0:00:02 > 0:00:06'Crocodiles - giants of the reptile world.
0:00:10 > 0:00:16'The largest and most dangerous of them all is Australia's saltwater croc.'
0:00:16 > 0:00:21- Why's he opening his mouth now and looking at me?- He's looking at you. - Is he about to launch up?
0:00:21 > 0:00:26'Over 100,000 crocodiles now roam the waterways of northern Australia,
0:00:26 > 0:00:29'and attacks on humans are inevitable.'
0:00:31 > 0:00:33This is crazy.
0:00:39 > 0:00:42'I'm part of a team trying, for the first time,
0:00:42 > 0:00:46'to study their mysterious lives underwater.'
0:00:46 > 0:00:49It's really quite something to be...
0:00:49 > 0:00:52this close to a saltwater crocodile.
0:00:52 > 0:00:55'It's an expedition fraught with risk.'
0:00:55 > 0:00:58Must be just a couple of metres away
0:00:58 > 0:01:01from this amazing piece of engineering.
0:01:01 > 0:01:03'But could it lead to a very different understanding
0:01:03 > 0:01:06'of these magnificent creatures?'
0:01:06 > 0:01:09I really do think there's something very beautiful
0:01:09 > 0:01:11about saltwater crocodiles.
0:01:25 > 0:01:30'I've arrived in Darwin at the start of a ten-day research expedition
0:01:30 > 0:01:32'in Australia.
0:01:32 > 0:01:36'This coastal city is the capital of the Northern Territory.
0:01:37 > 0:01:40'Thanks to a recent mining boom,
0:01:40 > 0:01:43'this area has become a popular place to live.
0:01:43 > 0:01:46'But not without its drawbacks.
0:01:46 > 0:01:49'This is the heart of croc country.
0:01:51 > 0:01:55'Hunting crocodiles was banned 40 years ago,
0:01:55 > 0:01:58'and now, man and beast compete for territory.
0:01:58 > 0:02:01'There are crocs in the harbour
0:02:01 > 0:02:03'and sometimes crocs on your boat.'
0:02:05 > 0:02:07After you.
0:02:07 > 0:02:08Always a gentleman.
0:02:10 > 0:02:13'I've come to the Adelaide River with Dr Adam Britton,
0:02:13 > 0:02:15'a leading crocodile authority
0:02:15 > 0:02:19'for my first encounter with his prehistoric neighbours.'
0:02:29 > 0:02:33This is one of the Jumping Crocodile Cruises on this river.
0:02:34 > 0:02:37And so a lot of tourists come here, from all around the world,
0:02:37 > 0:02:40to see saltwater crocodiles jumping in the wild.
0:02:40 > 0:02:43They can push the entire weight of the crocodile out of the water,
0:02:43 > 0:02:45usually at least half of its body length.
0:02:45 > 0:02:49Just with that one little sentence there, you've totally scared me!
0:02:49 > 0:02:52You're telling me it could leap into this boat, potentially?
0:02:52 > 0:02:56He could get his jaw on here quite happily.
0:02:56 > 0:03:00- And, in fact, people...- Move my arm away.- ..People have been attacked, in their boats, by crocodiles.
0:03:00 > 0:03:03- By saltwater crocodiles? - Jumping over the side of the boat.
0:03:03 > 0:03:09'The crocodiles have come to recognise the tour boats as a predictable source of food.'
0:03:10 > 0:03:14Now, what she's doing is splashing the meat on the surface of the water.
0:03:14 > 0:03:18The crocodile, he's probably just under the boat, actually.
0:03:18 > 0:03:22And he can actually pick up those vibrations, and so he's going to swim up to that.
0:03:22 > 0:03:25He's going to associate that with a potential feed he's about to get.
0:03:25 > 0:03:28Woah, woah, look at that!
0:03:29 > 0:03:31Look, he's biting onto the boat.
0:03:31 > 0:03:34Look at the shape of his head. He's really gnarly.
0:03:34 > 0:03:36He's quite wide and broad.
0:03:38 > 0:03:40Look as his body.
0:03:40 > 0:03:44He's got a very dark-coloured body and a really light head.
0:03:44 > 0:03:48So now he's on the surface, he's completely visual. So he's purely using his eyes.
0:03:48 > 0:03:53And he can see that above his head, and so he's tilting his head up.
0:03:53 > 0:03:55And what he's doing is his body is sinking in the water,
0:03:55 > 0:03:59and he's putting his tail underneath him and then swimming upwards.
0:03:59 > 0:04:01But you can see how heavy this crocodile is.
0:04:01 > 0:04:04And so it requires quite a bit of power.
0:04:04 > 0:04:07How heavy is this, do you think? What sort of length, do you know?
0:04:07 > 0:04:11This guy, he's probably somewhere between...
0:04:11 > 0:04:13500, 700 kilos.
0:04:13 > 0:04:14Maybe even heavier than that.
0:04:14 > 0:04:17That's half to three quarters of a ton!
0:04:17 > 0:04:19Yeah. He'd be half a ton at least.
0:04:19 > 0:04:21'That's ten times heavier than I am!'
0:04:23 > 0:04:25They do do this naturally.
0:04:25 > 0:04:27They hang underneath birds and fruit bats,
0:04:27 > 0:04:29and they look up at it like that,
0:04:29 > 0:04:31and then they'll swim upwards, literally.
0:04:34 > 0:04:38Can't get over the size, the power, and the fact he's launching itself out of the water like that.
0:04:38 > 0:04:40I never expected a crocodile to do that.
0:04:42 > 0:04:45Why's he opening his mouth now and looking at me?
0:04:45 > 0:04:47- He's looking at you. - Is he about to launch up?
0:04:47 > 0:04:49I wouldn't hang your head over.
0:04:49 > 0:04:51I don't think I will, to be honest!
0:04:51 > 0:04:53He wanted me for lunch, didn't he?
0:04:53 > 0:04:56Well, look at his tail. He's got some bite marks...
0:04:56 > 0:05:01- Is he about to launch myself at me? - I certainly wouldn't be sticking your arm over the side.
0:05:02 > 0:05:06'Adam is the lead member of our research team here.
0:05:06 > 0:05:10'He's been studying crocodiles from the surface for 15 years.
0:05:10 > 0:05:15'But this will only ever give limited insight into their behaviour.
0:05:15 > 0:05:18'And, with the number of problem crocodiles at an all-time high,
0:05:18 > 0:05:23'it's vital that we establish a new approach to learning about them.'
0:05:23 > 0:05:26So if we CAN get in with the saltwater crocodiles...
0:05:26 > 0:05:29you know, what can you learn from this?
0:05:29 > 0:05:32Why are you so keen to try this?
0:05:34 > 0:05:36The whole purpose behind this is to say,
0:05:36 > 0:05:38"Well, we don't...
0:05:38 > 0:05:44"understand as much about crocodile behaviour underwater as we thought we did."
0:05:47 > 0:05:51All the way out here, I was thinking, "We're not going to get in with them, are we?"
0:05:51 > 0:05:54And then you look at the murkiness of this water.
0:05:54 > 0:05:57And, quite frankly, it's a terrifying prospect at this moment.
0:05:59 > 0:06:05'Gaining a first-hand understanding of the crocodile's underwater world seems impossible.
0:06:06 > 0:06:08'But our recent expedition to Africa
0:06:08 > 0:06:11'makes us think this might be achievable.
0:06:17 > 0:06:20'In the Okavango swamp of Botswana,
0:06:20 > 0:06:24'Adam and I joined crocodile diving expert Brad Bestelink.
0:06:27 > 0:06:31'Incredibly, in these clear, cool waters,
0:06:31 > 0:06:34'Nile crocodiles - which would kill us at the surface -
0:06:34 > 0:06:36'allowed us to approach.'
0:06:36 > 0:06:40One of the most feared creatures on the planet.
0:06:40 > 0:06:41And it's there!
0:06:41 > 0:06:43'Once on the river bed,
0:06:43 > 0:06:46'these man-eaters didn't appear to see us as prey,
0:06:46 > 0:06:49'and we could study their senses, movements
0:06:49 > 0:06:52'and where they choose to hide without being attacked.'
