Episode 7 Amazon Abyss

An expedition is exploring one of the last frontiers on Earth.

Penetrating the depths of the Amazon River,

they've already found some extraordinary creatures.

Knifefish that communicate with electricity.

Blind freshwater dolphins.

And they've discovered a new species of blood-sucking catfish,

never seen by scientists before.

This is perfect. This is ecotheological history.

But heading upstream into the deepest jungle, they hit a problem.

CRASHING

Their boat struck ground.

That's not good. It sounded to me like either a shaft is bent

or there's struts flapping around.

The thing is, we're taking on water through the stern.

The whole expedition is on the rocks.

The team's lead boat has limped back to port.

It's not easy to find spares in the Amazon

and it's taken two days to repair the hull and propeller.

Now they're behind schedule.

In this phase of the expedition,

the team's task is to explore the deepest parts of the Amazon.

Hidden under the water, there are some deep channels gouged into the river bed.

Scientists have no idea what lies in their depths.

But to dive them, first they have to find them.

I feel very comfortable that we are going to see something we have not seen before.

I really, strongly feel that.

We're going far deeper than we've been before.

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

A trench has been located.

There are deeper ones,

but this is still big enough to hide the Statue of Liberty.

No-one has ever been to the bottom.

The currents here are fast and unpredictable.

It will take good seamanship to secure the boat safely.

The divers must compose their minds before they enter the water.

For Mike and his dive partner Florian Graner,

it will be all too easy to get lost or swept away by the current.

They will be diving deeper into the Amazon than anyone has ever been.

The river is a soup of stirred-up sediment.

The deeper they drop,

the worse it gets.

The surface crew monitor every word and a safety diver waits on standby.

Visibility's so bad that he's having to hold on to Florian.

At the bottom of the hole, the divers sink to their waists in thick, clinging mud.

They decide to abort the dive and send a surface marker to guide them up.

They have the most advanced camera in the world...

but all they have filmed...

is mud.

Once you hit the bottom, you can hardly feel hitting the bottom, then, whooom, this cloud came up.

It is complete blackness, mud, not...I mean the particles...

that's why I said, "Let's see what this is."

It was big particles of gunk, just...

No-one had expected visibility to be this bad.

There's going to be no way to film deep water creatures in this stretch of the river.

For now, there's a change of plan.

They travel upstream in search of water that's shallower and clearer.

And that means venturing into the very heart of the rainforest.

We get into the kind of Amazon of the imagination.

The great dripping forest, maybe a narrower river.

This idea of going up into

what we all affectionately call the Heart of Darkness

is something that I've been looking forward to for the entire trip.

There's a labyrinth of lakes and forest streams

that feed the main river.

In the Amazon,

the strangest creatures swim through the trees of the deepest jungle.

The next afternoon, the expedition is surrounded by virgin forest.

They decide to split into two teams.

Cameraman Mike de Gruy and naturalist Kate Humble

will be looking for clear-water jungle streams.

Hasta la vista. Let's go.

Our plan is to go up river about an hour

and find another little stream which comes out and explore another lake

which has different fish, including, we hope, electric eels.

Of the thousands of species that live in the jungle waters,

the electric eel is king.

They hunt with 600-volt electric shocks

and use the same weapon for defence.

This fish breathes air.

Uniquely adapted to the oxygen-poor waters of the Amazon,

the lining of their mouth acts as a lung.

I need a pick-me-up before I go out there.

Second team leader Mike Pitts sets himself up for the day.

Brazilian coffee.

He's going to a jungle lake to film rare fish.

But it's also rumoured to have a large crocodile - a caiman.

One with a grudge against people.

Somebody shot at it

and it's got either an eye missing or it's got a crease above its eye.

It's been hit by one of the fisherman or locals,

they were worried about it,

which I think is a bit unfair.

Do you think that will make it more nervous?

It might have an attitude.

It might have an attitude problem!

Are you going to accompany us on this one, mate?

No, thanks, I've got work to do!

He's more sensible than that!

Nearby, Mike and Kate are looking for a stream with clear water.

