Australia Swimming with Crocodiles

'Crocodiles - giants of the reptile world.

'The largest and most dangerous of them all is Australia's saltwater croc.'

-Why's he opening his mouth now and looking at me?

-He's looking at you.

-Is he about to launch up?

'Over 100,000 crocodiles now roam the waterways of northern Australia,

'and attacks on humans are inevitable.'

This is crazy.

'I'm part of a team trying, for the first time,

'to study their mysterious lives underwater.'

It's really quite something to be...

this close to a saltwater crocodile.

'It's an expedition fraught with risk.'

Must be just a couple of metres away

from this amazing piece of engineering.

'But could it lead to a very different understanding

'of these magnificent creatures?'

I really do think there's something very beautiful

about saltwater crocodiles.

'I've arrived in Darwin at the start of a ten-day research expedition

'in Australia.

'This coastal city is the capital of the Northern Territory.

'Thanks to a recent mining boom,

'this area has become a popular place to live.

'But not without its drawbacks.

'This is the heart of croc country.

'Hunting crocodiles was banned 40 years ago,

'and now, man and beast compete for territory.

'There are crocs in the harbour

'and sometimes crocs on your boat.'

After you.

Always a gentleman.

'I've come to the Adelaide River with Dr Adam Britton,

'a leading crocodile authority

'for my first encounter with his prehistoric neighbours.'

This is one of the Jumping Crocodile Cruises on this river.

And so a lot of tourists come here, from all around the world,

to see saltwater crocodiles jumping in the wild.

They can push the entire weight of the crocodile out of the water,

usually at least half of its body length.

Just with that one little sentence there, you've totally scared me!

You're telling me it could leap into this boat, potentially?

He could get his jaw on here quite happily.

-And, in fact, people...

-Move my arm away.

-..People have been attacked, in their boats, by crocodiles.

-By saltwater crocodiles?

-Jumping over the side of the boat.

'The crocodiles have come to recognise the tour boats as a predictable source of food.'

Now, what she's doing is splashing the meat on the surface of the water.

The crocodile, he's probably just under the boat, actually.

And he can actually pick up those vibrations, and so he's going to swim up to that.

He's going to associate that with a potential feed he's about to get.

Woah, woah, look at that!

Look, he's biting onto the boat.

Look at the shape of his head. He's really gnarly.

He's quite wide and broad.

Look as his body.

He's got a very dark-coloured body and a really light head.

So now he's on the surface, he's completely visual. So he's purely using his eyes.

And he can see that above his head, and so he's tilting his head up.

And what he's doing is his body is sinking in the water,

and he's putting his tail underneath him and then swimming upwards.

But you can see how heavy this crocodile is.

And so it requires quite a bit of power.

How heavy is this, do you think? What sort of length, do you know?

This guy, he's probably somewhere between...

500, 700 kilos.

Maybe even heavier than that.

That's half to three quarters of a ton!

Yeah. He'd be half a ton at least.

'That's ten times heavier than I am!'

They do do this naturally.

They hang underneath birds and fruit bats,

and they look up at it like that,

and then they'll swim upwards, literally.

Can't get over the size, the power, and the fact he's launching itself out of the water like that.

I never expected a crocodile to do that.

Why's he opening his mouth now and looking at me?

-He's looking at you.

-Is he about to launch up?

I wouldn't hang your head over.

I don't think I will, to be honest!

He wanted me for lunch, didn't he?

Well, look at his tail. He's got some bite marks...

-Is he about to launch myself at me?

-I certainly wouldn't be sticking your arm over the side.

'Adam is the lead member of our research team here.

'He's been studying crocodiles from the surface for 15 years.

'But this will only ever give limited insight into their behaviour.

'And, with the number of problem crocodiles at an all-time high,

'it's vital that we establish a new approach to learning about them.'

So if we CAN get in with the saltwater crocodiles...

you know, what can you learn from this?

Why are you so keen to try this?

The whole purpose behind this is to say,

"Well, we don't...

"understand as much about crocodile behaviour underwater as we thought we did."

All the way out here, I was thinking, "We're not going to get in with them, are we?"

And then you look at the murkiness of this water.

And, quite frankly, it's a terrifying prospect at this moment.

'Gaining a first-hand understanding of the crocodile's underwater world seems impossible.

'But our recent expedition to Africa

'makes us think this might be achievable.

'In the Okavango swamp of Botswana,

'Adam and I joined crocodile diving expert Brad Bestelink.

'Incredibly, in these clear, cool waters,

'Nile crocodiles - which would kill us at the surface -

'allowed us to approach.'

One of the most feared creatures on the planet.

