0:00:09 > 0:00:15In the remote jungles of Papua New Guinea, an international team of scientists and filmmakers
0:00:15 > 0:00:18has been searching for rare and endangered creatures.
0:00:21 > 0:00:25We could find something really, really spectacular inside here.
0:00:25 > 0:00:27I guess that's the hope.
0:00:28 > 0:00:31Two weeks in and they've made an impressive start.
0:00:34 > 0:00:36What an extraordinary looking fish.
0:00:36 > 0:00:40- They've found the weird... - I have no idea what that will become.
0:00:40 > 0:00:45- The wonderful. - Now you can really see how tiny he is like compared to your thumb.
0:00:45 > 0:00:48And discovered animals unknown to science.
0:00:48 > 0:00:53I'll bet you any money that wasp right there that's walking along that leaf is a new species,
0:00:53 > 0:00:55I bet you any money.
0:00:55 > 0:00:58They've hunted high and low.
0:00:58 > 0:01:04Now, beneath the forest floor, Steve Backshall is pushing deep into a cave,
0:01:04 > 0:01:07one of the few places on Earth where no-one has been before.
0:01:10 > 0:01:13I've never seen anything like this before in my life.
0:01:13 > 0:01:15This is extraordinary!
0:01:41 > 0:01:45Just above Australia in the western Pacific
0:01:45 > 0:01:47lies Papua New Guinea.
0:01:47 > 0:01:52Cloaked in dense rainforest, these valleys are among the most isolated on the planet.
0:01:56 > 0:02:03The main base camp is on the slopes of an extinct volcano, Mount Bosavi.
0:02:03 > 0:02:07Further east, a smaller team is on the island of New Britain.
0:02:07 > 0:02:11They're exploring an underground river cave, mapping it as they go.
0:02:11 > 0:02:15This is one of the most remote, inaccessible places on the planet
0:02:15 > 0:02:20and there genuinely are dark corners of Papua New Guinea that no human being has ever been to before.
0:02:20 > 0:02:24This place is absolutely ripe for exploration.
0:02:24 > 0:02:26It's risky.
0:02:26 > 0:02:30Just to get in means abseiling 80 metres to the cave entrance.
0:02:34 > 0:02:38Oh, it's pretty nippy, isn't it?
0:02:38 > 0:02:43Steve Backshall is the expedition climber, caver and naturalist.
0:02:43 > 0:02:46Oh, this is unbelievable!
0:02:46 > 0:02:50- Look at that.- What an unbelievable amount of water.
0:02:50 > 0:02:52Welcome to Mageni river cave.
0:02:53 > 0:02:57He's joined the Anglo-French team who first discovered this cave.
0:02:57 > 0:02:59The locals call it Mageni.
0:03:01 > 0:03:06They're led by pioneering British caver Dave Nixon, known as Moose.
0:03:07 > 0:03:10I remember coming up here
0:03:10 > 0:03:14really, really excited, not knowing what was at the top.
0:03:14 > 0:03:18Well, it makes you feel so alive.
0:03:18 > 0:03:23Their aim is to press further into this uncharted cave
0:03:23 > 0:03:25and map passages never seen before by man.
0:03:27 > 0:03:29Plus 5.7.
0:03:29 > 0:03:36Lucy is bouncing a laser off the walls of the tunnel so we can figure out how big it all is.
0:03:36 > 0:03:41That's the whole purpose of surveying, it's just to map out the size of the caverns.
0:03:41 > 0:03:46Jean-Paul, this joint is developed on
0:03:46 > 0:03:5050 degrees, 230. 50, 230.
0:03:54 > 0:04:01What fires them is the hope of finding a new, undiscovered route right through the mountain.
0:04:09 > 0:04:14700 miles west in the shadow of Mount Bosavi lies the base camp.
0:04:16 > 0:04:22A cluster of makeshift huts is home to the wildlife filmmakers, the expedition medic,
0:04:22 > 0:04:24expert trackers,
0:04:24 > 0:04:26cooks...
0:04:27 > 0:04:30and, at its heart, the scientists.
0:04:30 > 0:04:33Leading them is Dr George McGavin.
0:04:34 > 0:04:37I'm heading up a team of scientists, experts in their own field.
0:04:37 > 0:04:44Our aim is to document what animals live in and around this giant, extinct volcano,
0:04:44 > 0:04:48and also to search for any new species, and there must be hundreds.
0:04:49 > 0:04:52The cooks are preparing the dinner,
0:04:52 > 0:04:55when their fishing nets land something bigger
0:04:55 > 0:04:56than they'd bargained for.
0:04:58 > 0:05:01George is on hand to help.
0:05:03 > 0:05:04It's a crocodile, I think.
0:05:13 > 0:05:17Croc expert Paul O'Dowd has to work fast but carefully.
0:05:17 > 0:05:20It's really essential that we secure the front end,
0:05:20 > 0:05:22and the jaws have to be tied shut otherwise
0:05:22 > 0:05:24they could take somebody's hand off.
0:05:24 > 0:05:26But she's really growling,
0:05:26 > 0:05:28you can feel that "grrrr" in her throat.
0:05:28 > 0:05:31She's not a happy croc at all.
0:05:31 > 0:05:36Almost unnoticed in the net, there's a venomous catfish.
0:05:36 > 0:05:37There's a big fish here
0:05:37 > 0:05:41and the spine is loaded with very nasty toxins,
0:05:41 > 0:05:46and if that jabs into Paul's hand or my hand, not nice,
0:05:46 > 0:05:48you'd be a very sick person.
0:05:48 > 0:05:52Actually, George, maybe with your free hand
0:05:52 > 0:05:55could you just sort of make sure that this...?
0:05:55 > 0:05:59- That's the way.- It's not everyday that you have to restrain
0:05:59 > 0:06:01a large freshwater crocodile
0:06:01 > 0:06:06while holding a toxic spine of a catfish in your other hand.
0:06:06 > 0:06:10Out of the net, the crocodile is now free to go.
0:06:13 > 0:06:14Fantastic, happy ending.
0:06:14 > 0:06:17She's off, she's safe.
0:06:17 > 0:06:19Well done, mate.
0:06:24 > 0:06:27It's all in a day's work.
0:06:27 > 0:06:31But George's main job is running the jungle lab.
0:06:31 > 0:06:34This is an absolute monster.
0:06:36 > 0:06:40His team has already discovered 17 new species
0:06:40 > 0:06:43and catalogued hundreds of other animals.
0:06:48 > 0:06:53- What have you got there, Jack?- The latest creature has just been found
0:06:53 > 0:06:54on a tree right next to the lab.
0:06:54 > 0:06:57It's quite clearly a group of three caterpillars
0:06:57 > 0:06:58on that vine of some sort.
0:06:58 > 0:07:00I have no idea what that will become.
0:07:00 > 0:07:04It looks almost as if it's a snake.
0:07:04 > 0:07:07You know, it's quite disturbing if you're a bird I suppose.
0:07:07 > 0:07:12As an extra defence, two of them will thrash around like that.