Well, we wanted overhanging forest, didn't we?

Yeah.

We can go in and snorkel first.

-OK, well, why don't you get in?

-See what it looks like.

Mike finds a world of tangled roots and poor visibility.

These are a lot of the same fish that we saw.

Yeah.

I'm going to go and look in the trees.

Every stream and river is different and they never know what to expect.

How is it?

Very muddy.

I don't see anything that we haven't seen before.

They'll have to try somewhere else.

Mike Pitt's team carry their equipment through the jungle

to the lake with the one-eyed caiman.

There are two local guides on the expedition,

Eduardo Gomes and Samuel Basilio.

They believe the lake is their best chance to find unusual fish.

My pants have fallen down!

We checked before, me and Eduardo,

and there is a big caiman over there.

I just heard another story about a snake here -

the anaconda - but you never know.

There are a lot of stories about it.

We just want to be sure that nothing can happen to our divers.

Three days ago the guide saw some of them at the end of the lake.

-The anaconda?

-The anaconda.

It wasn't that big. About six metres - about 18 feet long.

-So...

-Big enough for me.

-Yeah.

The team's filming permit doesn't allow them to carry a rifle.

They have to rely on Eduardo's bow and arrow

in case the caiman strikes.

On their way back to the boats, Mike and Kate take a short cut -

or so they think.

Fallen trees are a common obstacle for locals

but for strangers it's a bit of a puzzle.

Kate, I gave you a Swiss army knife.

If you've brought it, could you please cut that log out of the way?

Well, let's think.

Is there any way round this?

-We could lift that over.

-Yeah, we'll have to...

What about if we can pass people over the tree and into the boat?

Mike, help! What's going on?

You want to lay it down?

It won't leak? How do you say leak?

I just don't want gasoline in my boat. We're going to go over.

Here.

I see what's he's saying. I like his idea. It's going in the water.

I think that is a great idea.

You got it?

-There's more than one way to skin a cat.

-I've got it!

Come on! Just make a decision!

I got it! I got it. There we go.

There, that was easy!

Mike Pitts' team enter the lake

rumoured to have the one-eyed caiman.

It's a big lake.

Yeah, there's a lot of places for the alligator to hide.

Eduardo makes baby caiman distress calls.

If adults are here, they'll show themselves.

I'm sure you guys are right. There's gonna be stuff in here.

Local children gather to watch the oddly dressed strangers.

The circus has come to the jungle.

Yeah, we got it. I got it, I got it.

A school of angelfish drift by in this underwater jungle.

Most tropical fish kept in captivity come from the Amazon.

Everybody watching them and the little boys are saying

they don't know how these divers can swim with their big shoes

and they can't believe they can swim so fast

and go under the trees like that.

It's a big entertainment for them.

Meanwhile, the edge of the lake is being searched

by diver and cameraman Florian Graner.

Well, here we have a whole group of little caimans.

He must approach very slowly.

If these babies make an alarm call, the parents may come.

We are wondering where the mum and dad are, really.

(Where's Mama?)

(Where's the adults?)

There's still no sign of Mother.

And the babies are getting very relaxed.

They're becoming quite sociable.

-What's he doing?

-HE LAUGHS

That's just unbelievable!

Those caimans have just come up right to the camera and to me!

I didn't have to go to them, for a change!

In the middle of the lake,

Mike Pitts finds a school of silvery Amazon brycons.

They glide past searching for fruit fallen from the trees overhead.

Many fish here have developed unique behaviour.

Mike discovers something remarkable.

Two cichlid parents are protecting their fry from all comers,

including cameramen.

They've dug a deep hole in the sand with their mouths

to make an underwater nursery for their babies.

Beautiful fish! Beautiful.

At night it will be a whole totally different game I think

because once that sun drops down

I'm sure it's going to change a lot.

So I think we should be here.

I just talked to these guys here. They said be careful

because at night everything comes out and there are caiman and snakes.

But it's not only caiman that come out at night.

The boats have beached for the evening.