And it's there!

'Once on the river bed,

'these man-eaters didn't appear to see us as prey,

'and we could study their senses, movements

'and where they choose to hide without being attacked.'

Look how close! I feel I could just...

reach out and touch it. I could!

Oh, it's moving off. Slowly.

'But compared to these Nile crocodiles,

'the saltwater croc is a very different beast.

'It's MUCH bigger.

'The largest reptile in the world.

'And aggressively territorial.

'It's day two of our expedition,

'and Brad Bestelink joins us in Australia.

'His croc diving expertise will be essential

'in our attempt to dive with saltwater crocodiles.

'We meet at Adam's place on the outskirts of Darwin.'

Can I say, when you spoke about your house in Botswana, I had this image of a little terraced house.

I didn't realise you were in the wild!

We're in the middle of the bush, basically.

'For the last five years, Adam has kept crocodiles for behavioural research.'

What is this?

Well, this here...

this is actually where we keep our crocodiles.

My heart's already pounding, can I just tell you?

I can just sense that it just looks really weird.

Well, there are two saltwater crocodiles...

in here.

But the male,

his name is Smaug,

and he is 15 feet long.

That's bigger than anything we saw in Botswana.

Certainly bigger than anything we got in the water with in Botswana.

'Before we attempt to dive in the wild,

'Brad and I want to get a handle on their behaviour,

'but with a fence to protect us.'

I am actually really nervous again.

I thought having dived with wild ones in Botswana kind of overcome that.

I'm already just a bit nervous going back in here.

And why am I doing this now, then?

Well, what I want to show you is

what a crocodile can do when it really wants to be a crocodile.

He is going to be tuned into attacking, to feeding. That's what he's going to be anticipating.

And it'll be a very sobering experience

because he can move very fast and with a huge amount of violence.

'While I'm in the water,

'Adam is going to get Smaug to display some of his most extreme behaviour.

'Not a comforting thought.'

Well, this is Smaug.

Waaah!

Just look at those teeth there!

Just in front of me here is a 15 foot crocodile!

In this tiny little pond.

That is properly prehistoric-looking.

Just the size of those teeth is extraordinary.

Look at him staring at me!

It's actually quite unnerving.

'While I'm inches from his jaws,

'Adam's going to show us just how fast Smaug can react.'

So what we're going to do is...

a surface disturbance test.

Basically, I'm going to throw this stone in the water, next to his head.

It sounds a bit more impressive like that.

And what crocodiles have got is

all these sensory organs around their jaws.

And they pick up pressure changes, particularly pressure changes at the surface.

So if you're a wallaby and you're coming down and taking a drink of water,

soon as your lips break the water,

it's going to fire those receptors off,

and the instinctive response is going to be to launch and grab.

And what I'm then going to do is

I'll throw this, and he'll expect something to hit the water.

And soon as he does, you'll see him strike.

-Should be an interesting experience.

-Stuff that I would never see in the wild.

Not the kind of thing you want to see...

Want to see in the wild!

There we go.

Wow!

That is incredible!

So that's Smaug.

That's a bit different to Botswana, isn't it?

Yeah, that's Smaug at full speed.

He's huge!

That is like a dinosaur's head.

I'm hoping that this doesn't put you off the idea of trying to dive with these animals in the wild.

-Maybe we'll go for a slightly smaller crocodile?

-Yes.

This is not to be taken lightly, any of this.

And the whole idea of doing this...

I mean, I know how he reacts here.

So we do have to be extremely careful.

'Smaug gets rewarded for his demonstration

'with a snack.

'One entire chicken downed in seconds!

'It's been a good practice run,

'but research on Smaug in this artificial environment

'can only tell us so much.

'Our goal is to observe a crocodile underwater in the wild.

'Brad will now search for a diving location with clear visibility...

'and lots of crocodiles.

'I also hit the road.

'I want to investigate exactly what the explosion in crocodile numbers

'means to the local population.

'Many Darwin residents favour a mass cull.'

Morning, guys.

'On my way out of town, I meet fishermen

'who've had terrifying experiences with crocodiles.'

I mean, crocodiles are sneaky things.

Worst thing I would say,

for every one that you see, there's 20 you don't.

I got followed out of the water at Buffalo Creek once.

I had two, three minutes to think about life, the universe and everything.

But yeah, I thought I was going to die that day.

Every time I turned around, it was there.

'Later that day, I meet up with Adam,

'240 kilometres east of Darwin

'in Kakadu National Park.

'Kakadu is another area

'where crocodiles and humans regularly collide.'

So, where are we now, Adam?