0:06:54 > 0:06:57Look how close! I feel I could just...
0:06:57 > 0:06:59reach out and touch it. I could!
0:06:59 > 0:07:02Oh, it's moving off. Slowly.
0:07:03 > 0:07:05'But compared to these Nile crocodiles,
0:07:05 > 0:07:08'the saltwater croc is a very different beast.
0:07:14 > 0:07:15'It's MUCH bigger.
0:07:15 > 0:07:18'The largest reptile in the world.
0:07:18 > 0:07:20'And aggressively territorial.
0:07:27 > 0:07:29'It's day two of our expedition,
0:07:29 > 0:07:32'and Brad Bestelink joins us in Australia.
0:07:32 > 0:07:35'His croc diving expertise will be essential
0:07:35 > 0:07:39'in our attempt to dive with saltwater crocodiles.
0:07:39 > 0:07:43'We meet at Adam's place on the outskirts of Darwin.'
0:07:43 > 0:07:48Can I say, when you spoke about your house in Botswana, I had this image of a little terraced house.
0:07:48 > 0:07:50I didn't realise you were in the wild!
0:07:50 > 0:07:52We're in the middle of the bush, basically.
0:07:52 > 0:07:56'For the last five years, Adam has kept crocodiles for behavioural research.'
0:07:56 > 0:07:58What is this?
0:07:58 > 0:07:59Well, this here...
0:07:59 > 0:08:02this is actually where we keep our crocodiles.
0:08:02 > 0:08:05My heart's already pounding, can I just tell you?
0:08:05 > 0:08:08I can just sense that it just looks really weird.
0:08:08 > 0:08:12Well, there are two saltwater crocodiles...
0:08:12 > 0:08:13in here.
0:08:13 > 0:08:14But the male,
0:08:14 > 0:08:16his name is Smaug,
0:08:16 > 0:08:18and he is 15 feet long.
0:08:18 > 0:08:21That's bigger than anything we saw in Botswana.
0:08:21 > 0:08:25Certainly bigger than anything we got in the water with in Botswana.
0:08:26 > 0:08:28'Before we attempt to dive in the wild,
0:08:28 > 0:08:31'Brad and I want to get a handle on their behaviour,
0:08:31 > 0:08:34'but with a fence to protect us.'
0:08:34 > 0:08:36I am actually really nervous again.
0:08:36 > 0:08:40I thought having dived with wild ones in Botswana kind of overcome that.
0:08:40 > 0:08:43I'm already just a bit nervous going back in here.
0:08:43 > 0:08:46And why am I doing this now, then?
0:08:46 > 0:08:48Well, what I want to show you is
0:08:48 > 0:08:51what a crocodile can do when it really wants to be a crocodile.
0:08:51 > 0:08:56He is going to be tuned into attacking, to feeding. That's what he's going to be anticipating.
0:08:56 > 0:08:59And it'll be a very sobering experience
0:08:59 > 0:09:03because he can move very fast and with a huge amount of violence.
0:09:08 > 0:09:09'While I'm in the water,
0:09:09 > 0:09:14'Adam is going to get Smaug to display some of his most extreme behaviour.
0:09:14 > 0:09:17'Not a comforting thought.'
0:09:25 > 0:09:27Well, this is Smaug.
0:09:27 > 0:09:29Waaah!
0:09:33 > 0:09:37Just look at those teeth there!
0:09:38 > 0:09:42Just in front of me here is a 15 foot crocodile!
0:09:44 > 0:09:46In this tiny little pond.
0:09:49 > 0:09:54That is properly prehistoric-looking.
0:09:54 > 0:09:58Just the size of those teeth is extraordinary.
0:10:00 > 0:10:03Look at him staring at me!
0:10:03 > 0:10:05It's actually quite unnerving.
0:10:07 > 0:10:10'While I'm inches from his jaws,
0:10:10 > 0:10:15'Adam's going to show us just how fast Smaug can react.'
0:10:15 > 0:10:17So what we're going to do is...
0:10:17 > 0:10:19a surface disturbance test.
0:10:19 > 0:10:23Basically, I'm going to throw this stone in the water, next to his head.
0:10:23 > 0:10:25It sounds a bit more impressive like that.
0:10:25 > 0:10:27And what crocodiles have got is
0:10:27 > 0:10:29all these sensory organs around their jaws.
0:10:29 > 0:10:33And they pick up pressure changes, particularly pressure changes at the surface.
0:10:33 > 0:10:37So if you're a wallaby and you're coming down and taking a drink of water,
0:10:37 > 0:10:39soon as your lips break the water,
0:10:39 > 0:10:41it's going to fire those receptors off,
0:10:41 > 0:10:44and the instinctive response is going to be to launch and grab.
0:10:44 > 0:10:46And what I'm then going to do is
0:10:46 > 0:10:49I'll throw this, and he'll expect something to hit the water.
0:10:49 > 0:10:52And soon as he does, you'll see him strike.
0:10:52 > 0:10:57- Should be an interesting experience. - Stuff that I would never see in the wild.
0:10:57 > 0:10:59Not the kind of thing you want to see...
0:10:59 > 0:11:01Want to see in the wild!
0:11:07 > 0:11:09There we go.
0:11:12 > 0:11:14Wow!
0:11:14 > 0:11:16That is incredible!
0:11:28 > 0:11:29So that's Smaug.
0:11:29 > 0:11:33That's a bit different to Botswana, isn't it?
0:11:33 > 0:11:35Yeah, that's Smaug at full speed.
0:11:35 > 0:11:37He's huge!
0:11:37 > 0:11:39That is like a dinosaur's head.
0:11:39 > 0:11:44I'm hoping that this doesn't put you off the idea of trying to dive with these animals in the wild.
0:11:44 > 0:11:47- Maybe we'll go for a slightly smaller crocodile?- Yes.
0:11:47 > 0:11:49This is not to be taken lightly, any of this.
0:11:49 > 0:11:51And the whole idea of doing this...
0:11:51 > 0:11:54I mean, I know how he reacts here.
0:11:54 > 0:11:56So we do have to be extremely careful.
0:11:58 > 0:12:00'Smaug gets rewarded for his demonstration
0:12:00 > 0:12:03'with a snack.
0:12:04 > 0:12:07'One entire chicken downed in seconds!
0:12:10 > 0:12:12'It's been a good practice run,
0:12:12 > 0:12:15'but research on Smaug in this artificial environment
0:12:15 > 0:12:17'can only tell us so much.
0:12:17 > 0:12:22'Our goal is to observe a crocodile underwater in the wild.
0:12:22 > 0:12:26'Brad will now search for a diving location with clear visibility...
0:12:26 > 0:12:28'and lots of crocodiles.
0:12:35 > 0:12:37'I also hit the road.
0:12:39 > 0:12:42'I want to investigate exactly what the explosion in crocodile numbers
0:12:42 > 0:12:45'means to the local population.
0:12:46 > 0:12:49'Many Darwin residents favour a mass cull.'
0:12:53 > 0:12:54Morning, guys.
0:12:54 > 0:12:56'On my way out of town, I meet fishermen
0:12:56 > 0:13:00'who've had terrifying experiences with crocodiles.'
0:13:00 > 0:13:02I mean, crocodiles are sneaky things.
0:13:02 > 0:13:04Worst thing I would say,
0:13:04 > 0:13:07for every one that you see, there's 20 you don't.
0:13:08 > 0:13:11I got followed out of the water at Buffalo Creek once.
0:13:11 > 0:13:14I had two, three minutes to think about life, the universe and everything.
0:13:14 > 0:13:17But yeah, I thought I was going to die that day.
0:13:17 > 0:13:19Every time I turned around, it was there.
0:13:24 > 0:13:26'Later that day, I meet up with Adam,
0:13:26 > 0:13:29'240 kilometres east of Darwin
0:13:29 > 0:13:31'in Kakadu National Park.
0:13:31 > 0:13:33'Kakadu is another area
0:13:33 > 0:13:36'where crocodiles and humans regularly collide.'