And as the crew relax, all around them is the distinctive sound

of hundreds and hundreds of bats.

There's over 100 species in the Amazon,

including the infamous vampire bat.

They roost in hollow jungle trees.

By night they fly the forest feeding on monkeys and other mammals.

To find out if there are vampires around,

Kate puts up one of the expedition's nets in the jungle.

I'm just setting up this very, very fine net -

a mist net -

which will trap any bat flying in this direction.

This will allow us to actually get a good look at one

without it being harmed.

Right, I think that's ready. Let's turn the lights off and wait.

Mike Pitts' team are ready to dive.

They're hoping the night will reveal fish that can't be seen by day.

Samuel and Eduardo keep an eye out for the one-eyed caiman.

If we see caiman coming our way,

I suppose we all cross our legs, hope for the best and keep filming.

I think we'll get some stuff so let's go for it.

In this tangled watery forest, the divers risk getting stuck.

And every log could hide the caiman.

But it's worth the risk as they capture behaviour never seen before.

A transparent sandknife fish

burrowing through the sediment to escape predators.

And a striped gar propels itself with the tiniest fin movements.

Suddenly Samuel confronts something in the water.

It's a caiman, but certainly not the giant they were worried about.

This is a red caiman.

They don't grow big - one and a half metres maximum -

but it's one of the species that are very deep in the forest

and it's very aggressive.

See?

If you put it here, it will jump on your leg and bite!

CAIMAN SNARLS

While Samuel releases the red caiman,

the team steal an opportunity to film it.

We've been waiting about 20 minutes...

to see if there is anything.

Back in the jungle, Kate checks her bat trap.

OK.

What's that?

Ah-ha!

Look at this.

OK, now this is unmistakably...

..a vampire bat.

Isn't it funny that a creature as small as this

should inspire so much fear?

Pointed ears and this sort of double nose.

Very elongated canine teeth.

That's what does the damage.

Right, I think we should let him go

and hope to heavens he doesn't double back and bite me for revenge.

Off he goes.

Next morning, as they head up river, they find a huge caiman

with just one eye.

It wasn't a rumour after all.

It had moved out of the lake and into the main river.

Perhaps it was more afraid of the divers than they were of it.

They've filmed a wide variety of fish in remote jungle lakes

but there's one creature they haven't seen -

an electric eel.

The expedition decide to fan out to find eel streams deep in the forest.

Let's go!

Mike Pitts' team will be searching an isolated jungle stream.

With no boat access,

they're forced to carry their dive gear through the sweltering forest.

Kate and Samuel take the chance to search the surrounding jungle.

There's something about a tree this size

that kind of renders me speechless.

-Yeah.

-It makes me feel very, very small and very insignificant.

Now look at this, Samuel!

That's extraordinary!

That's the most enormous ant!

Be careful, that's very poisonous.

-Now what would these ants normally prey on?

-The other insects.

Other insects.

Now you can feel - the smell.

-Oh, yes, it's a really strong acidy smell.

-Acid.

When it stings, it's painful for about 12 hours.

If you're allergic, it's able to kill you.

So it can be like a wasp sting.

-Er, stronger.

-Like a scorpion?

Six or ten times - like a scorpion.

It's looking for something to bite and sting.

But electric eels do more than sting.

One zap can knock a diver unconscious.

I've been told you're down there

with a hand grenade with a pin pulled out

and just thinking, "That's gonna go off any second if I get too close."

I've been told that if you get closer than a metre,

it may well give you a really severe shock and it's gonna hurt.

Despite reports that this stream contains eels,

they're having trouble finding them.

Mike is confronted by an angry pike cichlid

defending its adolescent young below.

Pike cichlids are a bit like humans in their parenting skills,

staying together to protect and even feed their family

until they're nearly fully grown.

They have the longest parental care of any fish in the world.

We've had a look in this pool and there's no sign of any eels at all

and unfortunately we've lost the light.

But we'll come back. We'll come back.

But it's a marvellous location, it really is.

We could spend a week here, couldn't we?

It's full of spiders, scorpions.

There is also a lot of snakes.