0:07:12 > 0:07:16Well, what I think we should do is we should put them in a cage
0:07:16 > 0:07:21and just observe them, but it could be weeks until they actually pupate,
0:07:21 > 0:07:25which is the only way of finding out what they'll become.
0:07:28 > 0:07:31Some animals are showy,
0:07:31 > 0:07:35others hide away hoping they won't be seen.
0:07:39 > 0:07:44This one's cover has just been blown by wildlife cameraman Gordon Buchanan.
0:07:48 > 0:07:50Oh, do you know what that is?
0:07:50 > 0:07:52It's a beautiful fruit dove.
0:07:54 > 0:07:57That's what it's called, that's not my name for it.
0:07:57 > 0:07:59I love all the names of...
0:07:59 > 0:08:01especially birds in Papua New Guinea.
0:08:01 > 0:08:04You've got all these magnificent bird of paradise,
0:08:04 > 0:08:07magnificent rifle bird, the superb fruit dove,
0:08:07 > 0:08:10the beautiful fruit dove, they're all very descriptive.
0:08:10 > 0:08:15Unbelievably camouflaged sitting there. Such a good find.
0:08:18 > 0:08:21It's one of the jungle's more unassuming characters,
0:08:21 > 0:08:25but Gordon has his sights set on a far more flamboyant bird.
0:08:26 > 0:08:30Personally, I want to find Birds of Paradise.
0:08:30 > 0:08:33They are the most iconic bird family on the planet.
0:08:33 > 0:08:36They have fascinated every ornithologist, every naturalist
0:08:36 > 0:08:40since they were first discovered 400 years ago. I'm no different.
0:08:40 > 0:08:42Gordon's mission is to record
0:08:42 > 0:08:46one of the most extraordinary rituals in nature,
0:08:46 > 0:08:50the mating display of the Bird of Paradise.
0:08:55 > 0:08:57Underground, Steve and the caving team
0:08:57 > 0:09:00are battling against the white water river.
0:09:12 > 0:09:14Steve is the team's naturalist.
0:09:14 > 0:09:18Even in a cave, some creatures still survive.
0:09:21 > 0:09:23These cave crickets are real specialists
0:09:23 > 0:09:25at this kind of environment.
0:09:25 > 0:09:30They have tiny little eyes but really almost all of their senses
0:09:30 > 0:09:32are in these gigantic antenna.
0:09:32 > 0:09:36Look at that, I mean that is probably six times the length of the body.
0:09:36 > 0:09:39They're tactile. They tap around a bit in front of the cave
0:09:39 > 0:09:42just feeling its way, and also pick up chemical signals.
0:09:42 > 0:09:45So it works like a nose, like eyes
0:09:45 > 0:09:49and also a bit like a blind man's white stick as well.
0:09:49 > 0:09:51I think this one here is a female.
0:09:51 > 0:09:56Possibly the least pretty-looking girl in the world.
0:09:56 > 0:09:58In total darkness, looks are irrelevant.
0:09:58 > 0:10:02Above ground, appearances can be everything.
0:10:02 > 0:10:06Bird expert Jack Dumbacher's found a King Bird of Paradise.
0:10:06 > 0:10:08I would like to take a blood sample.
0:10:08 > 0:10:11So there's a small vein that runs right under the arm here,
0:10:11 > 0:10:13we can get the DNA from the blood.
0:10:13 > 0:10:15We can use that for genetic studies,
0:10:15 > 0:10:19and we can also use it to test whether or not the birds
0:10:19 > 0:10:22are carrying malaria or other blood diseases.
0:10:22 > 0:10:28Keeping a record of all the animals is expedition photographer Ulla Lohmann.
0:10:28 > 0:10:31I've never seen colours like that.
0:10:31 > 0:10:33I mean me being a photographer
0:10:33 > 0:10:36I love colours and especially when the light is just breaking
0:10:36 > 0:10:38into it's feathers, it's just magnificent.
0:10:38 > 0:10:42All these colours are to impress the female and their mating display.
0:10:42 > 0:10:45They flash all these colours, they have a special dance that they do
0:10:45 > 0:10:47and the female is very drab
0:10:47 > 0:10:50so she doesn't have any of these specialised colours,
0:10:50 > 0:10:51just the male has these.
0:10:53 > 0:10:57Completing the look are elaborate tail wires
0:10:57 > 0:10:59that play a big part in his courtship display.
0:10:59 > 0:11:03It's an important find, proof that Birds of Paradise
0:11:03 > 0:11:05live in this patch of forest.
0:11:05 > 0:11:11HIGH PITCHED SQUEAKING
0:11:11 > 0:11:14- What have you got, Jack? - Good to see you, Gordon.
0:11:16 > 0:11:18Caught up in that net.
0:11:18 > 0:11:21Let me just get my hand down in there so that he can't get away.
0:11:21 > 0:11:25Oh, a king! Oh, you beauty.
0:11:25 > 0:11:27Oh, my goodness me.
0:11:27 > 0:11:29They are quite incredible.
0:11:29 > 0:11:34All the Birds of Paradise are almost beyond belief.
0:11:34 > 0:11:37Jack releases it just where it was found.
0:11:39 > 0:11:43Well, it looks like he's happiest on a vertical perch.
0:11:44 > 0:11:47Birds of Paradise look stunning,
0:11:47 > 0:11:51but even more impressive is their courtship dance.
0:11:52 > 0:11:56Catching this on camera will draw Gordon deep into the jungle.
0:12:03 > 0:12:06These forests are now under threat.
0:12:06 > 0:12:09There's big money to be made from tropical timber.
0:12:11 > 0:12:16This forest giant has been growing here for between 100 and 150 years.
0:12:16 > 0:12:19The value of this tree when it's cut down to the landowner,
0:12:19 > 0:12:23the man who owns this tree, is only about £8.
0:12:23 > 0:12:27When it's prepared and shipped out as timber in the UK
0:12:27 > 0:12:29it will fetch £1,000 or more.
0:12:29 > 0:12:32Somebody is making a great deal of cash,
0:12:32 > 0:12:36and it's not the people who own this tree.
0:12:38 > 0:12:42Papua New Guinea's forests are peppered with hundreds of remote tribes.
0:12:44 > 0:12:47It's those tribes and not the government
0:12:47 > 0:12:49who own the land and the trees.
0:12:49 > 0:12:53Tribal elders have a difficult decision to make...
0:12:53 > 0:12:56Keep their forests,
0:12:56 > 0:12:58or sell the trees to the loggers.
0:13:01 > 0:13:03If we keep forests like this intact,
0:13:03 > 0:13:05we will reduce our chances
0:13:05 > 0:13:07of suffering the worst effects
0:13:08 > 0:13:12of global climate change and we'll save between 60 and 80%
0:13:12 > 0:13:14of all the world's species.
0:13:14 > 0:13:15For me, it's a no-brainer.
0:13:24 > 0:13:28In the cave, progress is slow and exhausting.
0:13:28 > 0:13:30They need to stop and refuel.
