-STEVE BACKSHALL: Whales... - (WHALE HUMMING) ...ocean giants, ancient mariners.

Their songs, majesty and sheer size fill us with joy and awe.

In their vast shadow, a human can feel very small.

(WHALE VOCALISES) They were here long before us... Caring for their young...

Hunting... Voyaging...

But now, we are changing their world.

So I want to see through their eyes, meeting them on their terms to find how their future and ours are inseparable.

I'm exploring our kinship with whales and dolphins.

Once dubbed devil fish, we now know they need our help.

For the entirety of human history, whales have been creatures of myth and legend, shrouded in mystery, with us knowing little of their secret lives.

But now, leaps in technology are offering us a window into their world.

We are entering a golden era of understanding the world of the whale.

Much of that mystery is down to their ocean home.

A place that we humans can only fleetingly visit, and rarely to the depths they can dive to.

But despite our differences, whales are mammals like us.

(SNORTING) And it turns out, we have more in common than you might think.

I'm starting my journey in one of the most remote places in the Atlantic, the Azores.

Searching for the whale that was probably the most misunderstood of all... the sperm whale.

BACKSHALL: There it is!

Full breach!

Sensational!

This is one of the deepest diving creatures on the planet, able to get down to well over 2,000 metres in depth, and to hold their breath up to two hours.

These astonishing animals are also our largest toothed predator.

Mariners both respected and feared them, believing they could swallow fishermen or even boats, whole.

The reality is perhaps even more dramatic.

These leviathans battle giant squid in the darkness of the deep before returning and leaping.

Our whale is breaching repetitively.

It seems to be totally disinterested in us and our boat, completely focused on its task, which gives us the perfect opportunity to get in and swim alongside him.

Whales sometimes react to the bubbles of a human scuba diver.

So it's far better to dive as they do, using just the air of a single breath, or freediving.

Swimming alongside this enormous whale, it's hard to believe that, as mammals, we share a common ancestor.

Its giant form is honed to life in the deep ocean, and so different from my own.

(WHALE SNORTING SOFTLY) But then, our connection is revealed... Just like me, this sperm whale must come to the surface to breathe.

And pretty soon...

I have to do the same.

Wow.

That was incredible!

Underwater is the only time that you get any real sense of the scale of the animal, and also, the power, and the speed.

Being alongside them, they appear motionless, but they can just disappear into the blue.

Their size and strength made it inevitable that humans would fear them and made it easy to treat them as just a simple commodity.

It happened right here in the Azores.

These buildings are the remnants of the factory part of a whaling station.

This was still active when I was a kid.

In fact, the last whale was killed here in the Azores in 1987, when I was at school.

All over the world, sperm whales and others were ruthlessly hunted.

It's said that the oils rendered from their bodies lit the lamps of the Industrial Revolution.

Other parts were used for products, from fuel to fertiliser.

For me as a naturalist, so many of the highlights of my life and my job have been working with animals like this.

And seeing them like that... it's almost impossible to take.

But over time, the brutality of the slaughter became public knowledge, and there was uproar.

People took to the streets in protest.

Governments rallied, and whaling was banned by almost every nation.

Globally, some species are recovering.

Now the majority of nations are no longer hunting them, we've begun a new relationship with whales, where science leads the way.

Whales, dolphins and porpoises are collectively known as cetaceans.

(WHALES SQUEALING) By studying them, we've discovered how social some species can be.

Here in the Azores, I've tracked down a small group of female sperm whales...

Hoping to see this for myself.

In some ways, male and female sperm whales are so different, they're almost like completely separate animals.

The males lead largely solitary lives, heading up into Arctic seas and all the way down into the Antarctic.

The females, though, are a seriously social animal.

Females remain with their birth pod for life.

So this is probably a mother and her daughters.

The rubbing of heads helps remove barnacles, lice and dead skin...

But as with us, touch is hugely important for bonding, perhaps even for reassurance.