This is the East Alligator River.

And this is the eastern boundary of Kakadu National Park.

So it ends right over there, at the low water mark.

And then, just behind you,

you've got a crossing, and it's called Cow's Crossing.

And why do crocodiles choose to congregate here?

The crocodiles are here for the same reason that these guys fishing are here.

There's a lot of fish, and they're quite easy to catch.

You'll see a lot of them,

they actually hold their arms out, like that, as they're swimming.

And if a fish actually swims into this area,

if it gets close to their jaws and touches their jaws,

then they can detect the pressure and grab it.

And also, if it hits either of their arms here, again,

they can snap over and grab it.

So they've got quite an amazing fishing net technique that they're using.

And it's actually quite an infamous place because someone was killed here by a crocodile,

and, as you can see behind us, there's a lot of crocodiles here.

And what's known about that attack?

Well, he was trying to cross the river at the crossing.

But the water was very deep,

and when he was going across the river,

and this crocodile cruised up behind him,

grabbed him on the head and pulled him under.

So it was quite a shocking attack, actually.

'Despite the fatal attack,

'fishermen here ignore the warning signs.

'And with so many people coming to the river,

'the crocodiles are losing their fear of boats...

'and man.

'Heading further into Kakadu National Park,

'I'm soon to witness yet more evidence of the increasing conflict

'between humans and crocodiles.'

Just had a radio call from Adam,

who's somewhere up ahead,

and he's with a park ranger called Gary

who has something to show us.

-Hi, Gary.

-How're you going? Pleased to meet you again.

-Hi there, I'm Ben.

-How're you going, Ben? Gary.

-Good to see you.

This is the crocodile.

We had a call out yesterday to a dead animal

about 120Ks north of here.

The most senior traditional owner there was...

concerned about the death of a big croc.

She's absolutely furious about it.

Basically, some person's just shot it at the crossing there.

-Shot it?

-Yeah.

You can see the bullet hole, just in front of the eyes here.

It's an absolute tragedy when that occurs to one of these

really big, important boss crocs.

'Judging from the size of its head,

'this crocodile must have been enormous,

'even longer than our Jeep.'

You're really sad about this?

Oh, yeah. Crocs are special, but really big crocs are unique.

They well and truly earn their right to be boss croc.

I mean, a high percentage of crocs don't even make it to six foot.

So, for an animal to get to 5.1 metres,

and then be dominant in an area for years, decades,

you well and truly earn your right to be boss croc.

So it's a very sobering reminder...

of just how some people feel about crocodiles.

'It's a shocking sight.

'This crocodile's home was very remote,

'miles from a populated area.

'This is a killing fuelled by real hatred.

'But not everyone feels this way about these animals.

'Kakadu National Park is Aboriginal land,

'where man and croc have lived side by side for 40,000 years.

'Here, the crocodile's role as the top predator is respected,

'rather than resented.

'I meet Auntie Goldie,

'the owner of the land where the large crocodile was shot,

'and Kakadu Park ranger, Jonathan Nadji.'

The crocodile that Gary found, you know that individual crocodile?

Yes, yes. I knew that he was there.

I just...

feel angry because I knew he was there...

protecting an area.

Sorry.

It's a bit... upsetting at the moment, yeah.

What Mum's saying is that that animal, basically, she knew it,

and every time she went to that area,

she would yell out to the animal and it would come, so she had a special bonding with the crocodile.

To us, that sort of thing is just like, yeah...

old people. Stuff like that.

..Our family.

Like, he'd been there, protecting that area,

and...

we respected it.

He respected us.

There seems to be a conflict between some people and crocodiles,

with human habitation and crocodiles.

But I gather that people can live in harmony with crocodiles.

There's no reason why they can't.

We do. We do. But there's other people that can't respect that law.

We just leave them alone.

They respect you.

And they quietly swim away.

'I'm moved by Auntie's distress.

'It's remarkable how attached people can become to a crocodile.

'The rangers in Kakadu may admire crocodiles,

'but they still have to deal with problem animals.

'That night, I joined Gary on patrol.

'Rather than shooting problem crocs,

'he's attempting a more humane approach.'

So, Gary,

what's the plan, how do you do this?

What we want to do tonight is

identifying potential problem crocs...

that may be hanging around the boat ramp.

And some of these crocs get quite habituated to fishing activity,

and they associate fishermen with an easy handout feed.

'Gary's aim is to find and scare the animal.

'It's his very own aversion therapy.

'But first, we need to catch it.'

-So, how do you catch a croc?

-We get right up on the animal.

Within, you know, two or three metres.

And then we put a harpoon...

we just put that behind the neck, under the skin.