0:13:30 > 0:13:33The French have brought cheese,
0:13:33 > 0:13:35and the Brits,
0:13:35 > 0:13:37baked beans.
0:13:37 > 0:13:40Oh, please tell me you're not eating cold baked beans?
0:13:40 > 0:13:43- What's the matter with you, man? - Oh, you're all wrong!
0:13:44 > 0:13:45I'll have some of that, that's mine.
0:13:48 > 0:13:51No, the cheese, cheese is good.
0:13:51 > 0:13:55Oh, no, that absolutely turns my stomach.
0:13:55 > 0:14:01- Smell that. - This is actually pretty good for us.
0:14:01 > 0:14:05I mean we've really just been having a chocolate bar for lunch most days.
0:14:05 > 0:14:09To actually stop and have cheese and crackers, it's luxury!
0:14:09 > 0:14:12YORKSHIRE ACCENT: Eee, you don't know you're born, lad!
0:14:14 > 0:14:18From base camp, two boats head upstream.
0:14:18 > 0:14:21Gordon's first stop on his search for Birds of Paradise
0:14:21 > 0:14:24is a remote village where the feathers are used for costumes.
0:14:24 > 0:14:29Also on their way are George and expedition medic Jane Stevenson.
0:14:35 > 0:14:39The boats' engines disturb a colony of bats roosting in the treetops.
0:14:45 > 0:14:47This is quite spectacular.
0:14:47 > 0:14:51These are flying foxes, they're the largest bats on the planet.
0:14:51 > 0:14:53They are just amazing, look at the size of them.
0:14:53 > 0:14:57They must have a wingspan of about that.
0:14:57 > 0:15:00They eat, I think it's exclusively fruit.
0:15:00 > 0:15:04When they eat the fruit they pass through the seeds,
0:15:04 > 0:15:06so they are pretty much the species
0:15:06 > 0:15:10that is responsible for keeping this forest living and growing.
0:15:12 > 0:15:14Oh, wow!
0:15:29 > 0:15:34Fogomaiyu village is dominated by the extinct volcano Mount Bosavi.
0:15:34 > 0:15:37Contact with outsiders is rare.
0:15:39 > 0:15:42Yeah, it's an unbelievable welcome,
0:15:42 > 0:15:46you're sort of quite overwhelmed about somewhere like this
0:15:46 > 0:15:48and so many people just turn out
0:15:48 > 0:15:51with just big smiles on their face.
0:15:51 > 0:15:52Is he a big man in the village?
0:15:52 > 0:15:55- This man?- He's the chief.- Oh, I see.
0:15:57 > 0:15:58His name is Chief Ayambo.
0:15:58 > 0:16:01These villagers know more than anyone
0:16:01 > 0:16:04about Birds of Paradise and where they display.
0:16:04 > 0:16:06Thank you, thank you.
0:16:08 > 0:16:11Hello. It's Gordon, pleased to meet you.
0:16:11 > 0:16:15These feathers are from Birds of Paradise?
0:16:15 > 0:16:17Cassowary, OK.
0:16:19 > 0:16:22It's a very poor village of just 500 people.
0:16:22 > 0:16:25Medicines are in short supply
0:16:25 > 0:16:27and there's been a severe outbreak of malaria.
0:16:27 > 0:16:32Here in this particular village one of the biggest problems is access.
0:16:32 > 0:16:34They can't get out to hospitals,
0:16:34 > 0:16:35they can't get out to clinics,
0:16:35 > 0:16:38they can't get medicines brought in,
0:16:38 > 0:16:41and everything is so expensive for them that health
0:16:41 > 0:16:45has actually had to take a back seat really, to just pure survival.
0:16:45 > 0:16:47While Jane sets up a makeshift clinic,
0:16:47 > 0:16:49George meets the village elders
0:16:49 > 0:16:53to find out what the future holds for them and their forest.
0:16:53 > 0:16:56First of all, I want to thank you very much
0:16:56 > 0:17:01for us being able to be here in this fantastic forest land of yours.
0:17:01 > 0:17:08It has been a great honour. You own a huge area of valuable land.
0:17:08 > 0:17:12You could sell your land, you could sell your trees.
0:17:12 > 0:17:15What do you want to happen, what's the way forward?
0:17:30 > 0:17:34Well, you know, you're sort of stuck because you want certain things,
0:17:34 > 0:17:38you want to pay for education and healthcare and soap and things,
0:17:38 > 0:17:41but you don't have the means of earning the cash.
0:17:53 > 0:17:56How many children die here?
0:18:02 > 0:18:08At Jane's clinic, a concerned mother has brought in her feverish child.
0:18:08 > 0:18:10We need to be sponging this baby down.
0:18:10 > 0:18:15I'm going to test the baby for malaria but it probably is malaria.
0:18:15 > 0:18:19It's one of the biggest killers in the tropics.
0:18:19 > 0:18:23Out here, mosquito nets are virtually non-existent.
0:18:25 > 0:18:27Can you see there's two lines there?
0:18:30 > 0:18:34Jane's test confirms her worst fears.
0:18:34 > 0:18:38He is particularly vulnerable now. He has a raging fever
0:18:38 > 0:18:42and he has the worst type of malaria strain.
0:18:44 > 0:18:46This is today's dose,
0:18:46 > 0:18:48as soon as possible.
0:18:48 > 0:18:51Although the baby is getting quite upset with this
0:18:51 > 0:18:52it is absolutely the best thing.
0:18:52 > 0:18:55This will potentially save his life
0:18:55 > 0:18:59and without this there is a very high chance that he will die.
0:19:18 > 0:19:23A mile into the mountain, rescue from outside is next to impossible.
0:19:23 > 0:19:26The water here is very fast-flowing and deep,
0:19:26 > 0:19:28that's why we're wearing lifejackets,
0:19:28 > 0:19:31because really if you're spending a lot of time in the water
0:19:31 > 0:19:35try not to get too cold, and really just battling against the flow.
0:19:35 > 0:19:40Moose has put in these lines so you could traverse across safely.
0:19:42 > 0:19:46Whoa, it's pretty faster here, Moose.
0:19:46 > 0:19:50- Don't want to get swept away there, do you?- Watch your feet.
0:19:55 > 0:19:58Oh, it's like the North Sea. Freezing.
0:20:08 > 0:20:13Forcing themselves against the flow, the team press on into the darkness.
0:20:21 > 0:20:23Here he is. This is a dwarf kingfisher.
0:20:23 > 0:20:27You can see just how small he is.
0:20:27 > 0:20:32George is back at work with the other scientists.
0:20:32 > 0:20:36Look at that. It's really fast.
0:20:36 > 0:20:40Their work is vital if they are to prove this jungle is worth saving.
0:20:43 > 0:20:44Alanna Maltby is the bat expert.
0:20:44 > 0:20:47She's made another important find.
0:20:49 > 0:20:53This is the second potential new species of bat.
0:20:53 > 0:20:55- Amazing.- Yeah, really is amazing.
0:20:55 > 0:20:59It's really unusual to find new mammals and new bats,
0:20:59 > 0:21:03and to have two potential new species in the course of a couple of weeks,
0:21:03 > 0:21:06that's just that's like nothing I've ever come across.