The rainforest is full of animals that protect themselves with poisons...even caterpillars.

Very strong, don't touch it...

It burn and hurt a lot.

It hurt for like two to three hours.

It looks toxic.

Incredible piece of design though, isn't it?

They press further into the forest.

And in a hole in the ground, a creature lurks.

Very, very different kind of spiders...

here it comes.

Oh!

The giant white-kneed tarantula.

So this spider would be trapping what?

Small mammals, birds, insects.

-Is it poisonous?

-Yes.

-By using a noose made from grass, Samuel can lasso the spider.

He must take care.

This tarantula defends itself

by flicking stinging hairs through the air at any potential foe.

Incredible jaws.

-Isn't that amazing?

-It is.

I've never seen this kind before.

In the Amazon, new animals are waiting to be discovered all the time.

Taking the whole forest down!

-What is this?

-Well, this is the water vine. I'm just thirsty.

We've walked for miles and miles

and this is really good water. Drinkable water.

Here.

That is amazing water though. You could bottle that and sell it for...

£3 a bottle.

Oh, this is not a good one.

I thought it was fine! What's wrong with it?

Did you want it to taste like beer?

Isn't that extraordinary though?

Next morning, the whole team join forces for one last big push

to try and find the elusive electric eels.

They think this overgrown stream is their best bet.

This looks great.

Obviously these are one of the kings of the Amazon River

and they can kick out a 600-volt wallop when they're threatened

or when they want to kill something to eat.

Anybody comes along they don't want around - kapow!

And that pretty much does it.

But before they can get started, the heavens open.

THUNDER RUMBLES

The rainy season is due to start any day now.

If the rain continues, it will muddy the water,

and it will be impossible to find anything in the river.

Can you look after my nice dry towel? Thank you.

But as quickly as the rain started, it stops.

Kate gets into position to try to spot an eel.

They need to come to the surface to breathe every 15 minutes.

Eduardo tries to attract one by mimicking a fish in distress.

What's that? There's the eel! Just there! There's the eel! There he is!

He's just there! Everybody stay still!

The eel's on the move.

-Eels!

-Bloody hell. Just get the...

-Mike!

-..camera on!

At first it seems they've missed their chance.

The eel's disappeared.

Everybody watches for the moment when the eel must come up for air.

Finally, they begin to capture an electric eel on camera.

The divers edge closer and closer.

If they move too suddenly, they risk being electrocuted.

The divers are now just inches away.

Yet the eel tolerates their presence.

Two? Yahoo!

That's good!

It's the most amazing thing. You see it rippling along there

and all the time I'm waiting for that 600 volts to go through me!

And could you hear anything? Could you hear any sort of clicking or...?

No, I couldn't hear a thing.

I am partially waterlogged in my left ear

but I couldn't hear a thing.

That was really good.

They got very close. That was really dangerous. Very close.

THUNDER RUMBLES

It's the final week of the expedition.

The first thunder storms of the rainy season have arrived.

But there's one more task.

The expedition is now heading towards its ultimate challenge.

Legend has it that in the centre of the Amazon,

there's an underwater trench more than 90 metres deep.

I'm entering this with a slight amount of trepidation.

No-one knows what creatures live there.

You can't help but to go into it... carefully!

Their aim is to take cameras into this chasm

to search for signs of life.

They'll be the first people ever to explore the Abyss.

Now, one thousand miles from the sea,

they are nearing the deepest point of the Amazon.

To help them film at these punishing depths,

the expedition has just taken delivery of a very special piece of kit.

-Yes!

-For Mike, it means they have a real chance of success.

-Fantastic.

-You're kidding.

Look at this!

This is an ROV - a remotely operated vehicle.

With it, they hope to make scientific history.

This goes way deeper than any of us can go.

We can take this, place it in a spot,

it can stay down 24 hours a day as an eye in the river.

We've got cameras, we've got a sonar, we've got lots of instrumentation that we can put on and take off.

This is a very cool toy. I mean, to be able to get a view

of the river that we would never be able to get as divers is great.