With no arms to hug, this is the best way to give and receive affection.

It's moments like that, when you see such tenderness between animals that you start to feel some kinda kinship with them.

You know, even though this is a creature that's 20-odd tonnes in weight, when you see a mother interacting with its youngsters, and them just enjoying the physical contact, all of a sudden, you can see that they have so much in common with us, and it's actually quite an emotional thing.

The more we look, the more we see our own lives reflected.

In some of the other 90 or so species of cetaceans, relationships can be even more complex.

That's certainly true of the friendships, collaborations and rivalries we see in the cetacean we often think of as the most friendly... the dolphin.

BACKSHALL: Since the end of the era of whaling, we've entered a golden age of discovery about whales and uncovered an animal that has a lot in common with human.

(CHITTERING) The remote islands of the Azors are a perfect place for me to dive with them on their ters and explore further.

The diversity of whale and dolphin life here is pretty much unparalleled, and because there are dozens of species that pass through these waters, or that live here, pretty much anything could turn up.

But of all the animals we hoped we might encounter here, there's one I'm particularly excited to come across.

Look at that!

What!

That can't be happening.

These large blunt-nosed dolphis are known as Risso's.

They're often spotted at a distance but are notoriously shy.

I've never even come close to them in the water before.

This one plunge could reveal all sorts of things about their mysterious lives.

I didn't think I would ever see Risso's dolphins underwater, and they are a very surreal sight.

They kind of appear to be white or light grey, but when you get up close you can see that it's scarring criss-crossed all over the head and the body, and that's from fights with other Risso's dolphins, particularly males fighting other males.

Risso's live in all-male group, an unusual thing for whales.

But living in an all-male gang, status is everything, and that's where the scars come in.

It's thought they act like tattoos that visually display an individual's status, with the oldest males being almost completely white.

But this is something else.

On an unseen cue, the whole group turns and comes together.

(BUBBLING) Bubbles, like touch, are tactile, stimulating.

Perhaps this is a moment of group bonding.

Like a team cheer, or a battle cry before hunting.

This form of social bonding was only recently discovered by scientists.

Every time you delve beneath the surface of their social lives, you see something familiar to us.

The word "dolphin" applies to around 40 species of toothed whale and they're surprisingly diverse.

They range from the black and white Commerson's dolphin, which can weigh as little as 30 kilos, to the Amazon river dolphin, which lives in fresh water... all the way up to giant predators like pilot whales... and orca, the largest members of the dolphin family.

I'm crossing the Atlantic and heading to one of the best places to understand their lives.

The Bahamas, in the Caribbean.

Dolphins live in so-called fission-fusion societies.

That means that their groups are always in flux.

So, sometimes they could be flying solo, they could be hanging out with their families or their friends.

Other times they'll come together in pods that could be dozens, hundreds or even thousands of animals strong.

If fission-fusion groups sound familiar, it's because that's just how we live.

Many scientists believe it was the growth of complex societies that drove humans to evolve bigger brains, and, might also explain why dolphins are so clever.

To find out more, I'm heading out onto these Caribbean seas to find one of the most sociable dolphin species.

These are spotted dolphins.

The ones that have the really definitive dappling, those are the mature animals.

The smaller ones haven't got their spots yet, and they're just, like this one here, that's no more than a calf.

But the reason they've come to the front of our boat is that they know pretty soon we're gonna start moving, and that's when things really kick off.

Surfing the bow waves of boats might be more energy efficient, allowing dolphins to swim further and faster.

But that's not the only reason.

Dolphins are nature's thrill seekers.

There is no more pure expression of joy in the natural world than seeing dolphins riding the wave at the front of your boat.

They'll fall into the spray at the bow, and sometimes stay for hours, and then other times, it's just a fleeting dance, and then they're gone.

Woah!

Ho, ho, ho!

Scientists think that playing is a critical part of their development, but in the right situation, they'll look for playmates outside their own group.