0:13:38 > 0:13:40So, where are we now, Adam?
0:13:40 > 0:13:42This is the East Alligator River.
0:13:42 > 0:13:45And this is the eastern boundary of Kakadu National Park.
0:13:45 > 0:13:49So it ends right over there, at the low water mark.
0:13:49 > 0:13:50And then, just behind you,
0:13:50 > 0:13:54you've got a crossing, and it's called Cow's Crossing.
0:13:54 > 0:13:56And why do crocodiles choose to congregate here?
0:13:56 > 0:14:00The crocodiles are here for the same reason that these guys fishing are here.
0:14:00 > 0:14:04There's a lot of fish, and they're quite easy to catch.
0:14:04 > 0:14:06You'll see a lot of them,
0:14:06 > 0:14:09they actually hold their arms out, like that, as they're swimming.
0:14:09 > 0:14:13And if a fish actually swims into this area,
0:14:13 > 0:14:16if it gets close to their jaws and touches their jaws,
0:14:16 > 0:14:18then they can detect the pressure and grab it.
0:14:18 > 0:14:21And also, if it hits either of their arms here, again,
0:14:21 > 0:14:24they can snap over and grab it.
0:14:24 > 0:14:28So they've got quite an amazing fishing net technique that they're using.
0:14:34 > 0:14:39And it's actually quite an infamous place because someone was killed here by a crocodile,
0:14:39 > 0:14:42and, as you can see behind us, there's a lot of crocodiles here.
0:14:42 > 0:14:45And what's known about that attack?
0:14:45 > 0:14:48Well, he was trying to cross the river at the crossing.
0:14:48 > 0:14:50But the water was very deep,
0:14:50 > 0:14:52and when he was going across the river,
0:14:52 > 0:14:54and this crocodile cruised up behind him,
0:14:54 > 0:14:56grabbed him on the head and pulled him under.
0:14:56 > 0:14:59So it was quite a shocking attack, actually.
0:15:01 > 0:15:03'Despite the fatal attack,
0:15:03 > 0:15:05'fishermen here ignore the warning signs.
0:15:12 > 0:15:14'And with so many people coming to the river,
0:15:14 > 0:15:17'the crocodiles are losing their fear of boats...
0:15:17 > 0:15:18'and man.
0:15:24 > 0:15:27'Heading further into Kakadu National Park,
0:15:27 > 0:15:31'I'm soon to witness yet more evidence of the increasing conflict
0:15:31 > 0:15:33'between humans and crocodiles.'
0:15:34 > 0:15:37Just had a radio call from Adam,
0:15:37 > 0:15:39who's somewhere up ahead,
0:15:39 > 0:15:43and he's with a park ranger called Gary
0:15:43 > 0:15:45who has something to show us.
0:15:53 > 0:15:56- Hi, Gary.- How're you going? Pleased to meet you again.
0:15:56 > 0:15:59- Hi there, I'm Ben.- How're you going, Ben? Gary.- Good to see you.
0:15:59 > 0:16:01This is the crocodile.
0:16:02 > 0:16:05We had a call out yesterday to a dead animal
0:16:05 > 0:16:08about 120Ks north of here.
0:16:08 > 0:16:10The most senior traditional owner there was...
0:16:10 > 0:16:13concerned about the death of a big croc.
0:16:13 > 0:16:15She's absolutely furious about it.
0:16:15 > 0:16:19Basically, some person's just shot it at the crossing there.
0:16:19 > 0:16:20- Shot it?- Yeah.
0:16:20 > 0:16:23You can see the bullet hole, just in front of the eyes here.
0:16:25 > 0:16:27It's an absolute tragedy when that occurs to one of these
0:16:27 > 0:16:30really big, important boss crocs.
0:16:31 > 0:16:33'Judging from the size of its head,
0:16:33 > 0:16:35'this crocodile must have been enormous,
0:16:35 > 0:16:38'even longer than our Jeep.'
0:16:38 > 0:16:40You're really sad about this?
0:16:40 > 0:16:43Oh, yeah. Crocs are special, but really big crocs are unique.
0:16:43 > 0:16:45They well and truly earn their right to be boss croc.
0:16:45 > 0:16:49I mean, a high percentage of crocs don't even make it to six foot.
0:16:49 > 0:16:52So, for an animal to get to 5.1 metres,
0:16:52 > 0:16:55and then be dominant in an area for years, decades,
0:16:55 > 0:16:59you well and truly earn your right to be boss croc.
0:16:59 > 0:17:02So it's a very sobering reminder...
0:17:02 > 0:17:04of just how some people feel about crocodiles.
0:17:12 > 0:17:15'It's a shocking sight.
0:17:15 > 0:17:17'This crocodile's home was very remote,
0:17:17 > 0:17:19'miles from a populated area.
0:17:20 > 0:17:23'This is a killing fuelled by real hatred.
0:17:26 > 0:17:30'But not everyone feels this way about these animals.
0:17:30 > 0:17:34'Kakadu National Park is Aboriginal land,
0:17:34 > 0:17:39'where man and croc have lived side by side for 40,000 years.
0:17:39 > 0:17:42'Here, the crocodile's role as the top predator is respected,
0:17:42 > 0:17:44'rather than resented.
0:17:49 > 0:17:51'I meet Auntie Goldie,
0:17:51 > 0:17:54'the owner of the land where the large crocodile was shot,
0:17:54 > 0:17:58'and Kakadu Park ranger, Jonathan Nadji.'
0:17:58 > 0:18:01The crocodile that Gary found, you know that individual crocodile?
0:18:01 > 0:18:04Yes, yes. I knew that he was there.
0:18:06 > 0:18:08I just...
0:18:08 > 0:18:12feel angry because I knew he was there...
0:18:12 > 0:18:14protecting an area.
0:18:17 > 0:18:19Sorry.
0:18:19 > 0:18:22It's a bit... upsetting at the moment, yeah.
0:18:30 > 0:18:34What Mum's saying is that that animal, basically, she knew it,
0:18:34 > 0:18:35and every time she went to that area,
0:18:35 > 0:18:40she would yell out to the animal and it would come, so she had a special bonding with the crocodile.
0:18:40 > 0:18:43To us, that sort of thing is just like, yeah...
0:18:43 > 0:18:45old people. Stuff like that.
0:18:47 > 0:18:48..Our family.
0:18:48 > 0:18:50Like, he'd been there, protecting that area,
0:18:50 > 0:18:52and...
0:18:52 > 0:18:54we respected it.
0:18:54 > 0:18:56He respected us.
0:18:56 > 0:19:00There seems to be a conflict between some people and crocodiles,
0:19:00 > 0:19:02with human habitation and crocodiles.
0:19:02 > 0:19:07But I gather that people can live in harmony with crocodiles.
0:19:07 > 0:19:09There's no reason why they can't.
0:19:09 > 0:19:12We do. We do. But there's other people that can't respect that law.
0:19:14 > 0:19:16We just leave them alone.
0:19:16 > 0:19:18They respect you.
0:19:18 > 0:19:20And they quietly swim away.
0:19:23 > 0:19:25'I'm moved by Auntie's distress.
0:19:25 > 0:19:29'It's remarkable how attached people can become to a crocodile.
0:19:34 > 0:19:37'The rangers in Kakadu may admire crocodiles,
0:19:37 > 0:19:40'but they still have to deal with problem animals.
0:19:45 > 0:19:48'That night, I joined Gary on patrol.
0:19:48 > 0:19:50'Rather than shooting problem crocs,
0:19:50 > 0:19:53'he's attempting a more humane approach.'
0:19:54 > 0:19:55So, Gary,
0:19:55 > 0:19:57what's the plan, how do you do this?
0:19:57 > 0:19:59What we want to do tonight is
0:19:59 > 0:20:03identifying potential problem crocs...
0:20:03 > 0:20:05that may be hanging around the boat ramp.
0:20:05 > 0:20:09And some of these crocs get quite habituated to fishing activity,
0:20:09 > 0:20:13and they associate fishermen with an easy handout feed.