The other thing is that it doesn't run out of air, it can be down there all day.

They want to fly the ROV far beyond safe diving range.

Yep. You've got camera A.

To help, they're joined by Steve Sargison - specialist ROV pilot.

He's spent his career salvaging wrecks.

It's forwards, backwards, go left, go right.

That will give us full power and that will give us full power up and down, and this is a fine trim.

The river current runs at three knots.

The ROV will only just be able to cope.

The river bed here plunges to more than 90 metres deep.

This is the moment scientist Doctor Mario de Pinna has dreamt of for years.

We are here taking the opportunity of coming to these remote places,

but really the new stuff, the extraordinary stuff, is gonna be in deep waters.

Yeah, we'll turn it to the right.

Yes. Rotate to the right a bit.

-The ROV's first flight reveals a problem.

-Just pull it back...

One of the motors has failed.

Without full power the ROV cannot descend.

OK, it's hooked.

Unless the engine can be fixed, the Abyss will remain tantalisingly out of reach.

The robot is operating at its limits in a river so deep

it's a major shipping channel right into the heart of the jungle.

Steve needs to get to grips with the ROV.

Time is now precious.

The team grab a last chance to explore places that will soon be washed out by the rains.

Mike Pitts is going to look for fish on the forest floor.

Soon I'll need that camera.

Further down river, Kate and Mike investigate an area of jungle that is underwater.

Now the way this is gonna work, is I'll lay down and you drive my feet,

and that way I don't have to check.

All right, hold it, let go. I'll kick and see what happens.

To get steady images of this drowned jungle, Mike improvises a novel form of propulsion.

Every year vast areas of the forest are flooded.

The trees and wildlife are perfectly adapted to survive the inundation.

Fresh water sponges cluster in the branches, waiting to be immersed.

And fish spill out across the forest floor.

Mike Pitts is looking for fish that will be high and dry until the floods arrive.

This jungle has been above water for 3 months, Mike's team is joined by

a local scientist who's recently discovered unique fish on the forest floor.

Right, this looks brilliant.

Any fish here were trapped in pools by the retreating river

and must endure months in stagnant water before the flood returns.

-Maybe I think you must...

-Some so small they can only be found with a fine meshed net.

What did you get on there?

-It is a wolf characin. It bites.

-It bites?

-It's a small predator.

-Is that a fully grown specimen?

-No, it's a juvenile.

-A juvenile?

It will grow up to half a metre long.

-Half a metre?

-Yes.

-And it bites?

-Painfully.

-I'm going to release that, there we go. Put him back in.

But weather permitting, they hope to find an even more remarkable fish.

Big one.

On the journey up here Jansen has been explaining to me about the small catfish

which is probably blind, but lives in this very, very shallow water, or even in the soil.

It looks like a worm but it's actually

a fish. It's got feelers, the whole thing, but it's very, very small.

Big one, yep.

What's this here? Oh, nothing. Oh, no.

Yes, that's a fish. Look at that.

He's pretty red.

That is it, that's the worm.

-Or the catfish.

-It's a large one.

-That's a large one?

-Yeah.

If I'd found that by myself, I'd have said that was a worm.

There's no way I would have said it was a catfish. It has no name.

No name. It's a new species.

-A new species.

-Undescribed.

Undescribed and I've got it in my hand.

The whole of its body can absorb oxygen from the air -

a miniature catfish that can live on land.

It has taken all day to fix the robot and they are well behind schedule.

As night falls, they launch a deep water test dive.

This is the first ever attempt to reach the Abyss.

Ready?

But there's trouble brewing.

It can become a hazardous situation for the equipment so I hope the storm won't come,

but if we stop doing things just because of threats

of storms we'll never do anything here because there is a storm threat in the horizon every ten minutes.

Suddenly the storm changes direction.

This is weather that can sink ships.

Three metres...

2.5.

Until they get the ROV back on board they're stuck directly in its path.

The difficulty we have is that the ship will spin on its anchor, we'll get all wrapped around

with the ROV umbilical and that's when things get a bit nervous.

