Original subtitles

[water rushing]

[thunder rolling]

[dramatic music playing]

[penguins squawking]

[Barack Obama] The Falkland Islands.

This exposed South Atlantic outpost is blasted by relentless winds

and year-round waves.

They stir up nutrients,

stimulating algae to grow,

which turns the sea a rich Atlantic green.

[delicate, serene music playing]

Calm between storms doesn't last long.

So, if you live here, you take advantage of any break in the weather.

[rollicking surf rock music playing]

Commerson's dolphins.

They love to surf.

Their team colors

are a form of camouflage,

breaking up the outlines of their bodies.

[surf rock trailing off]

These four-foot-long dolphins never miss an opportunity to play.

And this serves a greater purpose,

keeping their big brains busy

and connecting them as a pod.

[echolocation chirrs]

[menacing music playing]

But they're not the only surfers here.

A sea lion.

[guttural bellowing]

He's the resident bull.

This is his break.

He'll chase off anyone he can.

But they're not intimidated by him.

[buoyant, rowdy music playing]

For the dolphins, it seems like a chance to have more fun.

Today, it's a game of catch me if you can.

[exuberant chase music playing]

[sea lion honks]

And when the sea lion gives up the chase...

[peculiar, inquisitive music playing]

...they come out of hiding to find him.

Playing like this keeps them all at the top of their game,

physically and mentally,

bonding them as a team.

[sweeping, uplifting music playing]

For many creatures that live in the wild Atlantic,

teamwork is the key to survival.

[majestic music playing]

The global ocean current flows

from the Indian Ocean into the South Atlantic,

the start of a 10,000-mile, four-year journey north.

[wave roaring]

Through some of the roughest seas, and biggest waves, on the planet.

Our voyage begins at Africa's southern tip,

where the waters of the Indian and Atlantic oceans collide.

[music intensifies]

A place known by ancient mariners as the Cape of Storms.

Storms that create huge swells that pummel the coasts.

[distorted whooshing]

[muffled turbulence]

Yet, beneath the fury, there can be pockets of calm.

Dense forests of kelp fringe the coastline.

They absorb the waves' energy, taming this wild ocean.

[elegant, refined music playing]

And hidden within one forest glade is

the nesting ground of a passionate gardener.

A sea bream,

busy tending his patch.

[zippy, upbeat music playing]

He's maintaining a well-polished rock,

free from weeds and sand,

designed to attract a female to lay her eggs.

But he's got competition from other males.

To stand out from the crowd, his plot must be perfect.

It's all about keeping up appearances

and removing anything that might make it messy.

Hermit crab.

Seaweed.

[resounding thump]

Move along, shark.

This starfish has got to go...

over the neighbor's fence.

[eccentric music playing]

Wasn't me.

Hmm.

His neighbor doesn't seem too pleased.

I believe you dropped this.

[mischievously confrontational music playing]

Nope. All yours.

It's not every day you get a courtside seat for starfish tennis.

This could go on forever.

But they've both made their point.

Time to ditch the starfish and get back to work.

With his rock garden nicely polished...

[thoughtful, elegant music playing]

...and with egg-laden females passing overhead,

he can, at last, put on a show.

He draws attention to his plot.

She likes what she sees.

And with a little encouragement,

she lays her eggs.

Now his sole focus is to guard them until they hatch.

[muffled turbulence]

But conditions in the South Atlantic are unpredictable,

and can deteriorate quickly...

churning the water...

and carrying the delicious scent of eggs far beyond his kelpy glade...

[chilling, alien music playing]

...attracting a swarm of hungry brittle stars.

[unsettling music intensifies]

No one fish can defend his patch against an army.

It's time for neighbors to put aside their differences.

They'll need to work together to save their eggs.

[tense music playing]

Their squabbles are quickly forgotten in the face of a greater threat.

[plucky, hopeful music growing]

[music swells, trails off]

Only by banding together can they defend their eggs

against the brittle star invasion.

[shimmering, wondrous music playing]

This busy little bream's work is almost done.

Because just two weeks later,

the day has finally come for his babies to hatch.

They'll be carried away on the great current,

to settle in the many kelp forests that define this restless coastline.

[wind rushing]

The wildest weather in the whole South Atlantic is found

where the winds are strongest on the other side of the ocean.

South America's Cape Horn.

Storms here are relentless,

and it's getting even wilder.

With the growing climate crisis, winds are intensifying year after year.

[winds whistling]

It takes special skills to hunt in Patagonia's increasingly rough seas.

Orca are the top predators here.

[foreboding music playing]

There is nothing they won't take on.

Even a full-grown elephant seal...

[rumbly braying]

...is no match.

But adult elephant seals only come to this coastline to breed.

To stay here year-round, the orca must find other prey.

