Compilation 1 Amazon Abyss

The Amazon - a wilderness teeming with wildlife.

But one part is still totally unexplored - under the water.

Hidden in the river lie some of the fiercest and strangest creatures on Earth.

Man may have walked on the moon, but no-one has journeyed

to the very bottom of the Amazon.

Until now.

An expedition is searching for the animals hidden in the depths.

We're looking in places that no-one has looked, we have the ability

to see and film things that no-one has ever seen.

We've not just scratched the surface of the Amazon, but we've gone beneath

it and we are bringing back stuff that is gonna make people go "wow".

But the world's greatest river doesn't give up her secrets easily.

Manaus, in the heart of the jungle, bristling with sailors and river traders.

It's Day One for our explorers.

They're some of the most experienced divers in the world

but they're going where no-one has ever dived before.

For the next five weeks this boat will be their home.

Their mission - to take BBC cameras to this last

great unexplored habitat in search of unique creatures of the deep.

The diving's led by Mike deGruy - professional cameraman,

veteran of The Blue Planet and a hundred other wildlife films.

We really are on a wonderful expedition, we have the opportunity to take all of this

gear and film things nobody's ever seen, nobody's ever heard of, and we're really gonna do it.

Also on the dive team, explorer and naturalist Kate Humble.

Just the most beautiful boat,

I feel like I'm about...

to take part in "African Queen".

Their challenge is formidable.

The Amazon hides its creatures in waters so dark

that no explorers have ever succeeded in penetrating its depths.

Their journey will be through the richest rainforest on the planet - a jungle where a million species hide.

But their adventure will take them to the Amazon

no-one has seen before - beneath the surface of this immense river.

4,000 miles long. In places wider than the English Channel.

It would take 100 years to explore the 5,000 tributaries -

they have just one month.

The multi-national team of scientists and divers will have to overcome storms and setbacks

to discover species new to science, film underwater giants, and track down primitive flesh-feeding fish.

Their 2,000-mile journey will ultimately lead them to dive a black hole in the heart of the Amazon

where with underwater robots they hope to find creatures hidden in the abyss.

I'm Kate...

-Kate.

-Kate's an experienced diver but like the rest of the team it's her first time in Brazil.

Says Kate on the door.

This is really gonna be my first rainforest experience and, um, and

all you hear about is the enormous numbers of diseases that you can get.

Mike's made more than 5,000 dives in every corner of the planet.

As far as difficulty is concerned, this ranks right up there,

other areas like Antarctica, under the ice has its own set of problems,

-but these are unique problems.

-Everything kind of falls apart, nothing heals up properly,

you know, one little snag on your finger will mean that your finger will probably have to be amputated.

On a good day, the visibility is terrible,

we don't know where we're going, we have no reference material, and divers in this area, plus,

there are animals down there that could kill you.

The anaconda

grows to over nine metres long.

And the caiman, weighing in at a quarter of a tonne...

Over the next month, the divers will come face to face with both of them.

The expedition has two local guides who know the risks better than anyone.

Samuel Basilio and Eduardo Gomez are briefing the divers.

Anacondas maybe just break your leg or arm, or your body, easily.

They may kill you.

I recommend that everybody buy and have a knife - a very sharp one.

Don't be too confident when you get in the water, cos that's when the big

accidents happen in the Amazon, even with us.

You have to assume that an animal that has evolved in water this murky has evolved a way of detecting

a 6ft body down there.

So you know in the back of your head that they know you're there.

You don't know they're there.

And that puts them at a big advantage.

And I don't necessarily like that.

My head says, of course there are risks, and play it carefully, but my heart says, great.

I just want to do it. I'm not thinking about - is it dangerous?

There are three boats on the expedition - one for living,

one for support and one for diving.

Their first mission is to travel to a remote tributary of the Amazon -

the Rio Ariapiuns.

The scientists believe that it's home to many rare species.

Even if you do that, I still can't...

As they draw near to their destination, every second is spent preparing the equipment.

Safety is everything.

Most important of all, they must be able to talk to each other underwater.

It could save their lives.

