

where glacial silt and volcanic ash

make fertile feeding grounds for its brown bears.

But all is not well here.

A battle is unfolding.

Even in play, these young cubs are revealing

their personalities, showing off traits

that will help forge their paths in Katmai.

Strength and bold moves can get you ahead here.

So can keeping your nose out of trouble.

But some mischief is just too much fun.

Though a champion may be unclear,

all of them earn an award.

Together, her three cubs will need

at least a gallon of milk per day.

A big output for a tired mom.

But rest isn't an option.

A male on the hunt for potential mates.

The cubs aren't safe here.

Male bears will kill unrelated cubs

when given the chance.

The family moves on.

Lucky for them, space in Katmai National Park is plentiful.

So long as you can reach it.

Alaska is home to some of the largest tides in the world.

Each day, as the moon counteracts

the Earth's gravitational pull, water drains from the shore...

revealing vast stretches of previously submerged land

and leaving behind bounties for those drawn by the

alluring scent of low tide.

A semi-palmated plover.

Among curious and hungry giants, it never hurts to be cautious...

or fast.

But living among bears can have its perks.

A young male has settled into a mass of seaweed.

A sense of smell seven times that of a bloodhound

makes a desirable scent a major attractant for brown bears.

And this steaming pile is irresistible.

But the plover is searching for something else.

Burrowed deep within the mound, small invertebrates,

normally inaccessible to the plover.

Unless someone digs them up.

This bear might be enjoying a new scent of rotting kelp...

Or soaking in the heat of warm compost.

Either way, he's having way too much fun

to pay mind to the little visitor.

The plover can't afford to linger.

She has responsibilities elsewhere.

Living among more than 2,000 bears in Katmai

demands resourcefulness.

And at times, keeping a low profile.

Especially with what is most precious.

The plover's nest is little more than a scrape in the ground.

Anything more might draw attention.

Their eggs are well adapted to early spring temperatures,

allowing parents to travel farther for food.

Despite their insulating shells, the eggs are at risk from

the cold of spring rains.

She and her mate chose this site carefully,

off the beaten path.

But in Katmai, bears are never far away.

When a threat looms, a plover has only two choices:

Freeze and hope to go unnoticed.

Or flee...

And employ a slightly more dramatic approach.

In the face of danger, semi-palmated plovers

become actors.

Shrieking with the pain of a not-so-broken wing.

Putting on a show meant to distract.

That may or may not have an audience.

Satisfied that she's dealt with the threat,

she can return to her eggs.

She and her mate will watch over the nest for three weeks.

While they wait, Katmai will continue to change.

Spring storms can settle on the coast for weeks.

Long enough to saturate the land.

Driving some to find higher ground.

And even dampen the spirits of playful cubs.

For mom, the rain is not the problem.

The cubs' first year is by far the most demanding.

They depend on her completely.

And she will tend them for at least two years.

During that time, she will not mate.

An unrelated male would prefer she rear his cubs instead.

Which means, if given the chance,

he would remove the cubs she is raising.

His size gives him the advantage in a fight.

Even so, confronting her would still be a battle.

For her, the stakes are even higher.

The meadows that promised so much are now a trap.

For the sake of her cubs, it's time to leave.

But traveling miles to another meadow

would require too much energy.

And Hallo Bay isn't the only place

with the threat of boars.

She seeks refuge elsewhere.

The Alutiiq people call it Ninagiak,

the place where the weather clears.

Few boars venture away from the mainland to reach this island,

making it a paradise for young bears

and an ideal spot to take the cubs.

There's only one problem.

A two-mile stretch of ocean is a dangerous swim for young cubs.

But Mom knows their luck could change.

It'll just take patience.

Others are set to leave Hallo Bay as well.

A wandering gray wolf with a nearly white coat

common to the far north.

His pack's calls echo across the bay.

Wolves may leave their families in search of new prospects.

In winter, they pursue game in the lowlands.

But Katmai's summer brings the best hunting opportunities.

And at this time of year, every corner of the park

fills with life and death.

Katmai is one of the few places in the world

where wolves hunt the coastline.

For nearly 500 miles, the shores of Katmai

meet the productive, nutrient-filled waters

of the Pacific Ocean.

For wolves, it is a vast hunting ground

where seals and sea otters may be caught off guard.

This wolf is drawn north.

Out of the shadow of volcanoes and glaciers,

to the outflow of one of the park's longest rivers.

And a gathering place for one of the largest

migrations on Earth.

But grand events can have humble beginnings.

The juvenile salmon, Parr.