0:20:13 > 0:20:15'Gary's aim is to find and scare the animal.
0:20:15 > 0:20:18'It's his very own aversion therapy.
0:20:18 > 0:20:20'But first, we need to catch it.'
0:20:20 > 0:20:23- So, how do you catch a croc? - We get right up on the animal.
0:20:23 > 0:20:25Within, you know, two or three metres.
0:20:25 > 0:20:27And then we put a harpoon...
0:20:27 > 0:20:30we just put that behind the neck, under the skin.
0:20:30 > 0:20:34It's unpleasant, but it's not too dangerous for the crocodile to have that on its skin....
0:20:34 > 0:20:36- No, it's...- It's got thick skin.
0:20:36 > 0:20:39A crocodile, what he experiences in his lifetime,
0:20:39 > 0:20:40this is pretty insignificant.
0:20:45 > 0:20:48'I'm on croc spotting duty...
0:20:48 > 0:20:51'looking out for movement in the water.'
0:20:53 > 0:20:55- There's one.- Oh, yeah.
0:20:55 > 0:20:58Keep going, keep going, keep going, keep going, keep going.
0:20:58 > 0:21:00Keep going.
0:21:02 > 0:21:04Neutral, neutral, neutral.
0:21:05 > 0:21:06'We missed him,
0:21:06 > 0:21:09'but quickly pick up his trail again.'
0:21:09 > 0:21:10Bubbles there?
0:21:10 > 0:21:13- There were some bubbles as it popped down.- You see the bubbles?- Yep.
0:21:21 > 0:21:23That's going to go. Yep, got him.
0:21:23 > 0:21:26When he comes up, Ben, bright light just goes straight on his eyes.
0:21:26 > 0:21:28Straight on his eyes, OK.
0:21:28 > 0:21:30This is crazy.
0:21:30 > 0:21:34Amazing! Can't believe they've got a...
0:21:34 > 0:21:37two-metre croc on the end of that line!
0:21:47 > 0:21:49'It looks harsh...
0:21:49 > 0:21:50'because it is.
0:21:50 > 0:21:53'But I know this rough handling is for the crocodile's own good.
0:21:53 > 0:21:56'He'd end up being shot if he attacked anyone.'
0:21:56 > 0:21:58Happy with the knot?
0:22:02 > 0:22:05Just hold him there, look.
0:22:05 > 0:22:06That'll do, yep.
0:22:06 > 0:22:10And hold him there look. The next phase is to shut his jaws,
0:22:10 > 0:22:13and once we do that, it makes handling the animal a lot easier.
0:22:13 > 0:22:17So all we're going to do is just put a zip tag around both jaws.
0:22:20 > 0:22:22This is the most dangerous part.
0:22:22 > 0:22:25It's just a matter of getting the jaws shut,
0:22:25 > 0:22:27and then we can start doing things with him.
0:22:27 > 0:22:29And we're happy with that.
0:22:29 > 0:22:34But this process now is just giving the animal a bit of a scare.
0:22:34 > 0:22:37It's probably thinking, "What the hell's happening on?"
0:22:37 > 0:22:40It's probably likely a death experience. Then we let him go.
0:22:40 > 0:22:42And, basically, this is what you want,
0:22:42 > 0:22:44make him a bit more wary of people.
0:22:45 > 0:22:47All right, when he comes inside the boat,
0:22:47 > 0:22:49just keep him really still.
0:22:49 > 0:22:51We don't want any head swing happening.
0:22:51 > 0:22:53We don't want him to damage himself too much.
0:22:53 > 0:22:56Exactly. But, more importantly, don't want him damaging us.
0:22:56 > 0:22:58- OK.- All right. Let's go.
0:23:00 > 0:23:02All right, let's go.
0:23:04 > 0:23:05Straight down.
0:23:07 > 0:23:08OK.
0:23:08 > 0:23:09On the head. Give us this body.
0:23:09 > 0:23:11Push down on the head hard. Both hands.
0:23:11 > 0:23:14OK. Yep.
0:23:14 > 0:23:16Now push down on the snout.
0:23:16 > 0:23:19Back to the boat ramp, driver.
0:23:42 > 0:23:45He's quite heavy, isn't he? Where are we going?
0:23:45 > 0:23:48All right, now come down, Jonno.
0:23:48 > 0:23:51What we're going to do is we're going to secure him first
0:23:51 > 0:23:52to this pole, right here.
0:23:52 > 0:23:55OK, now put it round, same we did the other day.
0:23:55 > 0:23:58And what we want to do is just secure his head
0:23:58 > 0:24:00cos he's really going to think.
0:24:00 > 0:24:01Right, when he goes down...
0:24:01 > 0:24:02pull up.
0:24:03 > 0:24:05Now, bring his...
0:24:05 > 0:24:08That's it, tie him tight.
0:24:08 > 0:24:09That's it.
0:24:09 > 0:24:10Very good.
0:24:10 > 0:24:14OK. Now, roll him towards the...
0:24:14 > 0:24:16cos I want to see his underbelly.
0:24:16 > 0:24:18- Like that?- That's it.
0:24:18 > 0:24:21'The final part of the process is sexing the crocodile
0:24:21 > 0:24:23'to determine its gender.
0:24:23 > 0:24:25'This is probably uncomfortable for him, too.'
0:24:25 > 0:24:27- Finger in there, Ben.- Yep.
0:24:27 > 0:24:29Right in there, and just tell me what sex it is.
0:24:29 > 0:24:31What am I feeling for?
0:24:31 > 0:24:33Harder. You'll be feeling it yet.
0:24:33 > 0:24:35Bit more. Long and hard?
0:24:35 > 0:24:36- Yep.- What do you reckon?
0:24:36 > 0:24:38Male?
0:24:39 > 0:24:42Wow. So I've just sexed a crocodile.
0:24:44 > 0:24:46It's just incredible, cos this...
0:24:46 > 0:24:50is as close as I'm ever going to get to a dinosaur.
0:24:50 > 0:24:53So I just want to have a look at every single part of it
0:24:53 > 0:24:56cos it is a fascinating, incredible creature.
0:24:56 > 0:24:59'These are beautiful animals.
0:24:59 > 0:25:03'Their massive webbed feet are used for steering and walking underwater.
0:25:03 > 0:25:06'And their 66 teeth are constantly replaced.
0:25:06 > 0:25:09'They get through 3,000 in their lives.'
0:25:11 > 0:25:13So we're ready to release him?
0:25:13 > 0:25:17Yep. This is probably just as dangerous as tying their jaws up.
0:25:17 > 0:25:19Just keep him firm there,
0:25:19 > 0:25:23and just keep his legs pulled back along his tail.
0:25:23 > 0:25:26He's starting to get... Ooh!
0:25:26 > 0:25:28All right, hold him. Just tight, tight.
0:25:28 > 0:25:29Yep. Waah!
0:25:29 > 0:25:33- You can feel the power there? - Yeah, that's quite a lot of power.
0:25:33 > 0:25:35- Sit on him.- OK, like that? - That's it.
0:25:35 > 0:25:36Wow.
0:25:36 > 0:25:38That was more powerful than I am!
0:25:38 > 0:25:42When something like this grabs you in the water, people think it's a small croc.
0:25:42 > 0:25:46If it grabs you in the water, you've got no hope. At the water's edge, the same.
0:25:46 > 0:25:48That would have flipped me over just then.
0:25:48 > 0:25:50Especially when it's got a limb or a leg,
0:25:50 > 0:25:53it'll do a succession of quick rolls.
0:25:53 > 0:25:54Mmm-hmm.
0:25:54 > 0:25:56And basically, dislocate or break your leg...
0:25:56 > 0:25:58or your arm.
0:25:58 > 0:26:00Maybe I'll just undo this one first.
0:26:04 > 0:26:06OK, you start walking.
0:26:06 > 0:26:07Yep.
0:26:07 > 0:26:09Go walk straight back up.
0:26:09 > 0:26:11Just go where Ralph is, on your right.
0:26:11 > 0:26:12'He doesn't sound happy.