Even to people.

But whether or not they want to include me in their game will be entirely up to them.

(DOLPHINS SQUEAKING) Even with this powered scooter, just a couple of flips of those tail flukes and they are gone, there is no way you could ever keep up with them.

So, you have to try and look as intriguing as you possibly can.

There's no point swimming straight towards them, it's all gotta be on their terms, but if you can look like fun, they'll stay and play for hours.

Playing helps practise essential physical skills, like hunting, mating, and avoiding predators, whether you're flying solo or in a group.

But like the rough and tumble of a children's playground, having a large number of different playmates is unpredictable, and can make this learning much more effective.

If they play like us, and hang out in ever-changing friendships like us, could dolphins also share our most complex social skill of all, language?

We know some dolphins appear to use different noises to indicate different states, like courtship, or stress.

Some dolphins also use a signature whistle to identify themselves.

(DOLPHIN WHISTLING) But dolphins don't just hang out with the same species.

(INDISTINCT CHATTERING) BACKSHALL: Kel Sweeting is a scientist who's been studying interactios between two different types of dolphins.

Both found here in the Bahamas.

So, you have this incredible situation here, where you have different species that are sometimes living together.

What can you tell me about that?

Here in Bimini, we have two species of dolphins.

The Atlantic spotted, and the bottlenose dolphins.

Most of the time, if you come upon dolphins, it's a single species group, but sometimes they're together, and they're actually interacting.

And do the spotted and the bottlenose have different use of communication and sound?

SWEETING: Dolphins in general have a wide vocal repertoire.

Squeaks, squawks, whistles, chirps.

They also have postures and gestures, and so there's probably a lot of overlap.

Bottlenose and spotted probably understand each other quite well when we think of communication as a whole.

BACKSHALL: We don't yet know precisely what dolphins might be saying to one another, but science tells us it's more complex than we thought.

If dolphins are nature's chatterboxes, other whales do things differently.

In the next part of my journey, I want to find out why some whales want to be heard hundreds of miles away, and how their sound-sensing powers can put whales in danger.

BACKSHALL: The more we understand whales, the more we discover we have in common.

Modern science and technology allow us to appreciate the whales' underwater world in ways we never thought possible.

Some of the biggest breakthroughs are in long-distance whale communication.

To find out more, I've crossed into the Pacific Ocean to the paradise island of Tahiti in French Polynesia... Where the seas resound with a familiar and bewitching tune.

The song of the humpback.

(WHALE HUMMING) We often think of our seas as being a silent world, but the truth is that's very rarely the case, and certainly not here in French Polynesia during humpback breeding season.

This is a hydrophone, which is a highly sensitive underwater microphone.

So, let's drop it in and see what we can hear.

(WHALE HUMMING) Oh, there it is.

(WHALE HUMMING) That is beautiful.

Male humpbacks sing long and complex songs, sometimes lasting hours at a time.

Scientists suggest the songs may be advertisements, sea-borne serenades showing off to potential mates.

One of the most amazing things about whale song is sound carries about four times faster in water than it does in air, and it can travel further, too.

So, whales can be communicating with each other across entire seas.

The crooning male could still be many miles away, but I've found some females close by, and I want to know if they're listening.

(WHALE HUMMING) Down here, I can hear the song without a microphone.

These females are surely aware of his love songs.

But, are they impressed?

Females may not sing...

But they are far from silent.

Her giant pectoral fins are the longest fins, and indeed limbs on the planet.

BACKSHALL: Slapped on the surface, they turn the ocean into a giant drum.

The sounds of vibrations carry all around.

And may be a reply to the male song.

Humpback courtship is intense and can turn violent.

It's best not to linger with huge limbs and tails flailing through the water.

The humpback is the most tunefl and best known whale vocalist.

But many others also call long distance.

The Blue whale, the largest animal ever known to have lived, creates deep sounds too low for our ears.

This infrasound travels over 800 km.