It seems the Amazon is conspiring against their mission.

So much electricity going on up there it's pretty impressive, and you can see

a different kind of splendour in the Amazon.

THUNDER BOOMS

Next morning, there's a break in the weather.

The robot is launched and descends into the unexplored depths.

150 feet.

At last they are poised to find out if there is anything living in the Abyss.

They're using a bag of fish bait to attract predators from the gloom.

Scientists know the Amazon is rich with life to a depth of 30 metres,

but the ROV is well below that.

We're entering around the realm of as deep as we've dived.

We got to what? 44?

-Yeah.

-Oh, hang on! We've got a fish coming in.

Feisty little fella!

-Straight in there.

-Six minutes, we have our first fish.

-There's two of them.

-Two now.

They've got tiny, tiny, tiny eyes and a big sucker mouth, they look like hag fish.

Probably vestigial eyes.

The bait is working.

Enthusiastic.

The first sign of life deep in the Amazon.

Brilliant.

There's five of them.

It's getting kind of busy. Look at that. Ah.

For Mario, a major breakthrough.

These are scavenging catfish, voracious candiru-acu.

We have never seen this spectacle before.

This is the first time I see it. This is wonderful.

They have huge muscles. The jaw muscles are so big

that they cover the whole head,

all the way to the mid line and that's a very, very powerful bite.

These guys can use a little hole to get inside and eat

the prey from the inside out, that kind of scares me more than I just have a piece of flesh taken away.

These scavengers feed on the dead, but can attack the living.

With a ring of teeth like a ripping circular saw, candiru-acu bore into flesh.

Fish thriving at 44 metres. But does anything exist in the deepest Abyss?

They may yet be thwarted.

The ROV has badly malfunctioned. Steve is forced to do electrical surgery.

It's going to take some time.

Next morning, with the further delay

and just two days of expedition time left,

Mike grabs a chance to fulfil a personal ambition.

His search takes him far into the jungle with Amazon guide Samuel.

They're looking for a sloth.

It's hard to find them because they crawl in the tree and stay there.

They don't move much. It's just like a ball.

If only we can find one of these things cos I really want to see a sloth before I leave the Amazon.

The fact they move so slowly, they're covered with algae

and so well camouflaged makes them practically impossible to spot.

This is ideal habitat for sloth, but it will soon change out of all recognition.

In the coming months a deluge of rain will flood the jungle.

It can all happen without ever raining here.

If it rains up by the Andes or somewhere else and the river just lifts up anyway.

Every year...

Phew! That is a lot of water.

But the sloths will remain high in the canopy above the rising water.

It takes an experienced eye to spot one in its lofty retreat.

Right in front of us is a sloth.

I don't believe it.

Three toes. Very, very sharp.

Look at that face.

Oh, man! That's the greatest face!

I think more than anything else I just love the way they look and move.

I wonder if they make decisions at the same pace they climb.

See, and I don't know why I've had this obsession about seeing a sloth

while I'm here, but certainly the sloth's unique and I saw my sloth.

Mike has realised a lifelong ambition,

but the expedition's main objective is still to be achieved.

At last, the robot has been repaired.

Fresh bait is secured... and quality-tested!

They have only two nights left

and storms could shut them down at any time.

They must quickly launch into the Abyss again.

The robot is primed for its deepest dive yet.

It's descending smoothly, dropping down towards the river floor far below.

No camera has ever pryed this deep in the Amazon before.

This is in a river.

This is in the middle of the Rio Negro.

250 feet - unbelievable.

To increase the chance of attracting fish in the greatest depths, they have switched to a low light camera.

Now all they can do is wait.

For five hours, nothing.

Then suddenly from the darkness the ghostly images of candiru-acu appear.

This is the first time anyone sees images of fish at 85 metres down.

-Look.

-They're going bananas.

There is life in the Abyss after all.

The 65 metre trap.

Yeah, this is the same species.

Look at that, look at that!

-Oh, that's beauty.

-Who is that?

It's another catfish that's also, it's partly a scavenger although not to the same degree as the candiru.