[echolocation squeaks]

Their pod is led by Grandma.

She's almost 50 years old,

and has spent her life mastering this coast.

Now her eye turns to the beaches...

where young seals and sea lions haul out when the sea is too rough.

[colony braying]

Despite the risk of big waves leaving them stranded,

these orca must take a chance...

and hunt on the beach.

[music intensifies]

[seal colony clamoring]

If she gets stuck, she could die.

[braying]

Very few orca families are known to hunt like this.

It's a technique she learned from her mother, and must now pass on.

Grandma needs somewhere to teach them in safety,

so they don't become stranded.

As their instructor, she guides her young team to a very special place.

A sheltered lagoon,

safe from the dangers of the waves.

[gentle, pensive music playing]

This beach-hunting academy

is a place for her latest recruits...

[rousing, spirited music playing]

...to raise hell.

[adventurous music rising]

[slick electric guitar riff playing]

[burst of echolocation]

[music intensifies]

[music trails off]

[seal bleats]

The students have all the confidence of youth.

But, lucky for this pup,

they still have lots to learn.

[quirky music playing]

Their instructor leads the way.

"Follow me."

Picking the right beach is essential.

The first lesson today?

Angle of attack.

If the slope is too shallow,

they run aground and fall short of their target.

Because it's so dangerous,

beginners are encouraged to have a wingman,

someone to help them if they get stuck.

Time for lesson number two.

Stealth.

Grandma runs fin-hiding drills.

[echolocation squeaks]

They need to learn to patrol in formation while keeping their dorsal fins submerged.

But they also have to be quiet.

[bubbles burbling]

Best hold your breath.

Time for a full-blown demonstration.

[quirky music continuing]

The aim?

Poke that seal.

[seal bleats]

To advance, the recruits must put all their lessons into practice...

which proves just how tricky this actually is.

Too slow.

[bleats]

[huffs loudly through blowhole]

Too loud.

[cheeky music playing]

Nice speed, but wrong target.

They're making progress,

remembering their lessons and learning from their mistakes.

But they'll still need expert guidance.

Grandma sets up the perfect strike.

She'll call it in with the nod of her head.

[intense music building]

It's the closest this student has come, and a big step towards graduation.

[spirited, rousing music playing]

Training for such a dangerous mission can take seven years.

[echolocation trilling]

No other predator takes so long to earn their stripes.

A set of skills so complex

that it's only possible thanks to years of teamwork,

and the wisdom of Grandma.

Towards the equator,

the winds drop and the waves become smaller

as the great current flows northwards,

where, under the oppressive heat,

the ocean's wild character appears to mellow.

[lilting, serene music playing]

And the Brazilian coastline gives way to forests of salt-tolerant trees.

[effusive birdsong]

Mangroves.

One of the current's greatest hitchhikers.

They evolved in Southeast Asia,

and by riding the current have spread throughout the tropics.

Creating vast tracts of tidal forest...

like here, in the Amazon.

The world's longest stretch of mangroves.

It opens up feeding grounds to one intrepid fish.

[bright, quirky music playing]

A four-eyed fish with an appetite for adventure.

She and her team of explorers are eager to get into the forest.

But it's low tide, and they're stuck at the coast.

The equatorial sun makes the shallows too hot for most fish.

As the tide turns...

and the water floods in,

they're off.

[rousing, adventurous music playing]

They don't just swim.

They can skip.

[keening, ominous music playing]

It's safer to stick together.

It's a very different world in here.

In these mangroves, their unique eyesight comes in handy.

Despite their name, four-eyed fish only have two,

but with a remarkable split across the pupil,

allowing them to keep half an eye on any dangers lurking below,

and the other half peeled for opportunities above.

[shimmering harp glissando]

[rhythmic pecking]

In this forest, you don't know where your next meal is gonna come from.

Termites.

Mmm, delicious.

They might be tasty,

but there's an even bigger prize waiting for those who are adventurous enough

to follow the tide

to the furthest extent of the ocean's reach,

over a mile from where this small fish began her jungle adventure,

in search of a hidden delicacy

only accessible twice a day.

These mangrove crabs must reverse into the seawater to refresh their gills.

She only has minutes before the tide will start dropping.

[tense music playing]

[frantic, whimsical music playing]

Got one!

The ultimate reward for going where few fish dare.

All too soon, the tide turns,

and the expedition team must retreat to the coast,

or risk being left high and dry in the baking heat.

[sweeping, serene music playing]

Just as the Atlantic influences life in the Amazon,

the largest river in the world has its own effect on the ocean.

Delivering over a million tons of leaf litter

and rich river sediment every day,

transporting precious rainforest nutrients,

swept along by the current,

2,000 miles up the coast of Brazil.

Delivering them to the jewel of the Atlantic Ocean...