Whales have evolved in this acoustic realm, so they also use sound to navigate... (SNORTING) ...and to hunt using echolocation.

Despite their lack of external ears, they have other means for receiving and processing sounds.

With twice the auditory nerve cells of humans, most can hear a far wider range of frequencies.

But highly sensitive hearing has consequences.

They cannot escape noise and the soundscape of the sea has changed.

(ENGINE WHIRRING) We're only now starting to understand quite how vital sound is to whales and dolphins.

It's possible they may have language every bit as sophisticated and complex as our own.

What we do know is how much they need silent seas and that we, as humans, are turning them into unbearably noisy places.

(ENGINE WHIRRING) Since the 1950s, ocean sound may have doubled every decade.

Shipping... drilling for oil... and other human activities create a constant background drone.

(HORN HONKING) Other sounds are much more violent.

Explosive charges in the hunt for fossil fuels... (EXPLOSION) ...and naval blasts can destroy a whale's hearing.

As they try to flee the noise, they may surface too quickly, suffering decompression sickness.

Noise pollution might even lead to a tragedy that kills thousands of whales and dolphins.

Stranding.

Probably the worst affected species is the pilot whale.

(WHALES CHITTERING) These live in close-knit family groups that roam the globe, hunting for deep sea squid.

And where one goes... the others follow.

But if noise exposure causes one to be driven ashore by deafness or disorientation, their close bonds mean the rest of the family won't leave it behind.

Without assistance, the whole pod can perish.

I'm heading to the British Isles and the rugged coast of South Wales to find out what can be done.

With stranding incidences increasing worldwide, the way we deal with them has never been more critical.

All around the world, volunteer groups are offering training to teach the essentials of rescue and whale first aid.

This whale is just a replica.

But in a real life stranding, a fast response would be critical.

Cetaceans have evolved over millions of years to live in the water to have their body weight supported.

The second they're on land, they are on borrowed time.

Without the support of the water, a whale's organs will collapse.

They're also unable to regulate their body temperature and will quickly overheat.

So it's vital to know the best way to keep a whale cool, and it's fragile skin safe from injury, while we work to return it to the sea.

Even with a whale, this sort of size, it's still going to weigh well over a tonne.

There's no way we can lift it.

So we have to rely on the tide coming back in.

-Everyone ready?

-Yes.

One, two, three.

Go.

BACKSHALL: When emergencies happen for real, like this one in New Zealand, we know this huge effort can work.

And hundreds of whales have already been saved by volunteers working in this way.

If this was the real deal right now, you'd be freezing cold and exhausted, but coming out of the sea having seen a whale head back out and knowing that your hard work made that possible, which I think would be just about the most satisfying thing you could ever do.

Despite efforts to protect the, changes in our oceans are putting whales and dolphins in danger.

But to keep them safe, we need to understand them.

In the next part of my journey, I want to seek out the people forming unique bonds with whales.

And ask what we can all do to give whales and dolphins a brighter future.

Humanity has come a long way in our relationship with whale.

But because so much of their lives take place far from land in deep water, we still have a lot to learn.

For most species of whales and dolphins, simple things like breeding, giving birth and even feeding have never been seen.

So much of their world is a mystery to us.

And because their realm is effectively off limits, it takes dedication and resourcefulness to unlock their secrets.

Here on the island of Mauritius in the Indian Ocean, one pioneering team have forged close bonds with a special pod of sperm whales.

My name is one Rene Heuzey.

I am an underwater cameraman.

And I'm filming the sperm whales in Mauritius since 12 years.

When you're there from 12 years with the same family, it's like your family.

(WHALE CHITTERING SOFTLY) For me it's very magical.

It's amazing.

Because I am just a little human.

BACKSHALL: Rene has been diving with the same sperm whales for so long, that they've learned to accept his presence.

He can identify each individual by name.

And knows their unique histories.

But of all the whales in the group, there's one he's most eager to see... Chesna.