Every single person underwater can talk to each other as well as talk

to the boat, which is where Mike will be with our topside comms unit

and he'll be able to talk to us, and we'll have great communication,

and I personally feel that that communication is the key to the safety of this operation.

The expedition has reached the first dive site.

The whole team has focussed on the preparations and the gear has been checked and checked again.

In these conditions, there's no room for error.

The air is clammy and hot.

The river will be just as warm.

The aim of the dive - to discover just how much can be seen underwater.

It is a step into the unknown.

Despite the heat, for their own safety, they must be covered from head to foot.

There's no way I'm not going in without all this protection, having heard what there is in there.

Right.

As they descend, the divers discover a different world.

The water is heavy with sediment and they quickly lose sight of one another.

Anything could be swimming past them, and still not be seen.

The state of the art diving gear allows them to stay in the water until night is fallen.

But they still haven't seen a single creature.

Are you all right, Kate?

It was so murky, I had a torch held to my computer,

and I couldn't see the display.

You can't help but think these animals have developed a way to sense through the murk,

there would be no reason for us to know how to do that, we don't live in a situation

where the farthest thing we can see is 15 inches away from us - they do.

If you can see anything down there at all, then that camera's a miracle.

It's a miracle.

The team are in sombre mood.

No-one suspected the visibility to be quite so terrible.

The whole future of the expedition is in doubt.

But there's no giving up.

First thing next morning, the boats push further up the river

and into the unknown in search of better sites.

The diving will be dangerous. The job of keeping everyone safe rests

with dive marshal Richard Bull.

In all the hair-raising deep adventurous diving I've done,

this is some of the most challenging I've ever come across.

We have great expectations piled on our heads to deliver unique images, OK - well, I'll buy, I'll take that

challenge on, but what it means is we've got to go to different places and dive and dive and dive.

Powerful lights and high definition cameras are being used to cut through the murky Amazon waters.

But high-tech gear brings no protection from predators.

Mike Pitts has spent his career filming the creatures of the deep.

I think if you can see something from a distance, you don't think half as much about it, it's when you have

that very limited visibility and they're on you before you

could even do anything about it, it's like you can see a tiger shark

from 30 metres away and you're happy, you're fine, you can face it off, but in this low-vis, it is a worry.

Professional divers train to stay calm in the face of danger and keep their fear firmly under control.

I'm not going in the water feeling 100% happy, but once you have a camera in your hand, you're checking

your focus, you're checking the lighting, you're communicating

with your buddy, if you let yourself start thinking about it too much, you'll always be looking over your

shoulder behind you and I'm sure we are gonna get moments where we get bumped by things down there.

-But people who have spent their life by the river are not so relaxed about the dangers.

-I have to

be sure that nobody gonna be hurt by anything

and I know that's my...my job is to protect all the crew.

I spent all my life fishing, I've been in contact with the

stingrays and snakes and electric eels - I mean, they're really bad.

Every year, local people are attacked and killed by underwater predators.

The divers are not immune.

The teeth of the red-bellied piranha are razor sharp and can easily slice through a wet suit.

The electric eel will discharge 600 volts if disturbed, leaving a diver unconscious.

But for the people of the Amazon, there is

another creature feared even more -

it lives in the depths of the river and has never been filmed...

The giant jau.

The jau will not come to swallow men,

but maybe if they're in a school of fish, try to grab something -

maybe they get scared and, hit someone with their head, and, or swallow leg, pull you down

and this will be dangerous for sure.

They, they bite, you know, they don't have sharp teeth but they have

a big mouth - you know, when they're very big, they can swallow anything.

Three friends of mine they jump and they then decide to go swimming to the shore

and one of them disappeared so, we never found his body, never.

The giant jau has a terrible reputation for dragging fishermen down into the depths, drowning them.

Reports have come in to the expedition team that jau have been found further up river.

We heard from the village cos we've got some contact with this village,

that they caught two jau catfish there, about a week and a half ago, so we

-should see a big fish.

-Can we expect to actually find one under a ledge and we can get relatively close and

-he's not gonna leave?

-I think so, yeah, they'll, they'll be very still, I think they'll be just...

It's a unique opportunity to film one of the Amazon's most infamous animals.