I mean, did you know that candiru would be eating and feeding at 85 metres?

No, I didn't expect that life below 30 metres would be that rich.

-What's that?

-That's great.

A relative of the candiru-acu, but even larger and more voracious.

That did not look the same. Who was that?

-Is that a different candiru?

-Yes, that's a Cetopsis coecutiens -

its scientific name. That's really different.

-It looked like a shark.

-The little ones are gone.

It's a beautiful fish. It's silvery, it has a long dorsal fin.

And did you guys notice the difference...?

There it is. It comes, grabs a big chunk of flesh and swims away.

It doesn't stay like spinning around and trying to grab it.

They've revealed that the Abyss swarms with life.

Scavengers waiting for anything the river brings them.

It's amazing. It's really... These images are something really original.

It's the expedition's final day.

To get better pictures, the team decide to risk sending in the divers with their high tech cameras.

They are on the very edge of the Abyss.

There's a narrow shelf within diving range, but is it in candiru-acu territory?

No-one has gone face to face with these voracious scavengers before.

The divers are preparing for an encounter that could be dangerous.

If one bit you, you'd start bleeding quite profusely and that could attract the others.

Before you know, you've got a situation where you've got to get out quick.

So we're all wearing a 3mm suit, gloves, hoody and a mask on top, so we're all protected.

If the bait attracts candiru-acu,

once in the water there will be no going back.

Let's go.

ROV is now on the bottom.

Thrusters are disabled.

Thunderstorms threaten nearby.

If they come much closer they will have to abort the dive.

After 40 minutes, there's still no sign of any creatures.

Is it too shallow after all?

Don't waft that light on it.

Whoa! It would appear... Oh, there's one right there.

There's two in front of me now. As a matter of fact there's of them. One is hitting my backside.

They're very energetic, it's as though

they think this meal isn't gonna last long. I better take advantage of it while I can.

Nearly blind, candiru-acu tracks its prey by scent.

Its streamlined body allows it to writhe, gorging inside its victim.

I can tell you this, things are starting to heat up. We now have

candiru all going after this fish in front of me, grabbing it and twisting

and turning. They're going after the fish so enthusiastically that there's no way I could get this close

if I wasn't wearing this helmet.

They've eaten a hole in the top of the fish, now they're popping through the skin. It's amazing.

So are they eating it from the inside out?

Looks like maggots.

Yes, I would say they are eating it from the inside out.

Oh, my gosh! They're going after my stomach belt.

They're getting just a little bit too close for comfort.

Perhaps only their wet suits are saving the divers, in water infested with candiru-acu.

Although the reputation of the piranha is legendary,

could it be that these are the true monsters of the Amazon?

I'm just glad that these are scavengers and not predators

because I can't imagine that piranha are any more aggressive

than the candiru.

THUNDER ROLLS

The weather topside is deteriorating fast.

I'm gonna leave now and I'm gonna go back up because

this has been quite an experience and I want it to remain a good one.

OK. We will see you at the surface. Everyone here is standing by.

They're on the surface.

Going to extinguish the light now.

There we go.

Yeah, you're there.

-Woah.

-You OK?

Holy cow! If I had known about that

when I first came here I would have worn chain mail on every dive.

You don't dare go down with a cut.

I mean, they are just...

It was quite dramatic and I've done many, many dives all over the world

and I think that has to go down as one of the most disturbing.

They have good reason for their concerns.

Candiru-acu are tenacious to the extreme.

They're still in it.

They continue to devour the bait even when it's back above water.

Look at it now!

The expedition is nearly over.

In five short weeks, the 50 team members have voyaged 3,000 kilometres.

They've experienced the incredible variety of Amazon wildlife at first hand.

That was pretty spectacular.

That was a good, fun dive.

All right, let's find some fish!

Over 100 species have been filmed, many for the first time.

They've discovered fish completely new to science,

but all this is only scratching the surface.

There are thought to be another 2,000 species still to be recorded.

In this eerie world of the strange,

who knows what extraordinary creatures may yet be found?