0:26:12 > 0:26:14'Having been tied up for so long,
0:26:14 > 0:26:16'anything could happen.'
0:26:20 > 0:26:22Back, back, back, back, back.
0:26:22 > 0:26:24Keep coming! Back, back.
0:26:29 > 0:26:30Slide, slide.
0:26:32 > 0:26:34'Unluckily for this crocodile,
0:26:34 > 0:26:36'the water's in the opposite direction.
0:26:36 > 0:26:38Come on, here.
0:26:38 > 0:26:41That was an angry croc, but that's the point, I suppose.
0:26:41 > 0:26:42Here!
0:26:53 > 0:26:54'He finally gets his bearings
0:26:54 > 0:26:56'and makes it back to the river.'
0:27:06 > 0:27:09That's just a very surreal night, really.
0:27:09 > 0:27:11This whole thing's been very surreal.
0:27:11 > 0:27:14But, naturally, the crocodile...
0:27:14 > 0:27:17went mental when it was released.
0:27:17 > 0:27:21And what I thought was fascinating is of all the people that were here -
0:27:21 > 0:27:24cos a few people have turned up, there's police, everything's here -
0:27:24 > 0:27:26it went for Gary.
0:27:26 > 0:27:28Which means it seemed to have worked.
0:27:30 > 0:27:32'Hopefully, that crocodile won't risk approaching
0:27:32 > 0:27:35'people or boats again.
0:27:35 > 0:27:37'But the problem is too widespread
0:27:37 > 0:27:39'for this approach to work everywhere.'
0:27:41 > 0:27:43Do you think there's a slight problem
0:27:43 > 0:27:45that not enough people realise
0:27:45 > 0:27:50or respect the dangers of crocodiles?
0:27:50 > 0:27:52When people are coming,
0:27:52 > 0:27:56and if they're thinking that the waterway's solely for them,
0:27:56 > 0:27:58I think that's a really sort of ...
0:27:59 > 0:28:01..greedy, selfish attitude.
0:28:01 > 0:28:05This is Aboriginal land, first and foremost.
0:28:05 > 0:28:06Consider yourself a guest,
0:28:06 > 0:28:09understand that crocs are there
0:28:09 > 0:28:11and just be safe.
0:28:11 > 0:28:15And have a lot of respect. Don't sort of think it's all yours.
0:28:23 > 0:28:27'Today, I'm rejoining our underwater research team.
0:28:27 > 0:28:31'The plan to get underwater with crocs has run into difficulties.'
0:28:31 > 0:28:33What it is,
0:28:33 > 0:28:35I left Darwin, went the whole way to the Flora River,
0:28:35 > 0:28:39which is meant to be...20 metres visibility this time of year.
0:28:39 > 0:28:42It's THE clearest river in the Northern Territory.
0:28:42 > 0:28:46- And now?- Not the clearest river in the Northern Territory!
0:28:46 > 0:28:47Probably three, four metres at most.
0:28:47 > 0:28:49Really? What are all the rivers so bad?
0:28:49 > 0:28:52Well, we had a record wet season this year. So much rain,
0:28:52 > 0:28:55and it brings all kinds of silt and sediment down with it.
0:28:55 > 0:28:59- And is there anything suitable that you found?- Nothing. Nothing suitable.
0:28:59 > 0:29:03I mean, nothing that we could consider diving...
0:29:03 > 0:29:07- with salties on. - So what's the next best option?
0:29:07 > 0:29:09I mean, the other possibility
0:29:09 > 0:29:11is up here, on the Cobourg Peninsula.
0:29:11 > 0:29:15There's actually been a few crocodile attacks here.
0:29:15 > 0:29:18- That means there are saltwater crocs up there.- There definitely are.
0:29:18 > 0:29:21- And big enough to eat you. - And hopefully clear water?
0:29:21 > 0:29:24Yeah. If we find crocodiles, clear water and the conditions are right,
0:29:24 > 0:29:28and we've got luck on our side, then maybe we'll find the right conditions.
0:29:28 > 0:29:31Oh, I'm getting all excited! This could be cool.
0:29:36 > 0:29:39'So, we're travelling 320 kilometres north of Darwin
0:29:39 > 0:29:41'into a very remote area.
0:29:41 > 0:29:45'We now have just a few days left to find clear water
0:29:45 > 0:29:47'and attempt our pioneering dive with salties.'
0:29:51 > 0:29:52OK, another adventure.
0:29:52 > 0:29:54Oh, off again.
0:29:56 > 0:30:00'We've pinpointed what could be a perfect diving location.
0:30:00 > 0:30:03'But the wild crocodiles there are an unknown quantity.
0:30:03 > 0:30:07'Most people avoid the waters of the Cobourg Peninsula.'
0:30:08 > 0:30:11It's a bit scary because we are entering an area
0:30:11 > 0:30:15with the most dangerous marine life in the world -
0:30:15 > 0:30:20box jellyfish, sea snakes, various sharks.
0:30:20 > 0:30:24So we're kind of upping the danger, but, you know,
0:30:24 > 0:30:27the potential for having an encounter is increased,
0:30:27 > 0:30:31so I really don't know what's going to happen here.
0:30:40 > 0:30:43'After touching down late afternoon, we head straight out to the coast
0:30:43 > 0:30:46'to look for signs of crocodile activity.
0:30:52 > 0:30:56'These beaches look perfect for sunbathing
0:30:56 > 0:30:59'and Adam tells me that crocodiles bask here
0:30:59 > 0:31:00'in much the same way.'
0:31:08 > 0:31:11- Hey, guys?- Yeah?- Is that one there?
0:31:11 > 0:31:15- Oh, yeah.- Cruising across the middle.- Is that it?
0:31:17 > 0:31:20So what sort of size do you think that one is?
0:31:20 > 0:31:22Probably over three metres.
0:31:22 > 0:31:26- What do you think it's doing now? - Well, he's actually moving away.
0:31:26 > 0:31:30He may have actually been on the beach. And he's now heading out.
0:31:30 > 0:31:32He may have heard us coming down that hill.
0:31:32 > 0:31:36And he's slowly heading out across there. He looks like he's heading into deeper water.
0:31:36 > 0:31:40Yeah. Could we go out, in a boat now, and jump in the water there?
0:31:40 > 0:31:43I don't think it's got the right sort of topography.
0:31:43 > 0:31:48If we had to find them out there, if we got in the water he'd move, or he'd move away from the boat.
0:31:48 > 0:31:51If you pick them up on big open flats like this,
0:31:51 > 0:31:55they'll move quite quickly. It's going to be very difficult to actually get in the water.
0:31:59 > 0:32:04'If it's not possible to control a dive with crocodiles swimming out at sea, then tomorrow
0:32:04 > 0:32:08'we'll have to hunt for them in enclosed waterways.
0:32:17 > 0:32:21'Our plan is to scour the creeks of the Cobourg Peninsula.'
0:32:21 > 0:32:23Excited?
0:32:23 > 0:32:27'Time is running out and we're determined to attempt our wild dive.'
0:32:27 > 0:32:29What do you think our chances are?
0:32:29 > 0:32:31If we get visibility, pretty good eh?
0:32:31 > 0:32:33- Yeah?- Yeah, I'm dying to get some clean water.
0:32:33 > 0:32:36- That's really the thing that we're hinging on.- Yeah.
0:32:38 > 0:32:40'We're entering very dangerous waters,
0:32:40 > 0:32:43'and are joined by safety divers and medics.'
0:32:43 > 0:32:45OK, I'm ready to let go here.
0:32:48 > 0:32:52'We're looking for a croc less than two metres long.
0:32:52 > 0:32:54'From Brad's African experience,
0:32:54 > 0:32:57'crocodiles are unlikely to attack anything bigger than themselves.'
0:32:59 > 0:33:02There's a few things on the beach there, that could maybe be crocodiles.
0:33:02 > 0:33:06It's about the sort of time that you'd expect them to be basking.
0:33:07 > 0:33:10You see it here? It's right in front of us.
0:33:10 > 0:33:13- Yeah, it's a croc, eh?- It's a croc? - It's a bloody croc.- Right there?