0:21:06 > 0:21:11The frog man has been kept busy too.
0:21:11 > 0:21:16You could spend the whole day trying to catch one of these things.
0:21:16 > 0:21:22But this is yet another frog which Alan Allison has never seen before.
0:21:22 > 0:21:24It's an interesting little guy
0:21:24 > 0:21:27because I'm almost certain that it's a new species.
0:21:27 > 0:21:29This is exactly why I'm here.
0:21:29 > 0:21:34We're seeing animals in a 100 years time might not even be here.
0:21:37 > 0:21:39The scientists will report their findings
0:21:39 > 0:21:41to the government of Papua New Guinea
0:21:41 > 0:21:45to lend support in protecting Mount Bosavi's weird and wonderful wildlife.
0:21:47 > 0:21:50This is amazing, this is a really strange world.
0:21:50 > 0:21:52Here is a beetle larva.
0:21:52 > 0:21:55Over there, we have a tiny bat.
0:21:55 > 0:22:00So here is an animal with a backbone that is a fraction the size of this.
0:22:00 > 0:22:04Alanna, can I just compare the size of that bat
0:22:04 > 0:22:07to the size of this insect?
0:22:07 > 0:22:10Which one do you think is more beautiful, George?
0:22:10 > 0:22:12I have to confess, Alanna,
0:22:12 > 0:22:16on this occasion the bat does win it hands down.
0:22:16 > 0:22:19Even I couldn't really love this thing.
0:22:27 > 0:22:32In Mageni, the only respite from the deafening river
0:22:32 > 0:22:35is to enter one of its many side caverns.
0:22:35 > 0:22:41Wow, this is nothing like any other cave we've seen so far at Mageni.
0:22:41 > 0:22:43It's quiet, relatively dry.
0:22:43 > 0:22:46We can talk to each other without shouting.
0:22:46 > 0:22:48Yeah, it's incredible, isn't it?
0:22:48 > 0:22:51Looks at these stals, they're fantastic.
0:22:51 > 0:22:53Check this out here, Steve.
0:22:53 > 0:22:56See this formation, you've got a column that's formed
0:22:56 > 0:22:58where a stalactite has met a stalagmite.
0:22:58 > 0:23:00This is deposited on a mud floor,
0:23:00 > 0:23:03but can you see how it's all fractured and broken there?
0:23:03 > 0:23:07That's almost certainly as a result of earth movement, earthquakes.
0:23:07 > 0:23:10What do you think it would be like down here if...
0:23:10 > 0:23:12It would be terrifying, really would be terrifying.
0:23:15 > 0:23:20It's been a long day of caving and, two miles into the mountain,
0:23:20 > 0:23:22they have to find somewhere to sleep.
0:23:31 > 0:23:33It's dusk in the village.
0:23:33 > 0:23:36Tomorrow, Gordon will set off in search of Birds of Paradise.
0:23:36 > 0:23:39But tonight, the village elders have allowed him
0:23:39 > 0:23:41to see their head dresses.
0:23:46 > 0:23:48So this is from the Ragi Bird of Paradise.
0:23:48 > 0:23:51You are correct, some... Raggianna.
0:23:51 > 0:23:54Yeah, see I know what
0:23:54 > 0:23:55I'm talking about!
0:23:59 > 0:24:03OK. It's like having a personal dresser.
0:24:03 > 0:24:08- So do they use these headdresses for ceremonies?- For ceremonies, yes.
0:24:10 > 0:24:13Um, this is quite unexpected.
0:24:13 > 0:24:16A lot of early collections of Birds of Paradise
0:24:16 > 0:24:19and other bird species that are found in Papua New Guinea
0:24:19 > 0:24:23came from headdresses which were sort of taken by explorers
0:24:23 > 0:24:25and brought back to the west,
0:24:25 > 0:24:29and in those early days when they saw feathers like those,
0:24:29 > 0:24:31ornithologists just thought it was fakery,
0:24:31 > 0:24:35that it couldn't be a bird that had such spectacular feathers.
0:24:54 > 0:24:57I've made myself a little pit here
0:24:57 > 0:24:59and my sleeping bag ready to go.
0:24:59 > 0:25:03Tackle bag and half a carry mat, what more could a man ask for?
0:25:03 > 0:25:07The cavers have found a place for the night, but they're not alone.
0:25:10 > 0:25:12That is really weird.
0:25:12 > 0:25:15This is a freshwater crab from the outside
0:25:15 > 0:25:18and I would guess that it's probably been swept in here
0:25:18 > 0:25:20right from where the water's gathered for this cave.
0:25:20 > 0:25:23What's incredible though, to me,
0:25:23 > 0:25:26is if you look at it close up,
0:25:26 > 0:25:29its' absolutely covered in parasites.
0:25:29 > 0:25:31Rather grotesque white blobs
0:25:31 > 0:25:36which are kind of moving all over it, I mean look at those.
0:25:36 > 0:25:39I've never seen anything like this before in my life.
0:25:39 > 0:25:41It really lends to the sense
0:25:41 > 0:25:46this place has of being just like an alien landscape.
0:25:53 > 0:26:00It's enticing to think from here quite how much is unexplored,
0:26:00 > 0:26:03that's like what we've seen so far in this area.
0:26:03 > 0:26:05It's probably riddled with caves like this
0:26:05 > 0:26:09and some of them will never see the light of day, and never be explored.
0:26:09 > 0:26:12The team desperately need their rest.
0:26:12 > 0:26:16But in a small damp cave under a million tonnes of rock,
0:26:16 > 0:26:18sleep may not come easily.
0:26:29 > 0:26:32In the village, a tribal dance begins.
0:26:32 > 0:26:34THEY CHANT
0:26:40 > 0:26:43You've got everything that represents light and life in the forests.
0:26:43 > 0:26:47These guys wearing spectacular headdresses, Birds of Paradise,
0:26:47 > 0:26:50cockatoos, hornbills, all this sort of lush vegetation
0:26:50 > 0:26:52they've adorned themselves with.
0:26:54 > 0:26:56Centre stage are the feathers
0:26:56 > 0:27:01from one of the largest birds of paradise, the Raggianna.
0:27:03 > 0:27:05These are from Raggianna.
0:27:05 > 0:27:09Raggianna Bird of Paradise. And if you just look at the...
0:27:09 > 0:27:14Better from this angle. They look as if they've been doctored.
0:27:14 > 0:27:17They're just very un-feather like but very exquisite
0:27:17 > 0:27:22and that's just a small proportion of the feathers that are on this bird.
0:27:23 > 0:27:26If you think these costumes are elaborate,
0:27:26 > 0:27:30they are nothing compared to the birds themselves.
0:27:30 > 0:27:34This is a sort of an imitation of their splendour.
0:27:53 > 0:27:56WHISPERS: I've just woken up in the middle of the night.
0:27:56 > 0:27:59Well, I think it's the middle of the night, could be any time really.