These first shots of her as a newborn were captured six years ago.

Since then, Rene has dived alongside her over and over again.

Today is the first dive of the year.

And Chesna has come to greet him.

HEUZEY: I would like to know one thing very, very important.

I would like to know how to communicate between sperm whale and the human.

BACKSHALL: Knowing many whales use bubbles to communicate, Rene has adapted his dive regulator to mimic their emissions and uses it to signal his recognition.

Almost immediately, Chesna signals back.

(CHESNA CHITTERS SOFTLY) HEUZEY: When we are looking eyes to eyes... and for me, it's a magical moment and I have a lot of emotion because...

I recognise Chesna and Chesna recognises me.

She accepted me.

BACKSHALL: This gift, to be able to get to know individual whales, has benefits for science.

It's enabled Rene and his colleagues to create the first detailed whale family tree.

And this is more than a family, it's a community.

This is a baby sperm whale.

He's tiny.

And while he's so small, almost totally dependent on his mother.

Because he can't yet dive to any depth when she descends into the deep to feed, he must remain on the surface.

But he isn't abandoned.

His mother has left him under the watchful eye of a babysitter.

She keeps him close and defends him from predators.

But that's not all she does.

After an hour of hunting, his mother returns to the surface to breathe.

Exhausted, there's only one thing she wants to do... Rest.

Hanging vertically to sleep.

He tries to suckle, but without success.

But her baby needs to feed.

He tries his luck with the babysitter.

She isn't his mother, but can be... a wet nurse.

Milk flows from a concealed nipple in front of her tail.

This has rarely been filmed.

Caring for the infants of others, or alloparenting, is incredibly rare in the natural world.

Less than 3% of mammals do it.

Among them, of course, are humans.

With every piece of science that emerges, whales look less like ominous and mysterious ocean devils, and more like our close mammal kin.

Nowhere has the human-whale relationshp changed more dramatically than in the peninsula of Baja California in the eastern Pacific.

This was once the site of bloody battles between man and whale.

Whalers would target calves and the mothers would smash their boats to pieces, earning them the name, "Devil Fish."

Even when whaling was banned here in 1947, fishermen continued to fear the whales for decades.

But not any more.

(AGUILAR CAMACHO SPEAKING) BACKSHALL: As well as being a fisherman, Daniel has a special licence allowing him to take visitors out into the lagoons to go looking for whales.

But they never have to look for long.

AGUILAR CAMACHO: We had a whale at 12 o'clock.

BACKSHALL: These grey whales could be descendants of those that survived the era of whaling.

Despite their gruesome past, the whales don't smash the boats or flee.

Instead, they seek them out.

AGUILAR CAMACHO: Another whale is coming this way.

WOMAN: It's got a calf.

It's got a baby.

BACKSHALL: The mothers even encourage their babies to meet their first humans.

(WOMAN 1 LAUGHING) (WOMAN 2 SPEAKING SPANISH) (LAUGHING) It's so playful.

You can see, like, the mom is just pushing the baby.

So she's letting us play with him.

WOMAN 1: She's just spectacular.

It's so... immense to have them so close to you.

BACKSHALL: San Ignacio was once a slaughter site for whales.

Now, the fishermen are their guardians.

Numbers of visitors are strictly limited.

And their nurseries are protected by law.

WOMAN 2: I think we are honoured to have these whales in these lagoons.

And this bond began with a fisherman, no?

BACKSHALL: Grey whales are migratory.

Soon these infants will have to leave this sanctuary and head into unprotected seas.

But for now they're safe.

San Ignacio is an inspiring tale of how human attitudes to whales can change in just one generation.

But if we want whales to have a future, we need this to be repeated everywhere.

For whales and dolphins to flourish, they need safe havens... a refuge from our fishing, our shipping and our noise, where we safeguard their food, their nurseries and everything else they need.

Currently, these make up just a tiny fraction of our seas.

But there is hope... on the horizon.