These salmon spend their first years

adapting to a saltwater life, slowly moving toward

coastal waters.

Their bodies are streamlining and changing color.

A process called smoltification, preparation for the challenges

of an ocean environment.

Until then, life is good.

The insect hatches of early summer are a welcome feast.

Undergoing such dramatic changes requires vast amounts of energy.

Even more vital is what the salmon are learning.

The "smell" of their natal waters.

The par imprint on a chemical signature

and magnetic profile unique to this exact area.

For the salmon who moved to the ocean years earlier,

the memory is a guiding beacon.

It's a homecoming the wolf has been waiting for.

After years in distant waters, the salmon use summer

light to gather in bays and begin their final journey.

Where they are met by Katmai's giants.

For months, their diet has been scarce,

lacking the fats and proteins needed for hibernation.

These salmon are a lifeline.

Katmai's population of brown bears

is unrivaled among the national parks.

This abundance depends almost entirely

on the yearly return of salmon.

It's a cycle that drives an ecosystem,

a heartbeat of life and nutrients.

The salmon follow their magnetic compass

to the mouth of their natal stream.

But they're slightly off course and drifting into

dangerous shallows.

These are only the first of millions of fish

that will make their way into Katmai's

nearly 6,000 miles of rivers and streams.

One of them has built a reputation

distinct from the rest.

Brooks Falls.

At six feet tall, it's a towering gauntlet for salmon.

And home to some of the world's most famous hungry giants.

Viewing platforms offer a candid glimpse

into the lives of brown bears.

The accessibility and drama of Brooks Falls

makes it by far the park's most popular attraction.

Leading the beaten path means being slightly

more enterprising.

Katmai is a true wilderness.

Nearly 4 million acres of rugged terrain.

The nearest large city is hundreds of miles to the east.

One of the only ways to explore such a vast and remote place

is by taking to the air.

Few know and bear witness to Katmai's interior

of glaciers and volcanoes as well as bush pilots.

While most people come to Katmai's for its bears,

the motivation for the park's creation lies here.

In what seems a barren wasteland.

Billions of tons of volcanic ash and pumice.

In some places, more than 500 feet deep.

This valley is the site of the largest volcanic eruption

of the 20th century.

But there was no one here to see it.

When the earth began shaking in June of 1912,

the last of Katmai's fishermen and their families

heeded the warning, moving far from the

mountains they felt stirring.

On June 6th, Katmai's newest volcano was born.

A cataclysmic eruption that cooled the planet

and dropped debris as far away as the Mediterranean.

When the veil of ash fell, Mount Katmai's was transformed,

and the eyes of the scientific world

were drawn to Alaska.

None were more determined than Robert F. Griggs.

Commissioned by the National Geographic Society,

he led a team of explorers,

scientists, and photographers into a turbulent land

ravaged by fire and floods to the slopes of Mount Katmai.

Standing above the smoking crater,

he was astounded and out of his element.

Untrained in geology, Griggs believed he was looking

at the source of the cataclysmic eruption.

But he was wrong.

Six miles away from Katmai Crater

stood the evidence of Griggs' error.

A lava dome at the center of the vast valley.

Novarupta.

Griggs and his team dismissed the steaming cone,

unaware of its true power.

But what they had stumbled on was the real source

of the 1912 eruption.

An explosion so big that it collapsed the

gigantic volcano nearby and unleashed a volume of ash

30 times that of Mount St. Helens,

creating a pyroclastic landscape

strewn with pumice boulders and hissing fumaroles.

Enamored by the alien landscape, the team settled into

the valley to explore and found themselves caught

between scientific duty and childlike wonder.

Captivated by his findings, Griggs led a total of

four expeditions here and deemed it the Valley

of Ten Thousand Smokes.

Griggs believed the valley to be a new Yellowstone,

that the volcano had birthed the beginnings

of geyser fields and hot springs,

destined to draw as much tourism as any of America's

greatest national parks.

President Wilson agreed.

In 1918, Katmai's was set aside for future generations to enjoy.

In the decades that followed, lava cooled and

steam diminished.

The Valley of Ten Thousand Smokes grew quiet,

and the focal point of Katmai's shifted from the valley

to its wildlife.

After three weeks of safeguarding their eggs,

the big day has finally come.

Pushing through the shell takes some time,

but like most ground-nesting birds,

plovers are born far more developed

than their tree-bound cousins and are expected to

run before they walk.

From day one, plovers are outfitted

with the tools needed to survive here.

Warm, camouflaged feathers, strong legs,

and a sense of adventure.