You know about all these dangerous creatures and the jau is one of them,

you know about anacondas, you know about caiman, you know about piranhas,

but the reality is that none of us have actually seen what they can do,

you know, we haven't experienced it so...

In a funny sort of way, you actually feel a little bit, oh,

it'll be fine, because the reality hasn't hit.

Kate sets off upstream to check out the information.

As well as being part of the dive team, over the next month, Kate

has the added task of tracking down the wildlife on the river margins.

Oh, this is just extraordinary.

A family of capybaras on the bank,

this huge Amazonian rodent. It looks like four young...

Oh, I just know I'm not gonna want to go back to the boats.

Think I might run away and stay here.

But she can't stop for long -

she needs to find the fishermen that have seen the jau.

Back downstream, the countdown has started for the dive team.

-Oxygen supply pressure OK.

-Yes.

Other supply pressure OK.

-Yes.

-Computer electronics turned on.

Yes.

-Absorbent time remaining OK.

-Yes.

-Gas flow direction OK.

-Fine.

-Oxygen turned on.

-O2 on.

-Computer turned on.

-Fine.

-Batteries OK.

-Fine.

The pressure is on.

They must find and film the creatures concealed by the river's turbid waters.

Thirty miles upstream, Kate has had a stroke of luck -

she's found a fisherman who's seen jau.

Quantos kilos...?

Mike topside, Mike topside.

Thank you.

In the murk, the divers can't find jau.

In fact, they're struggling to find anything.

But then, something extraordinary.

Gradually, in the gloom, a giant colony of sponges appears before their eyes.

Holy cow, well, I'm just gonna shoot it.

Normally, these primitive creatures are only ever found in the oceans.

Looking closer, the divers slowly begin to

make out camouflaged creatures, motionless amongst the sponges.

This prehistoric species wears an armour of sharpened scales as a protection from predators.

Even their fins hide switchblade spines.

The river reveals an abundance of catfish perfectly adapted to feel

their way through the darkness with their gigantic whiskers.

Stay on the catfish, stay on the catfish.

Oh, he's gone.

A whole community of exotic fish are hidden here.

And then almost buried from sight -

the king of the river bed...

The giant freshwater stingray,

its barbed tail laced with enough poison to cripple a diver.

Extreme stuff.

A tantalising glimpse before it disappears into the gloom.

The divers have been in the water for three hours now, and air is running low.

Suddenly, a little freshwater sponge appears - next to it is a little fish, couldn't get a shot of it,

thought, "Yeah, that that was interesting, let's keep looking", so we came, kept going up the slope,

more and more sponges, more and more fish and finally we settled in to a big bed...

It's the first time this unique habitat has been captured on camera.

It's weird - what are they doing here?

You keep reminding yourself that you're in freshwater by tasting it,

otherwise it looks like you're in the ocean when you see that stuff, they're not supposed

to be in rivers, everybody knows that. That was pretty spectacular, that was a good fun dive.

-There is a sense of relief on the dive boat.

-Saluje.

Saluje.

-Big success.

-At last they're starting to find creatures.

But they all know there are many more spectacular creatures to be discovered.

First thing next morning, Kate passes on her news.

I've got a treat for you - I've got reports of jau,

the big catfish, I met a fisherman up there who caught one - 36 kilos - and he is pretty sure there's another

one up there because he was descaling a fish in a boat in the middle of the channel and this thing came over.

And took it.

Together they start on the journey back up river to the dive site Kate's found.

Now, look over there, Mike.

Wow, that's beautiful.

It may be below that waterfall, lurks our goal...

Jau.

Spectacular.

Comes out of nowhere, almost looks like one of those sort of slightly cheesy backdrops

you used to get in kind of '70s restaurants.

I'm just sitting here thinking, we're gonna go diving in that.

I know!

My gosh, look at that.

They are followed by the rest of the dive team,

and together they set about making camp on the beach.

The water here is fast flowing and strewn with boulders -

perfect conditions for jau and many other fish.

The local delicacy - red-bellied piranha.

Be underwater.

Don't need to be underwater.

Oh, you want to do under, OK.

The turbulence from the waterfall causes a scum of natural foam.

The foam blocks out the light and the divers drop into darkness.