0:27:59 > 0:28:04Bit sort of tossing and turning with weird dreams
0:28:04 > 0:28:09about scuttling white cave crabs and things.
0:28:10 > 0:28:13I've suddenly picked up a fever,
0:28:13 > 0:28:16I've had the shakes, very high temperature,
0:28:16 > 0:28:22and a couple of sort of weak panic attacks with it as well.
0:28:22 > 0:28:24I feel absolutely awful.
0:28:27 > 0:28:31Just typical that it would happen tonight.
0:28:31 > 0:28:34Lie back down and try and get a bit more sleep
0:28:34 > 0:28:38but just can't wait for the morning and get out, really.
0:28:48 > 0:28:52At daybreak, Gordon sets off with trackers from the village
0:28:52 > 0:28:55looking for birds of paradise that are displaying.
0:29:00 > 0:29:03The one saving grace we have is that Birds of Paradise are very vocal.
0:29:03 > 0:29:05We want to see them displaying
0:29:05 > 0:29:07which will give us an indication
0:29:07 > 0:29:10that they are in this area and they are breeding.
0:29:10 > 0:29:13I'm hoping that we can hear those sounds
0:29:13 > 0:29:17and zone in on them and find the birds based on their calls.
0:29:25 > 0:29:27It's definitely getting rougher.
0:29:31 > 0:29:33Pouring down from Mount Bosavi
0:29:33 > 0:29:37is a network of rivers that they must cross.
0:29:44 > 0:29:47So, how are we going to get across this?
0:29:47 > 0:29:49We will use a log to make a bridge.
0:29:49 > 0:29:52Put a log across, there's no way to walk round, no?
0:29:53 > 0:29:58They swim when they can, but the camera gear must be kept dry.
0:30:01 > 0:30:04They've managed to get that over but if you fell in there
0:30:04 > 0:30:06with a backpack on, you'd be a goner.
0:30:30 > 0:30:35Deep underground, Steve Backshall is going nowhere.
0:30:35 > 0:30:40I still have a really heavy fever and it was spiking in the night.
0:30:40 > 0:30:43I was actually hallucinating it was that bad.
0:30:43 > 0:30:47I just feel like I want everyone else to go out
0:30:47 > 0:30:49and just leave me here.
0:30:49 > 0:30:52That's not an option though, is it?
0:30:52 > 0:30:54Well, it's not really an option,
0:30:54 > 0:30:59no, but I feel absolutely desperate.
0:30:59 > 0:31:01Tim Fogg is in charge of safety.
0:31:01 > 0:31:06It's his job to get Steve out of the cave.
0:31:06 > 0:31:08This is a very, very remote place.
0:31:08 > 0:31:10We're a long way from home.
0:31:10 > 0:31:14We're going to have to help them as much as we can,
0:31:14 > 0:31:19but basically he's going to need to get out under his own steam.
0:31:21 > 0:31:24Even though the water's warm,
0:31:24 > 0:31:27it still gets to you a bit after a while.
0:31:27 > 0:31:30Steve is weak and running a high temperature.
0:31:30 > 0:31:34Lets go, Steve. Let's go, mate, straight through here.
0:31:34 > 0:31:36You all right?
0:31:36 > 0:31:38Come on, mate, you're doing great.
0:31:49 > 0:31:55Calling from the canopy is a King Bird of Paradise.
0:31:55 > 0:31:57Gordon's found a display site.
0:32:09 > 0:32:11It's right here, come over.
0:32:13 > 0:32:18Fortunately, the King does his courting close to the ground.
0:32:18 > 0:32:21Oh, yeah, there he is.
0:32:21 > 0:32:24I'm hoping that this is him getting ready for his big display,
0:32:24 > 0:32:27just making sure that all his feathers are in order.
0:32:27 > 0:32:31Great, now that's just the start of the display
0:32:31 > 0:32:34as he jumps from either side of the branch.
0:32:34 > 0:32:37These tail wires whack back and forward
0:32:37 > 0:32:39and that's attracting the female even more.
0:32:39 > 0:32:44Oh... duck down again. Oh, there he is right out in the open.
0:32:44 > 0:32:47OK, he's started displaying.
0:32:47 > 0:32:49He's brought the little tail
0:32:49 > 0:32:52that he does have right up to flat with his back,
0:32:52 > 0:32:55and tail wires are kind of dangling about over his head,
0:32:55 > 0:32:58and he's sort of jiggling back and forwards.
0:32:58 > 0:33:01There must be a female up there.
0:33:01 > 0:33:05On, yeah, there we go, there's a female.
0:33:05 > 0:33:09Gosh, you wouldn't even think that that was the same species.
0:33:18 > 0:33:23It's very easy to relate to this Bird of Paradise behaviour
0:33:23 > 0:33:27because it pretty much mimics what a lot of men do
0:33:27 > 0:33:29is to show off to attract women.
0:33:29 > 0:33:33It's the kind of disco scenario, the best dancer,
0:33:33 > 0:33:40the best dressed man sort of gets the best choice of the women, he gets the best women.
0:33:40 > 0:33:42Very easy to understand.
0:33:46 > 0:33:48Amazing.
0:33:50 > 0:33:52Practically every life form
0:33:52 > 0:33:56that lives in this rainforest depends on the forest.
0:33:56 > 0:34:00You lose the forest, you lose the animals just like that,
0:34:00 > 0:34:02it's a very, very simple equation.
0:34:02 > 0:34:04You can't have one without the other.
0:34:04 > 0:34:08And that's the terrible thing about deforestation.
0:34:08 > 0:34:11You're not just losing the trees you're losing this habitat
0:34:11 > 0:34:13and everything that depends on it.
0:34:21 > 0:34:24In the lab, the scientists are finding yet more evidence
0:34:24 > 0:34:26of the richness of this forest.
0:34:28 > 0:34:32Satellite images reveal just how rapidly jungle is disappearing.
0:34:34 > 0:34:40This is the scariest series of images that I think I've ever seen.
0:34:40 > 0:34:42This is pristine rainforest
0:34:42 > 0:34:45that has existed in this area for 10,000 years.
0:34:45 > 0:34:4916 years ago it looked like that,
0:34:49 > 0:34:52virtually untouched.
0:34:52 > 0:34:56And the most up-to-date image shows the road for forestry vehicles
0:34:56 > 0:34:59which are coming in to extract the wood,
0:34:59 > 0:35:03now spreading like veins all over the forest,
0:35:03 > 0:35:07and this is only 20 miles from here.
0:35:09 > 0:35:13This makes the mission to explore Bosavi's forests
0:35:13 > 0:35:15all the more urgent.
0:35:15 > 0:35:18I think the thing that's really striking about this
0:35:18 > 0:35:19is the incredible diversity,
0:35:19 > 0:35:22so every time you turn a corner you see a new insect,
0:35:22 > 0:35:23you see a new frog,
0:35:23 > 0:35:25you see a new beetle and that's the fun of it.
0:35:27 > 0:35:31George has been mesmerized by his mysterious caterpillars.
0:35:32 > 0:35:37At last, they're starting to pupate.