[vibrant calypso music playing]

...the Caribbean Sea.

We're drawn here to enjoy its beauty and its warm waters.

Soft corals thrive in the enriched current around the island of Bonaire.

It's not easy to get noticed in this coral carnival.

And when breeding time comes around, you need to stand out from the crowd.

[music trails off]

One bright spark waits until dark for his chance to shine.

He's not alone.

[shimmering tones crackle]

[delicate, wondrous music playing]

This magical light show is the synchronized mating display

of one of Bonaire's smallest reef residents.

A tiny crustacean called an ostracod.

Each one smaller than a grain of rice.

Yet, by mixing two highly reactive chemicals inside his body,

a male can create chains of light

bright enough to guide a female to where he is waiting.

The males swarm together, taking turns switching their lights on.

Collaborating like this allows each of them

to hold back some chemicals for emergencies.

And they'll need 'em.

[dark, foreboding music playing]

Cardinalfish are inch-long plankton predators that come out at night.

But ostracods are armed with a secret weapon.

[shimmering tones crackle]

The chemicals taste foul.

So, the fish spits them out as fast as it can.

And, to make matters worse,

now the cardinalfish glow in the dark...

becoming an easy target

for a nocturnal killer that stalks these reefs.

[menacing music building]

The lionfish.

Lionfish are an invasive species

accidentally brought by humans from the Pacific Ocean 40 years ago.

With no natural enemies,

their population has spiraled out of control,

wiping out countless small reef fish.

But they aren't the only pressure humans have put on these reefs.

The climate crisis is causing the Caribbean to heat up.

Over the last 40 years,

a rise of just one degree has threatened the survival

of these temperature-sensitive reefs.

It's been enough to turn this shallow sea into a simmering pressure cooker.

To make matters worse, this cooker is ready to blow.

[storms raging forcefully]

Increasing heat means the most violent hurricanes are becoming more frequent,

just as heat stress weakens the coral, making them more fragile.

They can't withstand this combination of rising temperatures

and increasingly devastating storms,

which so far has led to the tragic loss of 80% of the Caribbean's coral.

[tense music playing]

For many, losing the reef means losing their home.

[somber tone ringing]

For those that can swim their way out of trouble, there is an escape route.

The great current is squeezed out through a narrow gap,

the Straits of Florida,

that act like a nozzle on a hose,

forcing the current to flow with 30 times the power

of all the earth's rivers combined.

Now known as the Gulf Stream, it's the ocean's fastest current,

spreading heat across the North Atlantic.

Taking just a month to flow from Florida all the way to New York.

Where its warm waters fuel vast plankton blooms,

which feed huge shoals of species

that had once been overfished to the brink of extinction.

Menhaden.

But now, with improved fishery management, they are bouncing back.

[stately, sweeping music playing]

Even here, off Long Island, New York.

[birds cawing]

Where they need to stick tightly together,

because the warmer current now brings packs of Caribbean sharks

further north than ever before.

[dark, menacing music playing]

But despite their numbers, menhaden are not easy to catch.

[spirited, determined music playing]

They have lightning-fast reactions and their scales are highly reflective.

Together, they create a mirror-ball effect that dazzles predators,

bringing a new spectacle

to within yards of our beaches.

[music trails off]

Flowing strongly from North America,

the current widens, spreading heat across the ocean.

One branch heads toward Northern Europe.

And the other runs east,

on a course that takes it to a chain of tiny islands.

The Azores.

[sweeping, majestic music playing]

Home to the highest peak of the Mid-Atlantic Ridge.

Rising more than 27,000 feet from the ocean floor,

straight into the path of the global ocean current.

Causing deep-sea nutrients to well up to the surface.

Providing rich feeding grounds

for any creature that can reach this mid-ocean outpost.

[tranquil music playing]

The warming current has recently opened up the Azores

to this newcomer from the coast of Africa.

[imposing, mysterious music playing]

A whale shark.

Fifty feet long...

and weighing over 20 tons.

The biggest fish alive today.

In the last 15 years,

the water has warmed enough for them to become frequent visitors.

[eerie, shimmering music playing]

She'd eat these little snipefish if she could,

but in this three-dimensional space,

they can easily out-maneuver her.

Their safest place is above her.

Keeping her close while avoiding that mouth.

This team of little fish might have escaped for now,

but you don't get to be the biggest fish in the sea without a trick of your own.

She has the largest inner ear of any animal,

giving her extraordinary hearing.

And she now turns that sense to her advantage

by homing in on the rumbling sounds of a distant commotion.

[low, distant rumbling]

This school of fish is being demolished

by giant bluefin tuna weighing up to 1,500 pounds.

The size and speed of a racehorse.

But she's not here for the bluefin.

