South Korea: Earth's Hidden Wilderness

Korea.

An ancient mountain kingdom.

A land divided by conflict.

But in the natural world, there is another side to Korea.

In the south are pockets of untouched wilderness.

Rich habitats...

..with extraordinary creatures...

..and spectacular natural events.

HE SHOUTS

A place where nature and mankind have lived in harmony for centuries.

This is Korea.

Korea lies on the eastern edge of Asia.

The peninsula is 700 miles long and 150 miles across...

..and is split into two nations.

But long before modern conflict divided the land...

..tectonic plates collided to create a dramatic landscape.

60 million years ago,

unimaginable forces raised the jagged peaks that dominate

the east of Korea.

In the central region are lush, temperate forests.

Further south, these give way to fertile wetlands.

And where the land finally meets the sea,

the shallow incline creates vast tidal ranges...

..with endless mudflats...

..teeming with life.

Korea is surrounded on three sides by ocean.

It has over 5,000 miles of coastline.

In the far south, the islands of Jeju

are home to a resident population

of Indo-Pacific bottlenosed dolphins.

Dolphins are often wide-ranging...

..travelling from place to place in search of food.

But this group chooses to live here all year round,

in the bountiful waters

around these volcanic islands.

Bottlenose dolphins are highly social creatures...

..and live in tight-knit matriarchal pods.

Group members communicate constantly.

Each dolphin is identified by its own signature whistle.

And they are quick to recognise

the presence of any strangers in their territory.

Today their curiosity is piqued by a presence here that is almost

as ancient as their own.

Dolphins can be wary of divers, but not of this one.

Like them, she dives free,

exploring the depths on a single breath.

The pods have grown up sharing these waters

with an all-female free diving community...

..known as the Haenyeo,

sea women.

She scours the sea bed in search of its natural treasures.

They live in harmony,

as they have done for hundreds of years.

Soon the season will change,

and these waters will be filled with prizes for the Haenyeo.

300 miles north, on the Korean mainland...

..the palaces of the Joseon kings...

..an imposing legacy of the powerful dynasty

that once ruled here.

But the palaces are now home to a family of a different kind.

A family of raccoon dogs.

Though they are named for their resemblance,

they are much more closely related to dogs than they are raccoons.

This opportunistic family have left their usual forest dwelling

for the safety of the palace grounds.

For the most part, life is good here.

But they're not the only ones to take advantage

of the opportunities here.

There is a rival group that occupies

the other side of the palace grounds.

With young pups, the family's father must be extra vigilant.

At around four months old, pups learn to forage for themselves.

But hunting insects requires a little practice.

Raccoon dogs will eat almost anything.

Tonight the family is anticipating

something extra-special on the menu...

..cicada nymphs.

A lavish banquet of juicy beetles.

The nymphs emerge en masse during a narrow window in the summer.

For one night only, the family will have more food than they can eat.

The nymphs have spent five years slowly growing in the soil.

They must now find higher ground...

..where they can metamorphosise into their flying form.

Such rich rewards attract hungry rivals.

A pack of young males from the far side of the palace grounds are also

eager to have their fill.

Distracted by the feast,

the usually wary father has strayed into harm's way.

He is outnumbered, and in danger.

The mother and pups retreat to a safe distance.

Their father escapes,

injured, but lucky to be alive.

His mate tends to his wounds.

The palace may provide rich feeding grounds

but such wealth comes at a price.

Some of the cicadas have reached their destination.

After years of lying underground, the lucky ones will get their wings.

During metamorphosis, they are at their most vulnerable.

But up here, at least they are safe from the hungry pups.

Now they will devote the last chapter of their life,

just one month,

to finding a mate.

It is a cycle that has played out here for hundreds of years.

During this time, the world beyond these walls has changed.

The palace is now surrounded by South Korea's capital city,

Seoul.

Seoul is home to one of the most densely packed human populations

on the planet.

It is easy to see why the raccoon dogs seek refuge in the palace.

But there are places where humans and nature coexist

in perfect harmony.

The island of Marado...

..the southernmost point of Korea.

Beyond the cliffs and caves, there is a small community,

the Haenyeo, sea women, as they are known here.

Today they are preparing for an important dive.

There are men on the island too,

but a sisterhood drives the local economy.

Most divers are over the age of 60...

..and some are much older.

At this time of the year

the waters here provide an abundant crop of conches -

a highly valuable mollusc.

The Haenyeo only harvest the conches after the breeding season,

to ensure the harvest remains sustainable.

Choon Geom Kim is captain.

She must decide if it's safe to dive.

Wal Soo Ra is the oldest living Haenyeo.

In fact, she is the oldest diver anywhere in the world.

She is now 94 years old.

The dive captain has decided they will dive.

Conditions are not ideal but the conch season is short

and they must make the most of it.

An experienced Haenyeo can dive to depths of 20 metres

and hold her breath for more than two minutes.

This places significant stresses on the body.

There is a very real risk of blackout,

as the Haenyeo repeatedly travel between the surface and the sea bed.