It's unpleasant, but it's not too dangerous for the crocodile to have that on its skin....

-No, it's...

-It's got thick skin.

A crocodile, what he experiences in his lifetime,

this is pretty insignificant.

'I'm on croc spotting duty...

'looking out for movement in the water.'

-There's one.

-Oh, yeah.

Keep going, keep going, keep going, keep going, keep going.

Keep going.

Neutral, neutral, neutral.

'We missed him,

'but quickly pick up his trail again.'

Bubbles there?

-There were some bubbles as it popped down.

-You see the bubbles?

-Yep.

That's going to go. Yep, got him.

When he comes up, Ben, bright light just goes straight on his eyes.

Straight on his eyes, OK.

This is crazy.

Amazing! Can't believe they've got a...

two-metre croc on the end of that line!

'It looks harsh...

'because it is.

'But I know this rough handling is for the crocodile's own good.

'He'd end up being shot if he attacked anyone.'

Happy with the knot?

Just hold him there, look.

That'll do, yep.

And hold him there look. The next phase is to shut his jaws,

and once we do that, it makes handling the animal a lot easier.

So all we're going to do is just put a zip tag around both jaws.

This is the most dangerous part.

It's just a matter of getting the jaws shut,

and then we can start doing things with him.

And we're happy with that.

But this process now is just giving the animal a bit of a scare.

It's probably thinking, "What the hell's happening on?"

It's probably likely a death experience. Then we let him go.

And, basically, this is what you want,

make him a bit more wary of people.

All right, when he comes inside the boat,

just keep him really still.

We don't want any head swing happening.

We don't want him to damage himself too much.

Exactly. But, more importantly, don't want him damaging us.

-OK.

-All right. Let's go.

All right, let's go.

Straight down.

OK.

On the head. Give us this body.

Push down on the head hard. Both hands.

OK. Yep.

Now push down on the snout.

Back to the boat ramp, driver.

He's quite heavy, isn't he? Where are we going?

All right, now come down, Jonno.

What we're going to do is we're going to secure him first

to this pole, right here.

OK, now put it round, same we did the other day.

And what we want to do is just secure his head

cos he's really going to think.

Right, when he goes down...

pull up.

Now, bring his...

That's it, tie him tight.

That's it.

Very good.

OK. Now, roll him towards the...

cos I want to see his underbelly.

-Like that?

-That's it.

'The final part of the process is sexing the crocodile

'to determine its gender.

'This is probably uncomfortable for him, too.'

-Finger in there, Ben.

-Yep.

Right in there, and just tell me what sex it is.

What am I feeling for?

Harder. You'll be feeling it yet.

Bit more. Long and hard?

-Yep.

-What do you reckon?

Male?

Wow. So I've just sexed a crocodile.

It's just incredible, cos this...

is as close as I'm ever going to get to a dinosaur.

So I just want to have a look at every single part of it

cos it is a fascinating, incredible creature.

'These are beautiful animals.

'Their massive webbed feet are used for steering and walking underwater.

'And their 66 teeth are constantly replaced.

'They get through 3,000 in their lives.'

So we're ready to release him?

Yep. This is probably just as dangerous as tying their jaws up.

Just keep him firm there,

and just keep his legs pulled back along his tail.

He's starting to get... Ooh!

All right, hold him. Just tight, tight.

Yep. Waah!

-You can feel the power there?

-Yeah, that's quite a lot of power.

-Sit on him.

-OK, like that?

-That's it.

Wow.

That was more powerful than I am!

When something like this grabs you in the water, people think it's a small croc.

If it grabs you in the water, you've got no hope. At the water's edge, the same.

That would have flipped me over just then.

Especially when it's got a limb or a leg,

it'll do a succession of quick rolls.

Mmm-hmm.

And basically, dislocate or break your leg...

or your arm.

Maybe I'll just undo this one first.

OK, you start walking.

Yep.

Go walk straight back up.

Just go where Ralph is, on your right.

'He doesn't sound happy.

'Having been tied up for so long,

'anything could happen.'

Back, back, back, back, back.

Keep coming! Back, back.

Slide, slide.

'Unluckily for this crocodile,

'the water's in the opposite direction.

Come on, here.

That was an angry croc, but that's the point, I suppose.

Here!

'He finally gets his bearings

'and makes it back to the river.'

That's just a very surreal night, really.

This whole thing's been very surreal.

But, naturally, the crocodile...

went mental when it was released.

And what I thought was fascinating is of all the people that were here -

cos a few people have turned up, there's police, everything's here -

it went for Gary.