0:35:37 > 0:35:40There is one of the little caterpillars.
0:35:40 > 0:35:43It's hidden away on this folded leaf
0:35:43 > 0:35:47and it's also taken a bit of this dry leaf,
0:35:47 > 0:35:51and it's used a bit of silk, and it's now just hiding.
0:35:51 > 0:35:56Now I'm assuming what it'll do now is to pupate.
0:35:56 > 0:35:59But wouldn't it be great to be here when those hatched out
0:35:59 > 0:36:05and then we'd at last know what this amazing animal becomes as an adult.
0:36:14 > 0:36:17At Mageni, the cavers have reached the surface camp
0:36:17 > 0:36:19and Steve's fever is subsiding.
0:36:22 > 0:36:28The rest of the team also need time to recover.
0:36:33 > 0:36:39I have a kind of a rash on my body, just like burning my whole body.
0:36:39 > 0:36:42It's not very nice.
0:36:44 > 0:36:48Steve's gaining strength and keen to get back to the job.
0:36:48 > 0:36:50Before they go into the cave,
0:36:50 > 0:36:53they're adding their new data to the computer.
0:36:53 > 0:36:54In the 21st century,
0:36:54 > 0:36:58it's rare to be able to explore and chart a whole new river system.
0:36:58 > 0:37:02Well, this crunches all the numbers that we get when we go surveying,
0:37:02 > 0:37:06and very cleverly creates a 3D model of the cave.
0:37:06 > 0:37:09And it's by no means fully explored
0:37:09 > 0:37:11and there's various leads on here,
0:37:11 > 0:37:13these little dead ends or look like dead ends,
0:37:13 > 0:37:16these are passages that we didn't explore fully
0:37:16 > 0:37:18and are waiting to be surveyed.
0:37:18 > 0:37:22And it's just a matter of getting there and doing it and that's what burns a hole in my head.
0:37:24 > 0:37:26The lure of the cave is strong.
0:37:26 > 0:37:32Fired up again, the team drop back down the cliff side.
0:37:43 > 0:37:45Truly, this is the land of the unexpected.
0:37:50 > 0:37:53On the eastern slopes of Mount Bosavi,
0:37:53 > 0:37:55Gordon is still tracking birds
0:37:55 > 0:37:59when he discovers a river erupting from deep underground.
0:38:02 > 0:38:06This is a place with lots of strange things
0:38:06 > 0:38:09and this is another one of them.
0:38:09 > 0:38:12This is the start of a river, a river that...
0:38:12 > 0:38:17well, actually, no, it's not the start because this river is flowing underground.
0:38:17 > 0:38:20It is just very peculiar.
0:38:20 > 0:38:22All of this water getting pushed,
0:38:22 > 0:38:28a huge quantity of water that's flowing down from Bosavi underground
0:38:28 > 0:38:31into a big channel that wells up here.
0:38:31 > 0:38:37And I would say that this is the best example of the power of water
0:38:37 > 0:38:41and unseen goings on, things that are going on way beneath our feet.
0:38:50 > 0:38:54And then, at last, high in the trees above Gordon,
0:38:54 > 0:38:57the sound he's been hoping for.
0:38:59 > 0:39:02It is a Raggianna Bird Of Paradise calling.
0:39:02 > 0:39:06This time of day it will still be displaying.
0:39:06 > 0:39:08It's great to know that they're in here,
0:39:08 > 0:39:11and it's definitely one I want to try and film
0:39:11 > 0:39:13cos they are gobsmackingly beautiful.
0:39:16 > 0:39:20The Raggianna displays only in the treetops.
0:39:20 > 0:39:24Gordon shoots a line 20 metres up a nearby tree.
0:39:24 > 0:39:28He'll have to haul himself and all his kit up into the canopy.
0:39:30 > 0:39:36Few people have ever seen a Bird Of Paradise, let alone, you know,
0:39:36 > 0:39:41sat up in a treetop with them so there is a real sense of privilege.
0:39:48 > 0:39:52Gordon must move quietly, so he doesn't drive the birds away.
0:40:01 > 0:40:03Oh, bats!
0:40:03 > 0:40:05Lots of them.
0:40:05 > 0:40:08Steve and the cavers are back in Mageni,
0:40:08 > 0:40:12retracing their steps to where their exploration left off.
0:40:18 > 0:40:20Oh, yeah!
0:40:20 > 0:40:25And it's not long before their effort pay off.
0:40:25 > 0:40:31- Just found a lead.- What, a new passage? Fantastic!- I know, I know.
0:40:31 > 0:40:33If you look down there you can see the river.
0:40:33 > 0:40:36Oh, my god, it's a proper river.
0:40:36 > 0:40:39Yeah, no-one's been down there ever.
0:40:39 > 0:40:41We're the first people here.
0:40:41 > 0:40:43There's a waterfall down there.
0:40:43 > 0:40:46Come on, without further ado.
0:40:49 > 0:40:54This new passage is drawing them down a side channel of the main river.
0:40:56 > 0:41:00Oh, I'm soaking!
0:41:00 > 0:41:03It's steep and it's getting narrower
0:41:03 > 0:41:07but it could be a new way out of the mountain.
0:41:07 > 0:41:09I don't know if you can make this out,
0:41:09 > 0:41:11we haven't really got enough light to show,
0:41:11 > 0:41:14but we're sitting at the top of a white water cataract
0:41:14 > 0:41:17which is raging off down into the mountain.
0:41:17 > 0:41:20And we're going to tread really carefully but I think,
0:41:20 > 0:41:23do you think, Moose, we should try and push on a little bit?
0:41:23 > 0:41:26- Stick to the right-hand side and then we'll cross over.- OK.
0:41:31 > 0:41:33In his treetop, Gordon is in position
0:41:33 > 0:41:35but everything is against him.
0:41:35 > 0:41:38BUZZING
0:41:38 > 0:41:41Bloody bees!
0:41:46 > 0:41:47Get off.
0:41:47 > 0:41:50He's level with the Raggianna display site
0:41:50 > 0:41:52but the heavens have opened.
0:41:54 > 0:41:58Little chance of these birds showing up.
0:41:59 > 0:42:02It's pouring down and apparently
0:42:02 > 0:42:05Birds of Paradise don't like to display in the rain.
0:42:05 > 0:42:11- I can hear them off... There you go, there's one. - BIRD CHIRPS
0:42:11 > 0:42:16But the chances of them coming in and doing their stuff, I would say, would be very slim.
0:42:16 > 0:42:19Come on, you monkey.
0:42:22 > 0:42:25Oh. Jeez, there's one there. There's one there.
0:42:25 > 0:42:29Oh, you little darling.
0:42:30 > 0:42:36Oh, jeez, there's two of them, there's' two of them!
0:42:36 > 0:42:38Wow! Look at that.
0:42:40 > 0:42:43Despite the rain, there are two males trying to outshine each other.
0:42:43 > 0:42:48That is the most weird and fantastic bird I've ever seen.
0:42:48 > 0:42:52What's going on, what's going on?