The labyrinth of ledges and caves are a perfect hideout for jau.

That's better.

A pike cichlid is captured in the spotlight as it swims for cover.

In a crevice, catfish shelter

from hungry predators and keep a watchful eye on passing prey.

At last, a hint of the incredible life hidden in the river.

They discover one of the most peculiar creatures of the deep - knifefish.

These quirks of evolution navigate in the dark waters

by using a sixth sense - electrical pulses generated by highly adapted muscles.

They're so specialised they can even talk to each other with their electrical signals.

And hiding in a sunken log,

a prize. One of the largest knifefish in the world.

Called the black ghost, it is shy,

nocturnal and rare - and has never been filmed in the wild before.

Holy cow, that's just beautiful!

There is still no sign of the jau,

but in this maze of rocks and caverns, its secret lair could be just feet away.

Fortunately, the piranhas are keeping their distance,

and now with their air getting low,

the divers are forced to stop their search for jau.

We found a lot of fish down there,

and almost all of them hated the light and were tucked away

in nasty little rock or wood crevices,

so you couldn't get a clear shot of them but yeah, we did what we could.

It's been really nice after my first dive yesterday in that thick soup,

to come here and see something living in the river, that was good.

Try as they might, the team could not track down the jau.

After two days of searching, they are behind schedule, and must move on.

A decision is made to split into two teams.

In the first, Mike joins Brazilian professor Mario de Pinna

on a mission to find creatures never filmed before.

-Fish that talk.

-FISH CROAKS

Animals that hunt using electricity.

But their ultimate goal...

to discover species completely new to science.

In the second team, Kate Humble heads deep into the jungle.

Her mission - to track down two of the Amazon's most elusive animals,

the rare giant otter

and a strange pink river dolphin - the boto.

On their quest for new species, Mike and Mario have to cross

one of the world's great natural spectacles -

The Meeting of the Waters.

Here the black waters of the Rio Negro

join the milky waters of the River Amazon.

Now how long will this very, very definite line of demarcation last?

It takes several kilometres,

-cos the two water types are so different...

-Wow.

..that they actually will not mix for quite some time.

There we are, getting close.

Look at that! Astonishing!

Well, we're now leaving one river...

entering another.

Leaving the Rio Negro, they enter the silt-laden Amazon.

Rich in minerals swept from the Andes,

this river contains more types of freshwater fish

than anywhere else on Earth.

An ideal hunting ground for new species.

Many people make a living from the river,

but all are wary of the creatures lurking in these murky waters.

Mike is searching for one of the most feared of all.

It's just five centimetres long...

the candiru.

The candiru has... a nasty reputation,

a reputation nastier than pretty much any fish

I have ever met in my entire life.

Candiru are vampires,

parasites of other fish.

They enter their host's body through the gills

and gorge on their blood.

But in the turbid waters of the Amazon,

they sometimes enter humans by mistake.

There was the medical record of the guy

that had the unfortunate experience of a candiru swimming up his penis,

so now every thing I've been told not to do, we're about to do.

Go into the water with a little fish

that has a nasty habit of swimming up your urethra.

That's right, that's what you're about to do.

And you will notice very tight mesh.

The candiru is more common on this beach

than anywhere else in the Amazon.

But there's only one way to find them.

You have to get IN the water.

I think you will be safe.

-At least, I hope you will.

-All right, that's it.

I'm committed now.

BIRDS CAW

One hundred kilometres away, Kate's team is searching

for aquatic giants on one of the world's biggest reservoirs.

When it was dammed in 1987, it drowned half a million trees

creating a lake larger than Luxembourg.

It's extraordinary. I mean, it has a kind of ghostly beauty about it.

This area now, partly because it's so protected,

has become home not just to a huge diverse population of fish,

including the black piranha, which is the most fearsome of them all,

but also to turtles and to giant otters.

Very, very exciting.

But finding the otters in this vast area won't be easy -

less than 5,000 remain in the whole of South America.

After six hours of looking, Kate hasn't seen a trace of an otter.

But this remote reservoir has become home to a huge variety of wildlife.

It's incredible.

There is so much to look at.

Mike's team are having no more luck in their search for the candiru,

but they have netted a trawl of bizarre little aliens

whose ancestors originally came from the ocean 1,000 miles away.