Which means it seemed to have worked.

'Hopefully, that crocodile won't risk approaching

'people or boats again.

'But the problem is too widespread

'for this approach to work everywhere.'

Do you think there's a slight problem

that not enough people realise

or respect the dangers of crocodiles?

When people are coming,

and if they're thinking that the waterway's solely for them,

I think that's a really sort of ...

..greedy, selfish attitude.

This is Aboriginal land, first and foremost.

Consider yourself a guest,

understand that crocs are there

and just be safe.

And have a lot of respect. Don't sort of think it's all yours.

'Today, I'm rejoining our underwater research team.

'The plan to get underwater with crocs has run into difficulties.'

What it is,

I left Darwin, went the whole way to the Flora River,

which is meant to be...20 metres visibility this time of year.

It's THE clearest river in the Northern Territory.

-And now?

-Not the clearest river in the Northern Territory!

Probably three, four metres at most.

Really? What are all the rivers so bad?

Well, we had a record wet season this year. So much rain,

and it brings all kinds of silt and sediment down with it.

-And is there anything suitable that you found?

-Nothing. Nothing suitable.

I mean, nothing that we could consider diving...

-with salties on.

-So what's the next best option?

I mean, the other possibility

is up here, on the Cobourg Peninsula.

There's actually been a few crocodile attacks here.

-That means there are saltwater crocs up there.

-There definitely are.

-And big enough to eat you.

-And hopefully clear water?

Yeah. If we find crocodiles, clear water and the conditions are right,

and we've got luck on our side, then maybe we'll find the right conditions.

Oh, I'm getting all excited! This could be cool.

'So, we're travelling 320 kilometres north of Darwin

'into a very remote area.

'We now have just a few days left to find clear water

'and attempt our pioneering dive with salties.'

OK, another adventure.

Oh, off again.

'We've pinpointed what could be a perfect diving location.

'But the wild crocodiles there are an unknown quantity.

'Most people avoid the waters of the Cobourg Peninsula.'

It's a bit scary because we are entering an area

with the most dangerous marine life in the world -

box jellyfish, sea snakes, various sharks.

So we're kind of upping the danger, but, you know,

the potential for having an encounter is increased,

so I really don't know what's going to happen here.

'After touching down late afternoon, we head straight out to the coast

'to look for signs of crocodile activity.

'These beaches look perfect for sunbathing

'and Adam tells me that crocodiles bask here

'in much the same way.'

-Hey, guys?

-Yeah?

-Is that one there?

-Oh, yeah.

-Cruising across the middle.

-Is that it?

So what sort of size do you think that one is?

Probably over three metres.

-What do you think it's doing now?

-Well, he's actually moving away.

He may have actually been on the beach. And he's now heading out.

He may have heard us coming down that hill.

And he's slowly heading out across there. He looks like he's heading into deeper water.

Yeah. Could we go out, in a boat now, and jump in the water there?

I don't think it's got the right sort of topography.

If we had to find them out there, if we got in the water he'd move, or he'd move away from the boat.

If you pick them up on big open flats like this,

they'll move quite quickly. It's going to be very difficult to actually get in the water.

'If it's not possible to control a dive with crocodiles swimming out at sea, then tomorrow

'we'll have to hunt for them in enclosed waterways.

'Our plan is to scour the creeks of the Cobourg Peninsula.'

Excited?

'Time is running out and we're determined to attempt our wild dive.'

What do you think our chances are?

If we get visibility, pretty good eh?

-Yeah?

-Yeah, I'm dying to get some clean water.

-That's really the thing that we're hinging on.

-Yeah.

'We're entering very dangerous waters,

'and are joined by safety divers and medics.'

OK, I'm ready to let go here.

'We're looking for a croc less than two metres long.

'From Brad's African experience,

'crocodiles are unlikely to attack anything bigger than themselves.'

There's a few things on the beach there, that could maybe be crocodiles.

It's about the sort of time that you'd expect them to be basking.

You see it here? It's right in front of us.

-Yeah, it's a croc, eh?

-It's a croc?

-It's a bloody croc.

-Right there?

-Is it? Is it a croc?

-Yeah.

-Yeah.

-Yeah, that's a croc for sure, eh?

-Here, here, here, here.

I think it's just here.

That's unbelievable. We've seen a crocodile here already. Woah, I don't want to fall in this now.

Not without my spike.

'The shallow waters in these bays are teeming with life,

'much of which, as our Australian camera crew remind us, is deadly.

You have to wear shoes or wet-suit boots because this is stonefish country.

-Am I OK in flip-flops?

-They're very, very dangerous.