As days begin to shorten in late summer,

the Hallo bay family is still unable to reach their goal.

The average daily tides aren't low enough

to open a way to Ninagiak Island,

and swimming isn't an option for the young cubs.

But today's tides are different.

On rare occasions, the moon makes the closest

pass of its orbit while full, aligning its gravitational

pull with that of the sun.

A King Tide.

Opening a land bridge to the island

for a few precious hours.

Enough time for the mom and her three cubs

to make the two-mile crossing.

And finally, as the land bridge begins to close...

...they find refuge on Ninagiak Island.

Miles up the coast, and king tides coincide with

Katmai's biggest showdown.

The wolf has waited patiently for the time to be right.

As the salmon push into fresh water,

he has to be selective with his hunting grounds.

As the land flattens and the river spreads out,

the salmon are forced from the comfort of the depths.

A perfect place to stage an ambush.

Without the grasping claws and articulating

arms of a brown bear, the wolf must be more precise.

Catching the salmon at just the right moment

as they cross the shallow gravel beds.

Easier said than done with nothing but your teeth.

A single salmon can provide a whopping 4,000 calories.

Even so, life is feast or famine for a wolf.

He'll eat up to 20 pounds of fish when given the chance.

But his catch hasn't gone unnoticed.

Many times the wolf's size,

the loitering male makes for an intimidating audience.

So much for this fishing spot.

The oversized neighbor isn't going anywhere soon.

Katmai's ruling class of bears makes flexibility a necessity.

The wolf has to find overlooked opportunities.

The first wave of salmon has pushed upriver.

But the run lasts for weeks.

And even the smallest streams attract migrating fish.

This tiny trickle of water won't bring in enough salmon

to feed a brown bear, but it might be perfect

for a lone wolf.

For salmon on the move, the boundary of

Katmai National Park protects their natural highways.

There are no dams.

And no roads leading into the park.

With such pristine waterways, Katmai is home to the

largest salmon run of any national park.

And for them, this is a one-way journey.

As the salmon push upriver, their bodies

irreversibly transform.

Dorsal humps and bands of color signal a male's virility.

Their teeth elongate, weaponizing for battles ahead.

Females divert energy from vital organs

toward egg production.

And flanking their path, bears entering hyperphagia,

an insatiable period of hunger in the months

before hibernation.

Even apex predators miss more than they catch.

Brute strength and speed have their place.

But clever hunters use Katmai's terrain

to their advantage.

These cascades attract a family interested in working smarter,

not harder.

Shallow rapids and uneven boulders

leave salmon nowhere to hide.

Only those with enough strength, stamina,

and luck survive to forge ahead

to spawning grounds where new battles await.

These calm, oxygenated waters are the nursery and graveyard

for countless generations of salmon.

Here, females excavate hollows in their natal gravel beds,

a small hope of safety in otherwise dangerous waters.

As females dig, aggressive males

secure position.

Each strives to be the one to fertilize her eggs

before time runs out.

A growing family can eat dozens of salmon each day,

and keeping ahead of teenage appetites

is no mean feat.

Leading any successful family is a skilled and

tireless mother.

Those beneath the surface fight just as hard.

When given the chance, bears target females

carrying eggs.

Relishing the highly nutritious roe,

any spillover is spotted by sharp-eyed gulls.

And the frenzy is only beginning.

At the peak of the spawn, the river boils with

struggling salmon, bringing easy hunting for some

and fierce competition for others.

The strongest live to pass on their genes,

but victory takes its toll.

The remaining salmon are shadows of their former selves.

Spawned out, they become living corpses.

Their bodies deteriorate.

Their last remaining nutrients return to the land.

This rebirth is a signature of Katmai National Park,

a landscape made of transformations,

both big and dramatic and small and personal.

Here, bold first steps lead to grand migrations,

The residents of Katmai continuously benefit

from the ebb and flow of new beginnings.

In a land that provides something for everyone,

a satisfied lone wolf can rest and enjoy.

And a family can find the space it needs to thrive.

The tides that brought them to Ninagiak

keep them fed with shellfish and kelp.

They'll return to the mainland when they've grown strong,

and the tide is right.

As the air once again turns brittle,

the national park shows its full range of colors.

Katmai has offered so much opportunity

that its brown bears are full and healthy.

All of the food they've been able to store

will carry them safely through the dark months ahead.

For others, the cycle of life is now complete.

In less chaotic water, the salmon still feed anyone

willing to take a dive.

As winter draws near and the days lose their light,

Katmai National Park continues to foster life

on a scale as grand as the park itself.