Look at those teeth.

It's a needle fish.

I have a marine version of this that looks exactly like this actually.

Snappy little fella too. All right, all right.

This is everybody's favourite,

it's a puffer fish. When a predator takes him,

he puffs up and they can't get him down, so they let him go

or he can go into a crack and puff up

and he can't be extracted.

I need to get him back in the water pretty quickly though.

No sign of candiru yet, but instead a fish that wards off predators...

Check this guy out.

-..by talking.

-This is a doradid

Doradid.

-Armoured catfish.

-FISH CROAKS

It's a...makes these sounds trying to get rid of you.

Go ahead, bring it up. Here we go. Come on, say hi.

FISH CROAKS

-Be careful of...

-He's saying, "Please let me go."

All right, I'm letting this guy go.

See, ya. Well done, obrigado.

Kate's found another distraction on her search for giant otters.

A skimmer - plucking fish from the surface of the water.

BOTO HOOTS Ooh! Oh, my God!

I want to get in the water, we're absolutely surrounded by botos.

Boto, a pink freshwater dolphin...

Well, this six hour journey has now extended

to...I think about eight hours.

It's entirely my fault.

There's so much to look at.

-CREWMAN:

-We have to make camp before...

We have to make camp before it gets dark.

I must stop, we're here for two days. I'm sorry.

Desculpe. Vamos!

Right on the bottom...

Mike and his team have been in the water two hours.

If a candiru enters their body

they'd need emergency surgery to cut it out.

OK. There's one.

But at last he catches one, fortunately in the net.

These fish have modified teeth outside of their mouth,

so these are not real spines, they're actually teeth.

That's what all the fuss is about...

candiru, candiru - the famous or infamous.

Now when they're full of blood,

presumably this will be a little larger in diameter and red.

-Yeah, yeah, they go to about twice this size.

-Oh, I can feel those.

-Oh, you can feel the teeth, yeah?

-Spines...the teeth, yes.

So now you can see how it actually moves

when it's trying to get into something.

Buoyed up by their success, they move on to their ultimate goal -

to discover species completely new to science.

-They go in here, Ian.

->

The team are going to try a new tactic -

to dive in the dead of night.

They use the daylight for preparing their gear.

Underwater cameramen Mike Pitts makes his final equipment check.

Nine-tenths of any job underwater is done up here.

Simple - it? Well the simpler you make it up here,

it's so much easier when you're down there, but the camera system is ready to go.

It's time to test their theory.

-Absorbent time remaining, OK?

-Yeah.

OK. Computer electronics turned on?

-Yeah.

-Diluent analysed?

Oxygen turned on?

Yeah.

Diving at night is more dangerous.

It's all too easy to get lost in the darkness.

If anything goes wrong, they're totally on their own, the nearest hospital is three days away.

God, they're all in.

Leaks...weights... all sorts of things,

currents in different directions, but they're all in.

I'm getting happier by the minute and they're all going for it.

OK. Let's go.

This alien world may seem empty.

but in these depths, strange creatures do exist.

The blind tube-snout -

one metre long, but only a centimetre thick.

It uses pulses of electricity to communicate and find food in the gloom.

But when the fish come out...

so do the predators.

ECHOING CALL

Somewhere in the darkness, a boto dolphin is searching for prey with sonar.

Suddenly, there's a problem.

Mike Pitts' air supply has malfunctioned.

He's 20 metres below the surface

and in danger of losing consciousness.

-DIVER:

-Certainly will.

Despite the urgency, it's crucial they ascend slowly.

Coming up too fast can cause serious medical injuries,

including the bends.

Port stern!

Stand by, while I do a pan of the light.

We'll tell them we're on the bow and I'm going over to the top lines.

-DIVER:

-We'll be extra vigilant when we come up.

Both of their computers are yelping like crazy.

Pitts is out of the water still with a re-breather problem.

-Jesus.

-The guys are just over an hour into their dive and they had a re-breather problem.

I'm not entirely sure what it was,

it sounds like some electronics had gone down

and they'll have to fly them manually.

We've taken first aid precautions.

The last little bit of their ascent

was quite rapid, right?