Don't pick up any shells or anything, they could be cone shells - they'll kill you.

You could get stung by a box jellyfish, that will kill you too.

Watch out for sea snakes, OK? And, of course, there's crocodiles.

You've already seen one. So...

Otherwise there's nothing much to be concerned about.

That's reassuring(!)

'We're entering a clear, saltwater creek.

'Unlike the areas I've already visited,

'the crocodiles have rarely, if ever, seen a human here.'

So we just need to keep the voices down

so that if we see a crocodile, it doesn't hear us coming first.

'The water in these creeks is tidal,

'and only deep enough for us to dive in for five hours.

'We have to leave before the water levels drop or we'll be stranded.'

'Time is against us.

'But we finally see a hopeful sign - a clear crocodile track.'

-Wait.

-Don't take too many folk out for the footprints, keep them clean.

These look actually like the scales on the underside of the tail.

-So the crocodile's actually swung his tail around.

-Mm-hm.

So we know there's a croc around. We've seen a croc.

It's just a matter of finding him

and the right vis at the right depth.

-Yeah.

-Shall we try back in the creek?

-Do you think the tide might be...

-Let's go round that creek again.

'It's the track of a fairly small crocodile -

'the perfect animal for our first dive.'

'Spooked by our approach, it could be hiding in the water below.'

We can't see them from the surface,

we'll just have to go and have a look for him underwater.

'Brad's croc-diving method, developed in Botswana,

'is to get into deep water as quickly as possible.

'Crocodiles mostly attack at the surface

'and are less likely to see us as prey underwater.

'While the waters are still deep enough to dive,

'this could be the chance we've been waiting for -

'to see a saltie's underwater behaviour.'

'In these unknown waters,

'only the most experienced divers head into the mangroves...

..'while I keep track of their movements from the boat.'

They've all got their croc spikes and we have to follow

exactly the same routine that we've always done.

'The team stick together and slowly enter the mangroves.

'The crocodile could be anywhere.

'In the underwater gloom, it's not proving easy to find.'

Obviously the difficulty that we have here is that we're in a mangrove swamp.

But if you just look over there, that's open water.

We've got this huge, vast area that the crocodiles can escape to

and we've already seen them out in the sea.

So it's very difficult to pinpoint them to one area,

it's a vast expanse.

'In a break from protocol, the team spread out.

'But still there's no sign of the crocodile.

'And, as the tide goes out and water levels fall,

'we're forced to abandon the dive.'

Get this forward.

Pity that there was no contacts for the study.

Yeah.

'We've been defeated by the conditions.

'It's a huge disappointment.

'With today's diving window well and truly closed, we head for home.'

-Here it is, here it is.

-Here he is.

-Right next to us.

-Wow.

-Did he hear that, do you think? Or it spotted us?

-Yes. He would have heard that.

It's like this whole thing is like it's so tantalising.

-We've gotten so close with this.

-Teasing us.

-We have to remember...

-Plenty of clear water.

But we have to remember we are dealing with wild crocodiles,

that's the thing, and it's just pushing it a little bit too far.

'We've got just two more days together in Australia.

'The conditions in Cobourg are too challenging to conquer in our time frame.

'But a small opportunity has opened up back in Darwin.

'This morning, Adam got a call.

'A male saltwater croc has been caught trying to get into Darwin harbour.'

They do actually have a crocodile that the rangers have pulled out of the harbour.

It is possible for us to actually dive with that crocodile under controlled conditions

and so we can actually go in there and we can see

whether the animal behaves in a way that we'd expect it to.

-I'm in.

-I'm in.

-It's the next best thing.

-I mean, just to get that experience will be worthwhile.

-OK.

'We can place this crocodile into a clear water billabong.

'The crocodile won't be in its own territory,

'but it will give us the chance to try and dive with a saltwater croc in the wild.

'We head back to the city, where, in a holding pen,

'there's a wild, angry, three-metre-long crocodile.

'A problem crocodile caught in the harbour

'is usually dispatched to a croc farm to be killed.

'We've arranged a temporary stay of execution

'for us to attempt our underwater research.

'But first we've got to get one fiery reptile back into the water.'

Come on. Open your mouth. Come on, bit further. Bit more.

Here it comes. Whoop.

Here we go.

Come on. OK. So we're going to need to pull him up into this area here.

This is the danger zone. So if you're there, just make sure you've got an escape route.

-Going to start rolling.

-Winding himself up.

-Yeah.

Got to be careful he doesn't... I don't want him to injure himself on the...

-Do you want to do the honours?

-Yeah, all right.

-OK, you want to get it down? Get it underneath his lower jaw.