As they dive, their heart rate slows,

and blood is shifted from their extremities to their core...

..increasing the availability of oxygen.

The Haenyeo benefit from this adaptation,

to enable them to keep working on their long, cold dives.

But it's exhausting work, even for the younger divers.

She may not be able to hold her breath for as long as she once did,

but, at 94, Wal Soo Ra is still capable of diving all day.

The women work together against a rising tide.

The waters here are changeable...

..and the longer they stay, the greater the risk.

But the season is short...

..so the women must persist...

..and reap the harvest while it is there.

Back on the Korean mainland,

deep in the forests of Yangpyeong...

..there are other female workers, reaping a harvest.

Eastern honey bees.

Workers collecting pollen.

They belong to an enormous colony...

..of 30,000 bees.

The colony has made its home here in this hollow tree...

..which offers shelter from the elements.

Inside the tree is a complex and cooperative society.

All the bees are dedicated to the colony...

..at times vibrating their bodies

to produce heat and maintain a perfect temperature

for the next generation.

But the bees are not alone in the forest.

An Asian giant hornet has identified their location.

The hornet studies the nest

before returning to its own colony.

This scout has information to share.

Using an advanced form of chemical communication,

the scout passes on details of the exact location

of the honey bees' nest.

The scout returns.

The bees shake in unison to warn off the hornet.

But this time he is not alone.

The hornets do sometimes eat the bees themselves

but they are more interested in the protein-rich larvae inside.

Individual bees have no chance against the hornets.

Gradually they weaken the bees' defence.

There are many casualties.

But it will take more than this to overcome the colony.

The bees prepare to fight back.

The counterattack is started by a handful of worker bees.

It appears suicidal.

But the bees are programmed to lay down their lives

for the survival of the colony.

And the tables begin to turn.

Bee stings can't kill the hornets.

But they do weaken them.

As the bees gain the upper hand, pushing their attackers back...

..they now release the full force

of their defence for the last remaining hornet.

They swarm, immobilising it.

The bees vibrate,

raising the temperature at the centre to a level

the hornet cannot withstand.

And the hornet is cooked alive.

The bees have developed this unique and effective defence over millennia.

Many more bees than hornets died in this encounter.

But their colony has survived...

..and will continue to thrive here in the forest...

..until the next encounter.

200 miles away...

..the mud flats of Suncheon Bay in the south of the Korean mainland.

During the monsoon, they receive one of the highest

levels of rainfall anywhere in Korea.

It can rain constantly here for weeks at a time.

But it is not the torrential downpours

that have shaped this landscape.

Suncheon Bay is a tidal ecosystem

that is neither land nor sea.

Each day, the tidal waters of the bay withdraw

to reveal over eight square miles of thick mud -

a seemingly inhospitable landscape.

But the local people thrive here,

as they have done for thousands of years.

No modern vehicle can cross the mud.

Instead, the local people get around here on specially designed boards.

It is hard going but the rewards are huge.

The mud of the day is rich in nutrients

and supports one of the most diverse ecosystems in Korea.

Today the mud flat industry is larger than ever before.

Seafood makes up a huge part of the Korean diet.

And much of it comes from Suncheon Bay.

Thousands of tonnes are harvested here every year.

Yet, despite the increase in fishing activity in the bay,

the mudflats are so rich

that they are quick to replenish

what is taken out during the harvest.

Some of the most abundant creatures here

are various forms of mudskipper,

the misfits of the aquatic world.

They spend almost as much time out of the water as they do in it.

And that's possible as long as they remain moist,

allowing them to absorb oxygen through their skin.

There are several different species of mudskipper here.

Shuttles hoppfish is among the smallest.

This male is just five centimetres long,

and he has only just reached sexual maturity.

Now this young hopeful must find himself a mate.

70 miles north is Upo, the largest natural swampland in South Korea.

This prehistoric wetland is home to many rare species,

and it's a protected conservation zone.

In summer much of Upo is carpeted with lilies.

One of the most prolific is the ancient and aptly-named

prickly water lily.

The jacana has developed

exceptionally long toes

to spread its weight across the thin lilies

and create a bridge above the spikes.

But even for jacana, it takes a little practice.

Their reward is an abundance of insect life

on the surface of the water.

As night falls over the wetlands,

another type of predator takes their place on the lilies.

A raft spider.

For an ambush predator...

..location is everything.

She cleverly positions herself where the traffic is busiest.

Highly sensitive to vibrations,

these spiders can detect potential prey

beneath the surface of the water.

But this is no ordinary insect-eating spider.

She has bigger fish to fry.

She is poised, ready to strike.

The first attempt fails...

..and the prey escapes.

Patience, however, is the fisherman's best weapon.

She bides her time...

Success!

The spider immediately sinks its hollow fangs into the prey

to deliver a lethal dose of venom.

And it's over within a matter of moments.

20 miles away is Junam reservoir...

..the site of one of Korea's most spectacular natural events.

A cloud of Baikal teal, all soaring in perfect unison.