And it's that last little bit that is important.

We've put them on pure oxygen as a precaution.

I half considered dropping the camera -

-half considered it.

-Oh, that's pretty serious.

Then I thought I can't control it properly with the camera,

so I better just drop it.

You feeling all right, fellas? Just give me a thumbs up.

The incident drives home just how alone they really are.

Next morning, Kate's been joined by Fernando Rosas

who has spent four years studying giant otters.

He knows that to have any chance of filming them,

they must start their search at dawn.

It's just gone five in the morning,

so we're feeling a little bit bleary eyed

and Fernando and I are on a quest

to see if the giant otters are having more of a lie-in than us.

Fernando often goes days without seeing an otter

and he's developed some unconventional techniques

to find them.

Yeh, yeh, yeh, yeh, yeh, yeh, yeh!

Yeh, yeh, yeh, yeh! Phroo, phroo...

That's obviously good morning in otter language.

And this is the den, you see, underneath the vegetation.

-Under, yes.

-The entrance of the den here and there.

I'm also collecting some faeces

to know what they are eating here in the lake,

because we know giant otters, they eat mainly fish like piranhas.

And what sort of piranhas are in this lake?

Mainly black piranhas - the big ones.

Yeah, they can reach up to two kilos, they are big, big animals.

-And very aggressive.

-They are very aggressive.

This lake is teeming with black piranhas.

It should be perfect otter territory.

Mike and Mario are still on the search for new species.

It's going to take them to places far too shallow for the main boat.

The Amazon's small streams are crystal clear

because it hasn't rained for weeks.

This might be their best chance to find new life.

Drag your fingers through the sand.

But nothing's that simple in the Amazon.

THUNDER CRASHES

It makes me wonder how stupid we are

standing in water while that kind of activity is going on.

This rain is going to wash down this exposed clay and mud

and it's going to turn to muck.

It seems their best hope of finding animals new to science

is being washed away in the mud.

Finally, we find a place where we think we can work

and this is what happens. That's typical, isn't it?

My God, look at what's happening the other side.

Back at the reservoir, the sun is shining on Kate and Fernando,

but that means the otters may have left their dens for the day.

The opportunity to film them may already have been lost.

They are there. They are leaving the den.

Yes, look! Look - up on the bank.

-Up on the bank.

-That's right.

Was that call a warning call

-or is it a sort of...?

-Just kind of alert...

They are relaxed, they are not alarmed, they are not in danger, they know us.

It's just like a little constant chuntering going on. Chick, chick, chick.

This one's got a fish there -

a big fish.

Just getting a better grip.

They cover so much ground so quickly

-And they swim very fast.

-Very fast.

Hunted for years for their fur, they were nearly driven to extinction.

Here, at least, they are safe.

-From the front, when you can't see the tail, they look amazingly like sea lions.

-Yeah.

Tiny little ears...

Because the feet are totally webbed they could almost be flippers.

-(So they can swim, yeah?)

-(Yeah.)

So do you think this might be the alpha male and female?

-Those two here?

-I guess so.

I can see why you come back...

..year after year after year. They're just...magnificent.

I just don't see this working.

Mike's having no luck at all.

The rain has spoilt his chances of filming anything.

-No, this is going to be muddy

-for the rest of the day.

Hey, Mario!

This just isn't gonna work. I can't see anything. I think we catch them, put them in the aquarium.

Please!

Filming animals in ankle-deep mud is impossible.

Mike and biologist Mario

decide to catch and film fish in a tank instead.

Oh! Oh! Look at that.

Here we have several representatives of the...

-This is a...

-That's a catfish...

I can't believe this, just one...

-One.

-Is this common here - just one scoop and you get a dozen fish?

Yeah, yeah. There's a lot of life,

it's amazing how little water can hold so much life, it's fantastic.

-Amazing.

-In the net, Mario spots something that looks different.

If we can put them temporarily in a tank then if we...

Yes, well we have been...

These people live beside a small stream

that has as many types of fish as all the rivers in Britain combined.

The team set up a portable jungle studio to film the unusual fish.

Tiny fish is where the great things to be discovered are.

That's lovely.

-PITTS: It's really small.