0:33:13 > 0:33:16- Is it? Is it a croc?- Yeah.- Yeah.
0:33:16 > 0:33:19- Yeah, that's a croc for sure, eh? - Here, here, here, here.
0:33:19 > 0:33:21I think it's just here.
0:33:22 > 0:33:27That's unbelievable. We've seen a crocodile here already. Woah, I don't want to fall in this now.
0:33:27 > 0:33:28Not without my spike.
0:33:30 > 0:33:33'The shallow waters in these bays are teeming with life,
0:33:33 > 0:33:38'much of which, as our Australian camera crew remind us, is deadly.
0:33:38 > 0:33:43You have to wear shoes or wet-suit boots because this is stonefish country.
0:33:43 > 0:33:48- Am I OK in flip-flops? - They're very, very dangerous.
0:33:48 > 0:33:53Don't pick up any shells or anything, they could be cone shells - they'll kill you.
0:33:53 > 0:33:56You could get stung by a box jellyfish, that will kill you too.
0:33:56 > 0:34:00Watch out for sea snakes, OK? And, of course, there's crocodiles.
0:34:00 > 0:34:02You've already seen one. So...
0:34:02 > 0:34:06Otherwise there's nothing much to be concerned about.
0:34:06 > 0:34:08That's reassuring(!)
0:34:18 > 0:34:22'We're entering a clear, saltwater creek.
0:34:22 > 0:34:24'Unlike the areas I've already visited,
0:34:24 > 0:34:27'the crocodiles have rarely, if ever, seen a human here.'
0:34:29 > 0:34:31So we just need to keep the voices down
0:34:31 > 0:34:35so that if we see a crocodile, it doesn't hear us coming first.
0:34:40 > 0:34:42'The water in these creeks is tidal,
0:34:42 > 0:34:45'and only deep enough for us to dive in for five hours.
0:34:45 > 0:34:50'We have to leave before the water levels drop or we'll be stranded.'
0:34:57 > 0:35:00'Time is against us.
0:35:00 > 0:35:05'But we finally see a hopeful sign - a clear crocodile track.'
0:35:05 > 0:35:09- Wait.- Don't take too many folk out for the footprints, keep them clean.
0:35:09 > 0:35:13These look actually like the scales on the underside of the tail.
0:35:13 > 0:35:17- So the crocodile's actually swung his tail around.- Mm-hm.
0:35:17 > 0:35:20So we know there's a croc around. We've seen a croc.
0:35:20 > 0:35:22It's just a matter of finding him
0:35:22 > 0:35:24and the right vis at the right depth.
0:35:24 > 0:35:26- Yeah. - Shall we try back in the creek?
0:35:26 > 0:35:29- Do you think the tide might be... - Let's go round that creek again.
0:35:29 > 0:35:32'It's the track of a fairly small crocodile -
0:35:32 > 0:35:35'the perfect animal for our first dive.'
0:35:39 > 0:35:44'Spooked by our approach, it could be hiding in the water below.'
0:35:44 > 0:35:46We can't see them from the surface,
0:35:46 > 0:35:50we'll just have to go and have a look for him underwater.
0:35:52 > 0:35:54'Brad's croc-diving method, developed in Botswana,
0:35:54 > 0:35:59'is to get into deep water as quickly as possible.
0:35:59 > 0:36:01'Crocodiles mostly attack at the surface
0:36:01 > 0:36:04'and are less likely to see us as prey underwater.
0:36:04 > 0:36:07'While the waters are still deep enough to dive,
0:36:07 > 0:36:10'this could be the chance we've been waiting for -
0:36:10 > 0:36:12'to see a saltie's underwater behaviour.'
0:36:27 > 0:36:28'In these unknown waters,
0:36:28 > 0:36:32'only the most experienced divers head into the mangroves...
0:36:33 > 0:36:36..'while I keep track of their movements from the boat.'
0:36:38 > 0:36:41They've all got their croc spikes and we have to follow
0:36:41 > 0:36:44exactly the same routine that we've always done.
0:36:46 > 0:36:50'The team stick together and slowly enter the mangroves.
0:36:59 > 0:37:01'The crocodile could be anywhere.
0:37:01 > 0:37:06'In the underwater gloom, it's not proving easy to find.'
0:37:17 > 0:37:21Obviously the difficulty that we have here is that we're in a mangrove swamp.
0:37:21 > 0:37:24But if you just look over there, that's open water.
0:37:24 > 0:37:29We've got this huge, vast area that the crocodiles can escape to
0:37:29 > 0:37:32and we've already seen them out in the sea.
0:37:32 > 0:37:36So it's very difficult to pinpoint them to one area,
0:37:36 > 0:37:38it's a vast expanse.
0:37:39 > 0:37:43'In a break from protocol, the team spread out.
0:37:43 > 0:37:46'But still there's no sign of the crocodile.
0:37:47 > 0:37:50'And, as the tide goes out and water levels fall,
0:37:50 > 0:37:52'we're forced to abandon the dive.'
0:37:58 > 0:38:00Get this forward.
0:38:02 > 0:38:06Pity that there was no contacts for the study.
0:38:06 > 0:38:08Yeah.
0:38:10 > 0:38:13'We've been defeated by the conditions.
0:38:13 > 0:38:16'It's a huge disappointment.
0:38:16 > 0:38:20'With today's diving window well and truly closed, we head for home.'
0:38:26 > 0:38:29- Here it is, here it is.- Here he is.
0:38:29 > 0:38:31- Right next to us.- Wow.
0:38:32 > 0:38:36- Did he hear that, do you think? Or it spotted us?- Yes. He would have heard that.
0:38:36 > 0:38:40It's like this whole thing is like it's so tantalising.
0:38:40 > 0:38:44- We've gotten so close with this. - Teasing us.
0:38:44 > 0:38:46- We have to remember... - Plenty of clear water.
0:38:46 > 0:38:49But we have to remember we are dealing with wild crocodiles,
0:38:49 > 0:38:52that's the thing, and it's just pushing it a little bit too far.
0:38:55 > 0:38:58'We've got just two more days together in Australia.
0:38:58 > 0:39:02'The conditions in Cobourg are too challenging to conquer in our time frame.
0:39:06 > 0:39:10'But a small opportunity has opened up back in Darwin.
0:39:10 > 0:39:12'This morning, Adam got a call.
0:39:12 > 0:39:16'A male saltwater croc has been caught trying to get into Darwin harbour.'
0:39:17 > 0:39:22They do actually have a crocodile that the rangers have pulled out of the harbour.
0:39:22 > 0:39:27It is possible for us to actually dive with that crocodile under controlled conditions
0:39:27 > 0:39:30and so we can actually go in there and we can see
0:39:30 > 0:39:33whether the animal behaves in a way that we'd expect it to.
0:39:33 > 0:39:37- I'm in.- I'm in. - It's the next best thing.
0:39:37 > 0:39:42- I mean, just to get that experience will be worthwhile.- OK.
0:39:43 > 0:39:47'We can place this crocodile into a clear water billabong.
0:39:47 > 0:39:49'The crocodile won't be in its own territory,
0:39:49 > 0:39:53'but it will give us the chance to try and dive with a saltwater croc in the wild.
0:39:53 > 0:39:58'We head back to the city, where, in a holding pen,
0:39:58 > 0:40:02'there's a wild, angry, three-metre-long crocodile.
0:40:07 > 0:40:09'A problem crocodile caught in the harbour
0:40:09 > 0:40:13'is usually dispatched to a croc farm to be killed.
0:40:13 > 0:40:16'We've arranged a temporary stay of execution
0:40:16 > 0:40:18'for us to attempt our underwater research.
0:40:20 > 0:40:26'But first we've got to get one fiery reptile back into the water.'
0:40:26 > 0:40:30Come on. Open your mouth. Come on, bit further. Bit more.
0:40:30 > 0:40:32Here it comes. Whoop.
0:40:32 > 0:40:33Here we go.
0:40:41 > 0:40:45Come on. OK. So we're going to need to pull him up into this area here.