Junam reservoir is the largest

migratory bird sanctuary in South Korea.

The lake never freezes,

making it a perfect winter stopover for many migrating birds.

Each year, around a million of these water birds arrive in Korea.

They migrate from eastern Siberia...

..in search of warmer climes.

They fly in dense formations, wing tip to wing tip.

This hypnotic spectacle has earned these visitors a unique place

in the heart of Korean culture.

In this part of the world, many birds are seen as sacred.

One of the most revered species

lives in the mountainous forests of central Korea.

Amongst the dense woodland, an ancient tradition endures.

That of the falconer.

Yong Soon Park has recently captured a goshawk from the wild,

and is crafting a sichimi.

Equipment like this cannot be bought.

Each falconer must learn to craft his own.

It is a part of the tradition.

The feather and bell help to track his bird,

and the bull-horned head shows that the bird belongs to him.

At least, for now.

Goshawks are as individual as we are.

Some are nervous,

others are stubborn.

So the falconer must learn to tailor his approach.

More than anything, falconry requires trust.

Falconer Park has spent many, many hours with his hawk,

to build that bond.

But however strong their connection, it is also fleeting.

HAWK SQUEAKS

HE MAKES CLICKING NOISES

The most important tradition of Korean falconry

is that the falconers do not keep their birds for life.

They accept that a hawk is wild and can never be fully tamed.

HE SHOUTS

The goshawk has short, wide wings,

allowing it to pass through gaps at speeds of up to 40mph...

..and a long rudder-like tail for sharp turns.

That makes it an extremely successful hunter.

In Suncheon Bay, it's the mating season for mudskippers,

and this young male is searching for a suitable mate.

It appears the odds are stacked against him.

In his quest, he must cross open water

to reach a potential mating site on the far side.

There are predators in these waters.

He makes it across, but is not yet completely out of harm's way.

Mudskippers, although hardly considered a delicacy...

..are eaten.

They are also used in Chinese medicine

and there is a profit to be made for this fisherman.

A near miss.

The young mudskipper escapes and moves on to unexplored territory.

Other species of mudskipper can be territorial.

Some are highly aggressive.

He wisely moves on.

Eventually, the young male spots a patch he likes the look of.

Far fewer rivals.

This will do very nicely.

A single female.

He performs his courtship dance.

She seems unimpressed.

But he shuffles a little closer...

..and tries again.

She is much larger,

so this is very much her decision to make.

Just when it looks like the young male's luck has run out...

..she appears to have a change of heart.

He sucks her face...

..and she is not completely put off.

The pairing has been agreed.

But the next stage won't happen in front of an audience.

Their mating will take place below ground...

..safely inside a mud burrow.

North of the mudflats of Suncheon

is a very different but equally rich environment.

60% of South Korea is forested and much of its biodiversity is found

in these ecosystems.

This peculiar-looking creature is a beetle larva.

It is following a trail across the forest floor.

A slime trail...

..left by its intended prey.

The helpless marsh snail produces a foaming mucus

in an attempt to confuse its attacker.

But to no avail.

The larva injects paralysing digestive fluids

directly into the snail...

..and begins to feed.

It may seem cruel...

..but the beetle must feed to fulfil its role in life.

The nutrients it has gained will help its transformation.

Bioluminescent chemicals in its abdomen begin to glow.

It is a firefly larva, and once freed from its casing,

it lights up the dark skies...

..a spectacle South Korea is renowned for.

Proof that in nature,

scenes of great beauty can often conceal a darker reality.

In the southern province of Jeju,

the conch season is drawing to a close.

For many years, the island was known as Geumdo, meaning "forbidden",

because of the treacherous conditions here.

The sea is rough

but the Haenyeo have been diving all day.

There is still an abundance of conch to collect.

The Haenyeo are highly sensitive

to any changes in the underwater currents.

Even a small change down here can signal life-threatening conditions.

But the Haenyeo are tenacious.

Today, despite the increasing risk,

they decide to stay in the water and now, they must work quickly.

Finally, with their nets filled, their work is done.

Exhausted from hours of diving, they are vulnerable.

Having lost one woman to the sea last year,

they know all too well the cost of making a mistake now.

With a final effort, they drag their heavy nets out of the water.

All that remains now is to weigh the day's catch.

The signs are good.

The harvest has been a successful one.

The risks that they have taken have paid off.

But, the day has taken its toll...

..more so for some than others.

The Haenyeo will return to dive again tomorrow.

But perhaps not all of them.

Wal Soo Ra has worked in the waters of Marado for 80 years,

sharing them with the others that live here.

She hopes that the knowledge she has gained will be passed on...

..and that the Haenyeo culture will continue to prosper here...

..existing in harmony with the seas.

The traditional ways of life that endure in Korea today remind us

that people have thrived for millennia,

living harmoniously with the natural world...

..and its many fascinating inhabitants.

In Korea today, as in much of the developed world...

..things are changing quickly.

But wild Korea still has its treasures...

..and its place in the country's heart.