She's here for the smaller tuna that hang around the edge.

Albacore, bigeye and skipjack.

At under two feet long, they're out-competed by the bluefin.

So, they're still hungry,

and always on the lookout for a new opportunity.

Just what she needs.

They know that joining forces with a whale shark

can lead to the biggest feast of all.

She detects another disturbance

and leads her tuna team to intercept.

[dramatic music building]

As they close in, the small tuna charge ahead

and attack.

The little fish immediately descend on her,

looking for refuge.

But this time, the tuna won't let them find it.

They drive the smaller fish up,

trying to trap them against the surface.

She holds back while the tuna corral them tighter and tighter together.

[dramatic music intensifying]

Creating an immense, twisting fishnado.

[frenzied squawking]

Pinned against the surface,

the tuna can now pick them off one at a time.

And this is what she's been waiting for.

Thanks to her roundup crew, she can finally eat her fill,

swallowing hundreds with each mouthful.

She's made the most of the new opportunities

in today's fast-changing Atlantic.

From the Azores,

the bluefin tuna follow the warm current

to their breeding grounds in a secluded sea.

The Mediterranean,

where its once fish-filled waters now look very different.

[foreboding music playing]

Fish farms.

Over the last two centuries,

we have changed parts of the Mediterranean beyond recognition.

Like many places across our oceans,

industrial technology has allowed us

to reach further and delve deeper than ever before,

fishing beyond what's sustainable.

We now increasingly raise schooling fish in farms,

turning their natural team-living to our advantage,

like the sea bass and sea bream inside these nets.

[somber music playing]

Depleted wild fish populations

have driven a family of hungry bottlenose dolphins here.

Outside the nets, wild fish seek out the company of the captive shoals,

as they feel safer together.

But it provides the dolphins with an easy meal.

[echolocation trilling]

Little of the great current flows through the enclosed waters of the Mediterranean.

So it heats more than the open ocean,

leading to greater evaporation and a saltier sea.

Even these farmed fish will struggle to grow

in waters that are increasingly hostile to life.

Is this a glimpse of the future for all our oceans?

And if so, is this the future we want?

For the fish...

for their hunters...

and for ourselves.

Temperatures aren't just rising in the Mediterranean.

Over its four-year journey, traveling the length of the Atlantic,

the great current has accumulated a vast amount of heat,

carrying enough warmth to create a milder climate across Northern Europe,

raising temperatures by up to 20 degrees Fahrenheit.

[intense, overwhelming music playing]

Out at sea, this fuels extreme weather.

Today, conditions in the North Atlantic are becoming wilder.

And surviving winter on the open ocean is getting harder.

[intense music trailing off]

[somber, pensive music playing]

Here in Iceland, increasingly wild conditions are enough to test

one of the strongest relationships in the entire Atlantic.

[lilting, serene music playing]

This puffin is waiting for his lifelong partner.

[cawing]

His one true love.

He is just one of 100,000 waiting for their mates to return home

after eight months apart.

His partner is still far out at sea,

hunting and building up her strength for the nesting season.

So, he better get their burrow ready.

[cheeky music playing]

For male puffins,

the first chore is a little spring cleaning.

They only have one chick a year, so everything must be just right.

A few soft furnishings...

and he's ready to show off his work.

[soft, pensive music playing]

But she's nowhere to be seen.

He just needs to be patient.

In the ten years they've been together,

she's never let him down.

But this devoted puffin can't just sit around.

[wind rushing]

After all that home building, he's earned some time off.

[gentle, eccentric music playing]

And it looks fun.

Especially when the wind picks up.

[eccentric music building]

All around him, happy couples are reuniting,

but there's still no sign of his special someone.

[thunder rumbles]

[plaintive yawp]

Until recently, puffin pairs would return within days of each other.

But depleted fish stocks and worsening winter storms

make fishing harder.

And his mate won't leave the fishing grounds

until she's ready to produce an egg.

Some females no longer return home at all.

[delicate, enchanting music playing]

Finally!

[caws]

After eight long months apart.

[knowing yawp]

[sweet, cheery music playing]

Surely one of the Atlantic's most faithful partnerships.

[caws]

Now, onto the important business of making a puffling.

For these puffins, and for all life in the increasingly wild North Atlantic,

the warming ocean presents huge challenges.

But, beyond our gaze, nature is responding.

Fish are on the move, in search of a new home.

Surviving populations of cod,

capelin,

and tuna

are swimming further northwards,

moving with the global ocean current

towards the fastest-changing ocean of all.

Next, the current surges into the Arctic Ocean.

[stirring, adventurous music playing]

Bringing with it warm water, which is thinning the ice

and opening up this once-impenetrable ocean.

To stay alive, everyone here must go to new extremes.

[quirky outro music playing]