0:42:52 > 0:42:55They're trying to show who's the fittest
0:42:55 > 0:42:57with a complicated dance routine.
0:43:00 > 0:43:02Wow!
0:43:02 > 0:43:07It almost looks as if the males are showing off to each other.
0:43:07 > 0:43:10OK, there must be a female around.
0:43:10 > 0:43:15Until a female turns up, these males can't afford to stop their display
0:43:15 > 0:43:20and Gordon can't afford to take his eyes off them.
0:43:20 > 0:43:24There's a huge volume of water pushing through here.
0:43:24 > 0:43:27It's a good job the ground's grippy.
0:43:27 > 0:43:31In the cave, the route they found is getting treacherous.
0:43:31 > 0:43:35You're best standing on the ridge, that's it.
0:43:35 > 0:43:37This is no place to lose your grip.
0:43:37 > 0:43:41- Oh, look at that. - We're going to cross here.
0:43:45 > 0:43:51This is extraordinary. It's a real raging, raging river.
0:43:51 > 0:43:55There's an incredible amount of water passing through here.
0:43:55 > 0:43:58If you actually lost your footing and got swept away down there,
0:43:58 > 0:44:01you could get sucked into a place where the water just goes underground
0:44:01 > 0:44:05with no air or you could just get swept over the top of a waterfall.
0:44:05 > 0:44:08Same time, though, this has got to be one of the most exciting things I've ever done.
0:44:08 > 0:44:15Every single step we take is new, no-one's ever seen any of this.
0:44:21 > 0:44:25Finding and exploring a brand new underground route
0:44:25 > 0:44:28is the ultimate thrill for any caver.
0:44:28 > 0:44:31It's a waterfall.
0:44:31 > 0:44:33We're in the top of a waterfall.
0:44:33 > 0:44:36You can hear the noise of it. It's like a 747 taking off.
0:44:38 > 0:44:41The passage goes off in that direction
0:44:41 > 0:44:43so we've got some more exploring to do.
0:44:43 > 0:44:46That's fantastic!
0:44:46 > 0:44:50To descend any further, they'll need climbing equipment.
0:44:50 > 0:44:53The guys have kindly said I could go first,
0:44:53 > 0:44:58so I'm going to head down, see what we can find down there.
0:44:58 > 0:45:01See you at the bottom, mate.
0:45:09 > 0:45:13This is an absolutely awesome place.
0:45:13 > 0:45:15It's just thunderous.
0:45:15 > 0:45:17Honestly, just the noise of it
0:45:17 > 0:45:20makes you feel like you're being battered the entire time.
0:45:20 > 0:45:24Heading down there now, into the unknown.
0:45:32 > 0:45:35Go, go, go, go!
0:45:35 > 0:45:40That is the biggest scorpion I have seen yet here.
0:45:40 > 0:45:43In the jungle, George is out collecting.
0:45:45 > 0:45:48Come on, we want something nice.
0:45:48 > 0:45:50The base camp phase of the expedition is nearing an end
0:45:50 > 0:45:54but the forest is still delivering surprises.
0:45:54 > 0:45:59There's a little tiny frog, a little tiny frog just sitting on that leaf.
0:45:59 > 0:46:02Think we should collect that for Alan, our frog expert.
0:46:05 > 0:46:07Alan, I bring you frog.
0:46:07 > 0:46:11Is it a tree frog, very sort of adhesive little feet?
0:46:13 > 0:46:16Indeed it is a tree frog. It's an interesting one, this is a great one.
0:46:16 > 0:46:20Wow, it's the first one we've found here, we have not found this yet.
0:46:20 > 0:46:24It could either be a new species or on it's way to being a new species.
0:46:24 > 0:46:26- Yes!- Thank you so much.
0:46:28 > 0:46:32Across the lab, photographer Ulla has set up a time-lapse studio.
0:46:34 > 0:46:38That's looking so close.
0:46:38 > 0:46:42One of George's mystery caterpillars is now a chrysalis
0:46:42 > 0:46:45and could hatch at any time.
0:46:45 > 0:46:50What I really want is to give it a little poke just to see if it's...
0:46:50 > 0:46:53I can't just give it a little poke, no?
0:46:53 > 0:46:58Well, no, it would really spoil the time lapse, so sorry.
0:47:02 > 0:47:05The cameras should capture the very moment it emerges.
0:47:06 > 0:47:08I know what's going to happen.
0:47:08 > 0:47:12It'll emerge and it'll be the most tedious, boring little moth.
0:47:32 > 0:47:35Oh, no, I don't like the look of this at all.
0:47:36 > 0:47:38This is the way on...
0:47:38 > 0:47:41Well, possibly.
0:47:41 > 0:47:44The water seems to have levelled out a little bit
0:47:44 > 0:47:46and it goes underneath a narrow ceiling here,
0:47:46 > 0:47:49and it looks like there might be more beyond it.
0:47:50 > 0:47:53What do you reckon, Moose?
0:47:53 > 0:47:57I reckon it's a duck of about four-five metres.
0:47:57 > 0:47:59You know this is about the worse thing you could do
0:47:59 > 0:48:02is to go into the unknown in fast-flowing water,
0:48:02 > 0:48:04cos you get whisked away, yeah?
0:48:13 > 0:48:16Only Steve and Moose will press on into the unknown.
0:48:16 > 0:48:18The rest of the team can only wait.
0:48:34 > 0:48:39In the tree top, Gordon's two male Raggiannas are upping their game.
0:48:42 > 0:48:45Their efforts have attracted a potential mate.
0:48:47 > 0:48:49Oh, there you go, female.
0:48:49 > 0:48:53She'll decide which is her favourite.
0:48:59 > 0:49:04Now this could get quite interesting.
0:49:04 > 0:49:05Despite the rain,
0:49:05 > 0:49:11they're both putting in this display because there's competition.
0:49:11 > 0:49:13And not only is there competition,
0:49:13 > 0:49:16there is a female around and that's what it's all about.
0:49:16 > 0:49:18Oh, man,
0:49:18 > 0:49:21doesn't get much better than this.
0:49:21 > 0:49:23Not when it comes to birds.
0:49:23 > 0:49:25Oh, two females! Jeez.
0:49:25 > 0:49:29A second female also shows an interest.
0:49:29 > 0:49:31Come on, I see what you can get.
0:49:31 > 0:49:36Oh, he's pecking her, oh easy on.
0:49:38 > 0:49:43This is quite incredible
0:49:43 > 0:49:48that these birds have evolved to look like this, to sound like this,
0:49:48 > 0:49:51to act like this just to win a mate.
0:49:52 > 0:49:56Well, it looks as if she's decided who she likes.
0:49:56 > 0:50:02Oh, yes, you will be mine.
0:50:08 > 0:50:13As one male makes the biggest impression, the second knows he's beaten.
0:50:14 > 0:50:17Oh, mating, he's mating, oh, lovely.
0:50:22 > 0:50:24Oh, I can't believe we've got that.
0:50:24 > 0:50:29Now I wonder if he'll actually mate with both of them in the one day.