In 2023, the United Nations came up with a plan to protect 30% of our oceans by 2030, the biggest conservation win in my lifetime.

If we care about our whale and dolphin cousins, it's up to us to make that happen.

Especially, now we know how much we have in common.

When we set out to make a series about whales, we knew we were in for a challenge, with some species almost impossible to see, let alone film.

As the stopping off point for all sorts of Atlantic marine life, the Azores is a hotspot for whales.

These islands play host to dozens of whale species, either resident or passing through.

As such, they were once a focus for whaling.

But knowing they're around is just a start.

Some whales travel fast and only surface for a few minutes at a time.

So for director, Ellen Husain, it was critical to be in the right place at the right time.

We're at their mercy.

They're such big animals.

They can move so fast compared to us.

We just have to hope they allow us to film with the.

BACKSHALL: When we finally found our first whale... HUSAIN: Emanuel, let us know.

(SPEAKING PORTUGUESE) 7 o'clock.

Black devil.

BACKSHALL: ...local guide, Emanuel Goulart gave us the signal to enter the water.

GOULART: You want to dive now, go now.

Go!

Here.

I go here.

BACKSHALL: We had special permission to dive with the whales here, which are protected by law.

But even giant ocean predators can be surprisingly sensitive.

I had a bit too much of a splash going into the water.

And the whale heard it and turned away.

BACKSHALL: We needed to get to know each whale and assess their mood, before getting the camera team in place.

And the techniques used to find whales in days gone by, still work.

Our method for finding whales basically hasn't changed in 100 years.

We're standing here looking out to the horizon for the blows or the spouts from the whales.

But we have one added advantag.

Up on the hillsides around us in the exact same lookout spot, as were used during the era of whaling, we have spotters.

The one difference is if they see whales, they get on the radio and tell us where they are, as opposed to mobilising the boats to head out to hunt.

We also used another whaling technique to hone in on our targets.

Calves are not as adept at diving as their mothers, so they have to stay at the surface.

And because of that, if you can keep an eye on one of the young calves, you've always got a kind of focus point for where the adults are eventually going to be.

This method gave camera operator, Rob Taylor, the chance to capture one of or most memorable encounters.

This looks good.

This is very good.

-You set, Rob.

-TAYLOR: Uh-huh.

HUSAIN: Okay, divers in.

WOMAN: Okay, copy that.

BACKSHALL: It really is quite something.

It kind of feels just like you're watching a human mother having a cuddle with their bab.

They just seem so calm, so chilled out.

Clearly just relaxing at the end of the day.

Very, very beautiful.

With long days out at sea on the North Atlantic, anything could happen.

Spotters had directed us south to a feeding gathering.

But there was a surprise in store.

We've just had to stop because we're surrounded by a pod of Risso's Dolphins.

Normally Risso's are super shy.

They disappear at the first sin of a boat or a person, but these are just hanging out at the surface.

This left us with the dilemma.

Getting footage of Risso's would be a real coup.

But if we wasted hours trying and didn't succeed, we'd have missed the big action down south.

Cameraman Rob was undecided.

You don't normally ever try to film Risso's dolphins because you can't film them, essentially.

Ten o'clock, five metres from the boat.

Straight down, Rob.

Straight down.

HUSAIN: This looks good.

BACKSHALL: Against all the odds, our gamble paid off.

The Risso's cruised by, seemingly oblivious.

And we captured something very special indeed.

That was completely surreal.

That was amazing.

Unbelievable.

(LAUGHS) We are very, very happy.

I've never, ever seen Risso's dolphin behaving like this at all.

I mean, that was crazy.

They... yeah.

-I mean... -(CREW LAUGHING) They don't... they don't do that.

BACKSHALL: We followed in the footsteps of whalers, to explore our close kinship.

And by pure chance, captured a moment that adds to our understanding of these enigmatic animals.

(ENTHRALLING MUSIC PLAYING)