0:40:45 > 0:40:49This is the danger zone. So if you're there, just make sure you've got an escape route.
0:40:49 > 0:40:53- Going to start rolling. - Winding himself up.- Yeah.
0:40:53 > 0:40:57Got to be careful he doesn't... I don't want him to injure himself on the...
0:41:00 > 0:41:02- Do you want to do the honours? - Yeah, all right.
0:41:02 > 0:41:06- OK, you want to get it down? Get it underneath his lower jaw.- Yeah.
0:41:06 > 0:41:10Wait, I'll lift his jaw. Hold on, let me do it.
0:41:11 > 0:41:15Let me just get the tip of his jaw. Hold on, wait a sec.
0:41:19 > 0:41:25That looks better. Woah! That's good. Keep going on that one, big girl.
0:41:33 > 0:41:38- OK, get him out now. Now that he's tied up nicely.- Yeah.
0:41:38 > 0:41:43Pull him out here. Let's get him out. Slide it off, OK, are you ready?
0:41:43 > 0:41:46Now, bit forward in front of his front legs now.
0:41:46 > 0:41:50Front of his back legs, sorry.
0:41:50 > 0:41:53We have to be nice and calm.
0:41:53 > 0:41:58- OK, now, Brendan, go. - Push down. Press down, down.
0:41:58 > 0:42:01'The crocodile rolls to avoid capture.
0:42:01 > 0:42:05'This is also how crocs spin to rip flesh off its victims
0:42:05 > 0:42:06'in a death roll.'
0:42:06 > 0:42:07Ready? One, two, up.
0:42:07 > 0:42:10GRUNTS OK.
0:42:14 > 0:42:19- Oh, he's a bit heavier than the usual croc I get in here.- Quickly.- OK.
0:42:20 > 0:42:24- There we go.- That's it. Good job, guys.
0:42:33 > 0:42:36'Our diving location is a clear water spring.
0:42:36 > 0:42:40'It's the perfect site for us to release our crocodile for a short time.
0:42:41 > 0:42:45'We know so little about the underwater world of crocodiles
0:42:45 > 0:42:48'that any new information about these ancient predators
0:42:48 > 0:42:52'can only help the conflict between people and crocs.'
0:42:52 > 0:42:55That's fine. Put that on afterwards.
0:42:55 > 0:42:58'Brad's dived with crocs in Africa for five years.'
0:42:59 > 0:43:01I'm happy with it.
0:43:01 > 0:43:03'He knows how Nile crocodiles react,
0:43:03 > 0:43:06'but diving with a saltie is virgin territory.'
0:43:06 > 0:43:10Really it's about learning their behaviour.
0:43:10 > 0:43:11See how they react to divers
0:43:11 > 0:43:14and the presence of a person underwater.
0:43:14 > 0:43:17That's the most important thing and this is just a small window
0:43:17 > 0:43:21that we can learn from, and it's, I think, one that has to be taken.
0:43:23 > 0:43:24I'm really excited.
0:43:24 > 0:43:29I came out here to dive and, yeah, I'm really looking forward to getting in.
0:43:29 > 0:43:32'To transport the crocodile and get it into the spring,
0:43:32 > 0:43:34'we've put a temporary safety measure in place.'
0:43:34 > 0:43:38I mean, obviously you know that there's a little bit of fishing line
0:43:38 > 0:43:42that you've got taped around the crocodile's jaws,
0:43:42 > 0:43:46but if you get really close to that crocodile, simply the power
0:43:46 > 0:43:49that the animal has in his neck muscles, and the weight of the head -
0:43:49 > 0:43:54which is pretty much solid bone - it's still very capable of inflicting a huge amount of damage.
0:43:54 > 0:43:57There's still tension that you have in the water around it.
0:43:59 > 0:44:03'And, at some point, the nylon line WILL come off.
0:44:08 > 0:44:12'We need to quickly get away from the kill zone at the surface
0:44:12 > 0:44:14'and into deep water.
0:44:19 > 0:44:24'We stick together and, very cautiously, set off in search of the crocodile.
0:44:31 > 0:44:34'We have one very clear objective, to find out
0:44:34 > 0:44:37'if the crocodile will allow us to approach.
0:44:37 > 0:44:43'If so, then future wild underwater research is a very real possibility.'
0:44:45 > 0:44:50So I'm just going to stay outside of his attack range.
0:44:50 > 0:44:54And I'm pretty sure that he can see me.
0:44:57 > 0:45:02'Normally the attack zone is half the length of the crocodile's body.
0:45:02 > 0:45:05'So, for this initial part of the dive, we keep that distance.'
0:45:08 > 0:45:13I'll just stay back a little bit. Just see what he decides to do.
0:45:16 > 0:45:20'He decides...to do nothing.
0:45:20 > 0:45:22'He seems unfazed by our presence
0:45:22 > 0:45:26'and has taken up a position basking in the underwater sunshine.'
0:45:27 > 0:45:33It's really quite something to be this close to a saltwater crocodile.
0:45:33 > 0:45:37His eyes are open, he knows I'm here...
0:45:37 > 0:45:39and is just sitting there.
0:45:42 > 0:45:45'As he moves away, we tentatively follow.'
0:45:48 > 0:45:52Just watch him coming up to the surface, very slowly.
0:45:57 > 0:46:01Take a breath of air. Look how slowly it creeps up that bank.
0:46:01 > 0:46:03Really amazing sight, that.
0:46:07 > 0:46:11This is a wild crocodile, we are in a wild billabong
0:46:11 > 0:46:15and it seems to be acting like the Nile crocodiles in Botswana.
0:46:18 > 0:46:22'We can observe how he conserves energy by walking on the river bed,
0:46:22 > 0:46:23'rather than swimming.'
0:46:31 > 0:46:35He's trying to get his bearings.
0:46:35 > 0:46:41And then, every so often, he's going up to the surface to take a breath.
0:46:41 > 0:46:46He's not staying there very long. And he's going back down again.
0:46:48 > 0:46:51And then resting again.
0:46:51 > 0:46:54'But now is the real test.
0:46:54 > 0:46:58'Will he allow us into his attack zone without striking?'
0:47:07 > 0:47:13And I'm pretty sure that he can see me. Look at that, OK.
0:47:14 > 0:47:22So this guy is completely not bothered that I'm here at all.
0:47:24 > 0:47:26'The answer is yes.'
0:47:29 > 0:47:31Just is awesome to see.
0:47:33 > 0:47:37'Brad believes that crocs see divers as other crocs in the water,
0:47:37 > 0:47:39'rather than prey.
0:47:39 > 0:47:44'Whether or not that's true, this one has absolutely no interest in attacking us.'
0:47:44 > 0:47:48So easy just to touch their tail.
0:47:51 > 0:47:54It would be so easy to take a tissue sample.
0:47:54 > 0:47:59Just reminds me again of what potentially could be done in terms of research.
0:48:02 > 0:48:04'Studying crocodiles in their underwater world,
0:48:04 > 0:48:08'revealing new information on their senses and behaviour,
0:48:08 > 0:48:13'will push the boundary of our knowledge about this extraordinary species.'
0:48:24 > 0:48:32Today, he allowed a brief glimpse into this sub-aquatic, watery world.
0:48:32 > 0:48:36I see a very different side of these predators.
0:48:36 > 0:48:40Crocodiles are often described as the ultimate killing machines,
0:48:40 > 0:48:44and they are. But, here, underwater...
0:48:47 > 0:48:50..is a very different world.
0:49:08 > 0:49:13Wow. Well, that was pretty special.
0:49:13 > 0:49:18Just amazing to kind of sit there and see it in a natural habitat.
0:49:18 > 0:49:21And I think many people have this image that it would be
0:49:21 > 0:49:25going for us and tearing around underwater, but it's actually,
0:49:25 > 0:49:28once it's underwater, it's a very placid creature.
0:49:28 > 0:49:31And I think that's what this whole journey's been about.
0:49:31 > 0:49:34It's been about discovering that crocodiles
0:49:34 > 0:49:37are very different from those creatures that we see.