0:50:29 > 0:50:34This male's done well, he's won over the second female.
0:50:34 > 0:50:36She is not boring at all.
0:50:36 > 0:50:38He looks really doing his stuff.
0:50:45 > 0:50:49That's what it's all about with Birds of Paradise,
0:50:49 > 0:50:53is if you look that great you're going to get more than one lady.
0:50:55 > 0:50:58And off she goes.
0:50:58 > 0:51:03You don't really get too many days like this.
0:51:03 > 0:51:06Off he goes, beautiful. Ta-da.
0:51:15 > 0:51:18Oh, lord. This goes on forever.
0:51:20 > 0:51:26Steve and Moose have been alone inside the flooded cave for 15 minutes.
0:51:28 > 0:51:31The river's deep and the ceiling is getting lower.
0:51:31 > 0:51:35It's not as hectic as it was the other side.
0:51:35 > 0:51:39But it's still running quite fast.
0:51:39 > 0:51:43Then the river disappears into an airless chamber.
0:51:43 > 0:51:47As far as exploration of this part of the cave is concerned,
0:51:47 > 0:51:49this is the end of the line.
0:51:49 > 0:51:52Don't want to get washed into a watery grave down there,
0:51:52 > 0:51:54so let's not go any further.
0:51:54 > 0:51:57There's no way the cavers can go on.
0:51:59 > 0:52:02There's nothing more here for us. Let's head out.
0:52:05 > 0:52:08You know, we've reached the end, that's what we came here to do.
0:52:08 > 0:52:11We've actually found the end of this piece of passage,
0:52:11 > 0:52:13and now I think it's time to head home.
0:52:13 > 0:52:16The caving has been a success.
0:52:16 > 0:52:21They've found and charted a section of cave never before seen.
0:52:21 > 0:52:25But for Steve, the expedition is far from over.
0:52:40 > 0:52:44While George is asleep in his hammock, something stirs in the lab.
0:52:45 > 0:52:51The time-lapse camera watches as a moth chooses its moment to emerge.
0:53:05 > 0:53:08George?
0:53:17 > 0:53:21Oh, that's beautiful, look at that!
0:53:21 > 0:53:23Absolutely...
0:53:23 > 0:53:24please don't fly off.
0:53:26 > 0:53:31I have never seen a moth like this before in my life.
0:53:31 > 0:53:34Don't fly off, please don't fly off.
0:53:34 > 0:53:38Just look at the pattern on the back of that wing.
0:53:38 > 0:53:40Wow, they are amazing.
0:53:40 > 0:53:42When you see something in the wild
0:53:42 > 0:53:46and you don't know if it'll be a moth or what sort of moth,
0:53:46 > 0:53:50and the only way of finding out what any immature stage will become
0:53:50 > 0:53:53is to rear them up, which is exactly what we did.
0:53:53 > 0:53:58My wife has her birthday today and I'm not there,
0:53:58 > 0:54:05and if these turn out to be new species, I will name them after her.
0:54:05 > 0:54:07I really hope they are new species.
0:54:13 > 0:54:19In base camp, Steve is preparing for the next challenge of the expedition.
0:54:23 > 0:54:27The team's new destination is the volcanic crater of Mount Bosavi.
0:54:30 > 0:54:34Its fortress walls have kept the hunters out and animals in.
0:54:36 > 0:54:40This isolated cauldron could conceal spectacular new species.
0:54:40 > 0:54:43Steve, look at that.
0:54:43 > 0:54:46There it is, Mount Bosavi. I've got to say it's so much like
0:54:46 > 0:54:49something you'd expect to see in a geography textbook.
0:54:49 > 0:54:53This whole volcano is a million years old.
0:54:53 > 0:54:57The last time it blew up was 200,000 years ago.
0:54:57 > 0:54:59Yeah, sounds about right, so potentially
0:54:59 > 0:55:02everything that's in there's been trapped in there for 200,000 years.
0:55:02 > 0:55:05So the great thing is, of course, is that also if there is any hunting
0:55:05 > 0:55:09it tends to be done on the low-lying part.
0:55:09 > 0:55:11Who is going to climb up into the crater to hunt stuff
0:55:11 > 0:55:16when you don't have to, so this whole area is going to be really...
0:55:16 > 0:55:18Very, very exciting.
0:55:18 > 0:55:24- You talk about lost worlds, well this is just, it doesn't get any better than this.- It is amazing.
0:55:31 > 0:55:33Steve is leading the advance party,
0:55:33 > 0:55:35paving the way for the rest of the team.
0:55:35 > 0:55:38Come on, guys, good luck.
0:55:43 > 0:55:47They're going to build a camp right in the heart of the crater.
0:55:58 > 0:56:02The survey of the animals around base camp is now complete,
0:56:02 > 0:56:04and its time to move on.
0:56:08 > 0:56:12In just four weeks, the scientists have found and catalogued hundreds of animals.
0:56:12 > 0:56:17A staggering 29 are believed to be completely new to science.
0:56:21 > 0:56:23Yeah, the trip's been really great.
0:56:23 > 0:56:27We were able to get a lot of birds in the nets, a lot of bats as well working with Alanna.
0:56:27 > 0:56:29We have well over 90 species between us
0:56:29 > 0:56:31and I haven't even made the final total,
0:56:31 > 0:56:33it will probably be even more than that.
0:56:34 > 0:56:37The next destination is beyond the clouds.
0:56:39 > 0:56:43The ancient crater inside Mount Bosavi itself.
0:56:43 > 0:56:49They'll be the first scientists ever to explore this lost world.
0:57:01 > 0:57:07This is the crater rim we're about to cross now. And that is the crater.
0:57:09 > 0:57:12I didn't prepare myself for the size of it.
0:57:28 > 0:57:30All the wildlife, all the plants
0:57:30 > 0:57:33that are here have been trapped inside by all of these walls.
0:57:33 > 0:57:37It's almost like the inside of the crater is kind of like an island.
0:57:37 > 0:57:42We could find something really, really spectacular inside here.
0:57:42 > 0:57:44I guess that's the hope.
0:57:47 > 0:57:53Next time, George witnesses the birth of a new mountain.
0:57:53 > 0:57:58To be absolutely honest with you I'm actually feeling quite apprehensive.
0:57:58 > 0:58:03You couldn't speed away from this in a hurry, you would be toast.
0:58:03 > 0:58:08In Bosavi's crater, the team find kangaroos that live in trees.
0:58:08 > 0:58:11The fact that this animal just wandered straight past us
0:58:11 > 0:58:14means the wildlife here has never been hunted before,
0:58:14 > 0:58:15it hasn't seen people before.
0:58:15 > 0:58:19And the most significant discovery of all, a new species
0:58:19 > 0:58:24of mammal, the largest of its kind anywhere in the world.
0:58:24 > 0:58:26Oh, my word, have a look at this.
0:58:26 > 0:58:29Oh, gosh!
0:58:37 > 0:58:40Subtitles by Red Bee Media Ltd
0:58:40 > 0:58:43E-mail subtitling@bbc.co.uk