-Yeah.

Wait, I'll lift his jaw. Hold on, let me do it.

Let me just get the tip of his jaw. Hold on, wait a sec.

That looks better. Woah! That's good. Keep going on that one, big girl.

-OK, get him out now. Now that he's tied up nicely.

-Yeah.

Pull him out here. Let's get him out. Slide it off, OK, are you ready?

Now, bit forward in front of his front legs now.

Front of his back legs, sorry.

We have to be nice and calm.

-OK, now, Brendan, go.

-Push down. Press down, down.

'The crocodile rolls to avoid capture.

'This is also how crocs spin to rip flesh off its victims

'in a death roll.'

Ready? One, two, up.

GRUNTS OK.

-Oh, he's a bit heavier than the usual croc I get in here.

-Quickly.

-OK.

-There we go.

-That's it. Good job, guys.

'Our diving location is a clear water spring.

'It's the perfect site for us to release our crocodile for a short time.

'We know so little about the underwater world of crocodiles

'that any new information about these ancient predators

'can only help the conflict between people and crocs.'

That's fine. Put that on afterwards.

'Brad's dived with crocs in Africa for five years.'

I'm happy with it.

'He knows how Nile crocodiles react,

'but diving with a saltie is virgin territory.'

Really it's about learning their behaviour.

See how they react to divers

and the presence of a person underwater.

That's the most important thing and this is just a small window

that we can learn from, and it's, I think, one that has to be taken.

I'm really excited.

I came out here to dive and, yeah, I'm really looking forward to getting in.

'To transport the crocodile and get it into the spring,

'we've put a temporary safety measure in place.'

I mean, obviously you know that there's a little bit of fishing line

that you've got taped around the crocodile's jaws,

but if you get really close to that crocodile, simply the power

that the animal has in his neck muscles, and the weight of the head -

which is pretty much solid bone - it's still very capable of inflicting a huge amount of damage.

There's still tension that you have in the water around it.

'And, at some point, the nylon line WILL come off.

'We need to quickly get away from the kill zone at the surface

'and into deep water.

'We stick together and, very cautiously, set off in search of the crocodile.

'We have one very clear objective, to find out

'if the crocodile will allow us to approach.

'If so, then future wild underwater research is a very real possibility.'

So I'm just going to stay outside of his attack range.

And I'm pretty sure that he can see me.

'Normally the attack zone is half the length of the crocodile's body.

'So, for this initial part of the dive, we keep that distance.'

I'll just stay back a little bit. Just see what he decides to do.

'He decides...to do nothing.

'He seems unfazed by our presence

'and has taken up a position basking in the underwater sunshine.'

It's really quite something to be this close to a saltwater crocodile.

His eyes are open, he knows I'm here...

and is just sitting there.

'As he moves away, we tentatively follow.'

Just watch him coming up to the surface, very slowly.

Take a breath of air. Look how slowly it creeps up that bank.

Really amazing sight, that.

This is a wild crocodile, we are in a wild billabong

and it seems to be acting like the Nile crocodiles in Botswana.

'We can observe how he conserves energy by walking on the river bed,

'rather than swimming.'

He's trying to get his bearings.

And then, every so often, he's going up to the surface to take a breath.

He's not staying there very long. And he's going back down again.

And then resting again.

'But now is the real test.

'Will he allow us into his attack zone without striking?'

And I'm pretty sure that he can see me. Look at that, OK.

So this guy is completely not bothered that I'm here at all.

'The answer is yes.'

Just is awesome to see.

'Brad believes that crocs see divers as other crocs in the water,

'rather than prey.

'Whether or not that's true, this one has absolutely no interest in attacking us.'

So easy just to touch their tail.

It would be so easy to take a tissue sample.

Just reminds me again of what potentially could be done in terms of research.

'Studying crocodiles in their underwater world,

'revealing new information on their senses and behaviour,

'will push the boundary of our knowledge about this extraordinary species.'

Today, he allowed a brief glimpse into this sub-aquatic, watery world.

I see a very different side of these predators.

Crocodiles are often described as the ultimate killing machines,

and they are. But, here, underwater...

..is a very different world.

Wow. Well, that was pretty special.

Just amazing to kind of sit there and see it in a natural habitat.

And I think many people have this image that it would be

going for us and tearing around underwater, but it's actually,

once it's underwater, it's a very placid creature.

And I think that's what this whole journey's been about.

It's been about discovering that crocodiles

are very different from those creatures that we see.

You know, 80% of a crocodile's life is underwater

and so little is known about that.

Well, it's quite magical, I think, to be underwater with a crocodile.