0:49:37 > 0:49:41You know, 80% of a crocodile's life is underwater
0:49:41 > 0:49:43and so little is known about that.
0:49:46 > 0:49:49Well, it's quite magical, I think, to be underwater with a crocodile.
0:49:49 > 0:49:52You're getting a view that most other people would never see.
0:49:52 > 0:49:56If we can find areas where there are saltwater crocodiles,
0:49:56 > 0:49:59and there's clear water, and the conditions are right,
0:49:59 > 0:50:02then the whole world is suddenly going to open up to us
0:50:02 > 0:50:05in terms of what's possible with those animals.
0:50:08 > 0:50:12This crocodile would normally be taken away to be killed.
0:50:12 > 0:50:15But having dived with this beautiful creature,
0:50:15 > 0:50:17none of us want to see that happen.
0:50:17 > 0:50:20So we devise an alternative...
0:50:32 > 0:50:34On our final morning in Australia,
0:50:34 > 0:50:38we put our crocodile rescue plan into action.
0:50:41 > 0:50:44It's funny how things turn out.
0:50:44 > 0:50:47I haven't been able to get out of my mind that image of that...
0:50:47 > 0:50:51enormous crocodile head that was shot,
0:50:51 > 0:50:57and how distraught Auntie was
0:50:57 > 0:51:00on discovering that her favourite crocodile,
0:51:00 > 0:51:05that she referred to as her family member, had been killed.
0:51:05 > 0:51:09And then I was diving with that crocodile yesterday,
0:51:09 > 0:51:12that had been caught in the harbour,
0:51:12 > 0:51:15and again I couldn't bear the thought that
0:51:15 > 0:51:20this croc might go to the farm and be turned into
0:51:20 > 0:51:23a belt or a handbag.
0:51:23 > 0:51:26So Adam has been able to...
0:51:26 > 0:51:31sweet-talk everyone in the country
0:51:31 > 0:51:33and called Auntie, and said to her, listen,
0:51:33 > 0:51:37we've got this crocodile, could we release it on her land?
0:51:37 > 0:51:41And, unbelievably, everyone has said yes.
0:51:41 > 0:51:43So I'm now heading back up towards Cobourg
0:51:43 > 0:51:48and we're off to release one...
0:51:48 > 0:51:52that I've called Ludo. I've spent so much time with it I had to give it a name.
0:51:52 > 0:51:57Everyone called it "the crocodile that was caught in the harbour", so I've called it Ludo, after my son.
0:51:58 > 0:52:00So at this very minute,
0:52:00 > 0:52:05Ludo the crocodile is in the back of Adam's car
0:52:05 > 0:52:07with a magnet on its head.
0:52:07 > 0:52:09You couldn't make it up, could you?
0:52:11 > 0:52:13Ludo also gives us
0:52:13 > 0:52:17a great opportunity to research a crocodile's homing instincts.
0:52:17 > 0:52:19We'll see if a magnet on his head
0:52:19 > 0:52:23will temporarily confuse his magnetic sense of direction.
0:52:23 > 0:52:27Our hope is that this will stop him returning to Darwin Harbour.
0:52:27 > 0:52:30If he's caught back there, he'll be killed.
0:52:31 > 0:52:34We're going to release him a long way
0:52:34 > 0:52:36from where he was trapped,
0:52:36 > 0:52:38and use a GPS device to track his movements.
0:52:38 > 0:52:42- Hey, guys, how are you?- Hi. - Good to see you. How are you all?
0:52:42 > 0:52:43- How you going, Ben?- Really well.
0:52:43 > 0:52:49- Listen, thank you very much for doing this.- No, it should be good.
0:52:49 > 0:52:53Fantastic for you as well, to be able to actually put a tracking device on it.
0:52:53 > 0:52:57Yeah, I'm very interested to see whether he goes straight back in that direction
0:52:57 > 0:53:00or whether he looks around a bit and has no idea where he is.
0:53:00 > 0:53:04- Shall we go and get the croc out? - Yep.- I'm really excited about this.
0:53:04 > 0:53:06- He might be a bit fiery, so...- OK.
0:53:07 > 0:53:11'Auntie keeps watch over the arrival of her new crocodile.'
0:53:14 > 0:53:17- This is the magnet...- Oh, yeah.
0:53:17 > 0:53:20It's actually it's a very hi-tech piece of equipment,
0:53:20 > 0:53:23it's an old stereo car speaker from my old Honda. BEN LAUGHS
0:53:23 > 0:53:26So that's been sitting on the back of his head,
0:53:26 > 0:53:29so hopefully any ability he has to orientate using magnetic fields
0:53:29 > 0:53:31would have been completely wiped out.
0:53:31 > 0:53:34- So he'll probably think he's still back in Darwin.- Wow.
0:53:34 > 0:53:37'Crocs have almost homing pigeon-like instincts,
0:53:37 > 0:53:40'and relocated ones often find their way home.
0:53:40 > 0:53:45'We'll see if this magnet stops Ludo from heading back to Darwin Harbour.'
0:53:45 > 0:53:47- OK...- Yeah?- Yup.
0:53:54 > 0:53:57- Is this a good croc to put a GPS device on?- Yeah.
0:53:57 > 0:54:00He's the kind of animal that we want to find out a lot more
0:54:00 > 0:54:03about what's making him move, where he's going to,
0:54:03 > 0:54:05the kind of habitat he's trying to find.
0:54:05 > 0:54:08And these guys are going to be very interested in what we find out.
0:54:10 > 0:54:14- What's this one called? - This crocodile's called Ludo.
0:54:14 > 0:54:16L-U-D-O.
0:54:16 > 0:54:21Do you realise this crocodile will probably live as long, if not longer, than your son.
0:54:21 > 0:54:22That's pretty crazy, that.
0:54:22 > 0:54:26- So for his entire life he'll have a crocodile swimming around here. - That's too cool.
0:54:26 > 0:54:30'This transmitter will send out a GPS signal every hour.'
0:54:31 > 0:54:33OK. It looks good.
0:54:33 > 0:54:36It's flashing, so it's operating...
0:54:36 > 0:54:41- So this is all making it watertight, isn't it?- Yes. This will fall off eventually.
0:54:41 > 0:54:44It's not going to be here for the next 60 years.
0:54:44 > 0:54:48And hopefully in that time we'll get some really great information
0:54:48 > 0:54:52from it. And, you know, Ludo will be... He's a pioneer.
0:54:52 > 0:54:55- I smile whenever I hear that. It's brilliant.- He's a pioneer.
0:54:55 > 0:54:59Our preconceptions about crocodiles are very different to the reality.
0:54:59 > 0:55:03And this kind of thing will help to fill in the blanks.
0:55:04 > 0:55:07OK, one, two, three...
0:55:07 > 0:55:09Right up.
0:55:09 > 0:55:11- OK?- Yep.
0:55:21 > 0:55:22- Just here, eh?- Just here?
0:55:27 > 0:55:30- Can you go back a bit? - Yeah.- Hold him tight.
0:55:31 > 0:55:35- OK, drop it, Ben.- Drop it? OK.
0:55:49 > 0:55:51There he goes...
0:56:14 > 0:56:16Go on, boy...
0:56:38 > 0:56:42I'd say see you later, alligator, but we actually don't want to see him again.
0:56:42 > 0:56:45So I'll just say good luck. Bon voyage!
0:56:45 > 0:56:49Oh, look at that. He's tasting the salt water now.
0:56:56 > 0:57:01That's really cool. What an amazing experience this has all been.
0:57:01 > 0:57:06I feel so lucky to have shared the whole thing -
0:57:06 > 0:57:09right from the beginning, from my time in Botswana, you know,
0:57:09 > 0:57:12when I was terrified of the crocodiles,
0:57:12 > 0:57:15terrified about going in. I just remember the heart palpitations.
0:57:15 > 0:57:17All the way to this beach in Australia,
0:57:17 > 0:57:24having let a crocodile free in the ocean to do science for us.
0:57:24 > 0:57:29I'm strangely moved. I never thought I'd say that about a croc.
0:58:18 > 0:58:20Subtitles by Red Bee Media Ltd