-Right in front of the tripod.

It looks like just a tiny little white one. That's what we need.

OK. Well!

At last, they've found what they've been looking for...a new species.

This is perfect, this is ichthyological history.

Just fantastic.

Hold that there.

That's a great view of its stomach.

-Boy, that is no doubt that that's blood.

-Yes.

This is a new species of something really weird that sucks blood.

In addition to all of that, it has become really small,

so it can actually use the fish in these little creeks.

It's a new species of blood-sucking catfish.

It may be small, but it's an important scientific discovery.

No doubt this is blood...

Animal vampires often possess chemicals

that thin the blood of their victims.

It's possible their discovery

could lead to better treatments for heart disease.

-Well done, Mario!

-Yeah.

-Bungling amateurs.

After Kate's success with the otters,

she's determined to find the boto dolphins.

She's had a tip-off.

It seems the best place to find wild boto is the local beach resort.

This small town has become quite famous for this little restaurant,

which is just over here,

because the daughters of the owners of this restaurant

have been feeding the dolphins and it may be that not only can I feed them,

but I can get into the water with them.

Kate lures the boto in,

so that the sound recordist can try to make a rare underwater recording

of their calls.

BOTOS CLICK

RECORDING PLAYS BOTOS CLICKING

Even though they're coming right up here...

..you still, can't really get an idea of what they look like

because it's so dark down there.

I want to see your face.

SHE LAUGHS

There's one right here.

Unbelievable.

Extraordinary beaks - they've got long rows of teeth on either side.

Totally twisted beak...

Oh, there's a big one here.

Got these really big, kind of, bulging foreheads,

which is the sonar.

Which they definitely need in water this dark.

A constant clicking, clicking.

Is there any...? Have you noticed like

when they come up and take fish does the sound change or...?

It's like, when they're coming in they start...

Now that Kate's attracted the botos,

the camera team can get in the water.

But they've no idea how these dolphins will react.

Woh!

The dolphins show no fear of the cameraman

as they swim through their strange world,

stained deep red from the rainforest's leaves.

They like your bit better.

This is fantastic!

Kate's team are achieving their goal

by capturing remarkable underwater images of these amazing animals.

They're also discovering that wild botos can be surprisingly gentle.

There's this, um...

There are various stories,

legends about boto - that they take human form

and whisk away the prettiest girls in the village

and it's very strange, looking at them underwater

they do look curiously human

because their skin is the same colour as ours

and, you know, they have this sort of quite human looking form underwater.

BOTOS CLICK

Well, I think...

they are officially full.

There's one down here tickling my feet.

Oh, there you are! Do you want it?

That's it, no more fish.

What an amazing...

amazing experience.

Kate heads back to the ships, and together they travel upstream

to their next destination.

With all the experience they've gained, their next challenge

is to dive the very deepest part of the Amazon.

Hidden in the water is an abyss - a 90m-deep channel

gauged into the river bed. Scientists have no idea what lies in its depths.

I feel very comfortable we will see something we have not seen before.

I really strongly feel that. We will be far deeper than we've been before,

and I'm really excited about what we're doing right now.

The expedition is about to start its second phase.

The team plan to take cameras into this abyss to find and film

the creatures that hide there.

The three Amazon riverboats head off once more along the mightiest river in the world.

The abyss they are seeking is 1,000 miles from the sea

and they will have to journey through the night to reach it.

But nothing goes to plan in the Amazon.

CRASH!

They've struck bottom. The boat has juddered to a halt.

The shaft is bent? Struts, flapping?

The problem is the strut is bolted into the hull. You knock it to the side, it pulls a piece of wood,

a hole in the hull!

Mike Pitts volunteers to inspect the damage.

We've taken on water through this. If that starts with a vengeance,

voom! Down it'll go.

The momentum of a 60-ton vessel going over a rock,

-it will open it up like a can of sardines.

-Not good.

The boat is taking on water and the propeller is bent.

In the darkness, two divers grope their way on the bottom of the hull,

hoping to find the full extent of the damage.

-'It's surface.'

-Pretty gloomy!

They're marooned on a sandbank in the middle of the Amazon.

The expedition has juddered to a halt.