You're getting a view that most other people would never see.

If we can find areas where there are saltwater crocodiles,

and there's clear water, and the conditions are right,

then the whole world is suddenly going to open up to us

in terms of what's possible with those animals.

This crocodile would normally be taken away to be killed.

But having dived with this beautiful creature,

none of us want to see that happen.

So we devise an alternative...

On our final morning in Australia,

we put our crocodile rescue plan into action.

It's funny how things turn out.

I haven't been able to get out of my mind that image of that...

enormous crocodile head that was shot,

and how distraught Auntie was

on discovering that her favourite crocodile,

that she referred to as her family member, had been killed.

And then I was diving with that crocodile yesterday,

that had been caught in the harbour,

and again I couldn't bear the thought that

this croc might go to the farm and be turned into

a belt or a handbag.

So Adam has been able to...

sweet-talk everyone in the country

and called Auntie, and said to her, listen,

we've got this crocodile, could we release it on her land?

And, unbelievably, everyone has said yes.

So I'm now heading back up towards Cobourg

and we're off to release one...

that I've called Ludo. I've spent so much time with it I had to give it a name.

Everyone called it "the crocodile that was caught in the harbour", so I've called it Ludo, after my son.

So at this very minute,

Ludo the crocodile is in the back of Adam's car

with a magnet on its head.

You couldn't make it up, could you?

Ludo also gives us

a great opportunity to research a crocodile's homing instincts.

We'll see if a magnet on his head

will temporarily confuse his magnetic sense of direction.

Our hope is that this will stop him returning to Darwin Harbour.

If he's caught back there, he'll be killed.

We're going to release him a long way

from where he was trapped,

and use a GPS device to track his movements.

-Hey, guys, how are you?

-Hi.

-Good to see you. How are you all?

-How you going, Ben?

-Really well.

-Listen, thank you very much for doing this.

-No, it should be good.

Fantastic for you as well, to be able to actually put a tracking device on it.

Yeah, I'm very interested to see whether he goes straight back in that direction

or whether he looks around a bit and has no idea where he is.

-Shall we go and get the croc out?

-Yep.

-I'm really excited about this.

-He might be a bit fiery, so...

-OK.

'Auntie keeps watch over the arrival of her new crocodile.'

-This is the magnet...

-Oh, yeah.

It's actually it's a very hi-tech piece of equipment,

it's an old stereo car speaker from my old Honda. BEN LAUGHS

So that's been sitting on the back of his head,

so hopefully any ability he has to orientate using magnetic fields

would have been completely wiped out.

-So he'll probably think he's still back in Darwin.

-Wow.

'Crocs have almost homing pigeon-like instincts,

'and relocated ones often find their way home.

'We'll see if this magnet stops Ludo from heading back to Darwin Harbour.'

-OK...

-Yeah?

-Yup.

-Is this a good croc to put a GPS device on?

-Yeah.

He's the kind of animal that we want to find out a lot more

about what's making him move, where he's going to,

the kind of habitat he's trying to find.

And these guys are going to be very interested in what we find out.

-What's this one called?

-This crocodile's called Ludo.

L-U-D-O.

Do you realise this crocodile will probably live as long, if not longer, than your son.

That's pretty crazy, that.

-So for his entire life he'll have a crocodile swimming around here.

-That's too cool.

'This transmitter will send out a GPS signal every hour.'

OK. It looks good.

It's flashing, so it's operating...

-So this is all making it watertight, isn't it?

-Yes. This will fall off eventually.

It's not going to be here for the next 60 years.

And hopefully in that time we'll get some really great information

from it. And, you know, Ludo will be... He's a pioneer.

-I smile whenever I hear that. It's brilliant.

-He's a pioneer.

Our preconceptions about crocodiles are very different to the reality.

And this kind of thing will help to fill in the blanks.

OK, one, two, three...

Right up.

-OK?

-Yep.

-Just here, eh?

-Just here?

-Can you go back a bit?

-Yeah.

-Hold him tight.

-OK, drop it, Ben.

-Drop it? OK.

There he goes...

Go on, boy...

I'd say see you later, alligator, but we actually don't want to see him again.

So I'll just say good luck. Bon voyage!

Oh, look at that. He's tasting the salt water now.

That's really cool. What an amazing experience this has all been.

I feel so lucky to have shared the whole thing -

right from the beginning, from my time in Botswana, you know,

when I was terrified of the crocodiles,

terrified about going in. I just remember the heart palpitations.

All the way to this beach in Australia,

having let a crocodile free in the ocean to do science for us.

I'm strangely moved. I never thought I'd say that about a croc.

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