Original subtitles

The South Pacific islands are the most isolated in the world.

Some are more than 4,000 miles from the nearest continent.

The odds against any life reaching these islands and flourishing were once minute.

But no matter how remote they may be, all have been colonised...

first by plants and animals...

and then by humans.

So who were those castaways?

And how did they ever reach these far-flung islands?

More than twice the width of the Atlantic Ocean,

the South Pacific is 10,000 miles wide.

Many of the pioneers who made it to the most easterly islands

set off from its far western corner.

And for most, New Guinea was the launch pad.

Three times the size of Britain,

this is the largest tropical island in the world.

And the island richest in animal life...

with some truly eye-catching residents.

Like this Goldie's bird of paradise.

Never filmed before,

Goldie's are just one of New Guinea's 38 species of bird of paradise,

all famed for their spectacular plumage.

Keen to show his impressive feathers to an attentive female,

the male clears the stage.

Now he's ready for a spot of serenading.

Females may be dull-looking, but they ARE very picky.

His solo fails to impress.

A second male arrives and takes centre stage.

But rather than fight, they strike up a duet!

This show of strength finally gets her attention.

The best-dressed Goldie gets the girl.

But while his feathers may have secured him a mate,

they're not strong enough to carry him off the island

and further east across the South Pacific.

Birds of paradise have sacrificed flight efficiency for flights of fancy.

So who did manage to colonise the South Pacific?

New Guinea's enormous landscape is carved up into thousands of isolated valleys.

Each shelters huge numbers of potential colonisers.

Amazingly, one in twenty of the world's insect species may live here...

as well as almost 300 species of mammal,

like the bizarre, egg-laying long-nosed echidna.

There are even kangaroos that have taken to the trees...

although somewhat precariously.

Did any of these animals ever travel east to other islands?

Around 300 species of reptiles thrive within this hothouse...

including the ubiquitous mourning gecko.

It is a highly adaptable creature,

but did it have the tools, stamina and luck to survive being a castaway?

One animal certainly did.

Humans.

Despite only arriving in New Guinea 40,000 years ago,

humans were soon established throughout the island's maze of hidden valleys.

Today, these people are known as Papuans,

and together, speak over 700 different languages -

more than any other island on Earth.

Yet despite their mastery of the island,

there was one creature they lived in awe of.

The giant, man-eating crocodile.

Even today, young men must endure a brutal initiation ceremony

in the belief that they will acquire

the strength and guile of these giant reptiles.

The chief shaman calls out to the crocodile gods,

asking for their blessing and protection.

The tribesmen form the sinuous shape of a moving crocodile.

At the rear, the crocodile's tail, a court jester lightens the mood...

momentarily.

For what follows is a gruelling and potentially lethal rite of passage.

These young men will be mutilated to resemble crocodiles.

The boys are led into the spirit house,

running the gauntlet of blows from their elders.

Inside, they find sharpened lengths of bamboo.

The sacred act of scarring is about to begin.

The ritual is a closely guarded secret.

Their cuts are thoroughly cleaned.

Killer infections are a real danger.

They go in as boys, but they come out as men -

crocodile men,

with the power to summon the great reptiles.

The scars on their back represent the animal's scales...

while their chests have become the crocodile's eyes.

If the animal you most fear might be watching your every move,

any act of appeasement is worth trying.

And New Guinea wasn't the last stop for saltwater crocodiles in the South Pacific.

Millions of years ago, these powerful reptiles

had already begun their push eastwards.

For any animal castaway,

the first hurdle would have been the 60-mile stretch of water

that separates New Guinea from the next group of islands - the Solomons.

Instead of one dominating island, like New Guinea,

the Solomons are made up of almost a thousand smaller jewels

scattered along a 900-mile chain.

All these islands erupted out of the sea and were ripe for colonisation.

The ancestors of these Solomon Islanders

made that initial 60-mile crossing some 30,000 years ago.

Whether their ancestors paddled across in hollowed-out tree trunks like these

or floated on giant bamboo rafts, no-one knows.

And with land occasionally in sight,

they would have surely been tempted to investigate.

By the time people arrived, the Solomons were packed

with almost a quarter of the plants and animals found in New Guinea...

including their old adversary, the saltwater crocodile.

A 60-mile swim would be an unimaginable feat for most animals,

but salties are not most animals.

One of the few crocodiles to tolerate saltwater,

they are also the largest and strongest swimmers.

Guided by an internal compass,

they made landfall throughout the Solomons

and became the most easterly population of crocodiles in the Pacific.

Once arrived, they'd have had plenty to feast on.

The waters surrounding New Guinea and the Solomons

are the richest and most diverse in the world.

Indeed, there are more species of fish on one of these reefs

than in the whole of the Caribbean.

But how did all this life reach the Solomons from New Guinea?

You might think it would be easy

for a fish to swim between these small islands.

But not so.

You wouldn't find these little fish in deep water.

The open ocean beyond their shallow reef is, in fact, a huge barrier.

So how did all these fish come to be here?

Colonising new reefs is a challenge faced by fish across the South Pacific,

but they have a simple solution.

Once a year, thousands of groupers gather on the reefs.

With the coming of the full moon, an extraordinary event unfolds.

They spawn.

A female darts up and releases millions of eggs, quickly followed by the males,

who jostle to fertilise them.

But starting new life can end in death.

Grey reef sharks.

Groupers are normally too quick for sharks...

but a distracted grouper is shark bait.

The sharks may snatch a few adults,

but millions upon millions of fertilised grouper eggs are picked up by the current.

Out in the open ocean, they hatch into larvae

and become part of the vast plankton soup.

And it's not just fish that depend on the whim of the open ocean

to disperse their larvae.

Land crabs and other crustaceans do, too.

But there's a deadline.

They each have a set number of days to reach new islands.

Astonishingly, these larvae are able to home in

on the smells and sounds of distant reefs.

Out of the millions of larvae that set off,

only a small fraction will succeed in colonising new islands.

Curiously, some freshwater fish also spawn at sea

and use the sea to help their larvae colonise rivers.

These freshwater eels in the Solomons began their lives hundreds of miles away,

possibly in a deep sea trench off New Guinea.

Yet as larvae and then elvers,

they made their way into these freshwater pools,

and over 40 years, grew into two-metre giants.

The eels are highly prized by the locals.

These Solomon Islanders handfeed them, not to fatten them up for dinner

but to encourage them to stick around.

By scavenging on whatever's decaying here,

the eels clean the islanders' precious pools of drinking water...

and over time, the honorary guests have become tame.

One day, these adult freshwater eels will return to the sea to spawn...

after which, they'll die.

For now, they are as good as pets.

Away from the coast, animals are thin on the ground.

The Solomons have only a quarter of the reptiles and birds that New Guinea has.

For mammals like echidnas and kangaroos, the water proved too great a hurdle.

But some mammals did make it here.

When it comes to reaching new islands,

flying must surely have been the easiest way to get there.

But the 60 miles between New Guinea and the Solomons

still proved a formidable challenge for many winged creatures.

With their four-foot wingspans,

giant fruit bats succeeded where other fliers failed.

Carrying undigested fruit seeds from New Guinea in their stomachs,

they inadvertently helped sow the Solomons' rainforests.

By day, these nocturnal fruit bats roost communally

in the safety of the tallest trees.

From the few bats that made it here, there are now 18 different species.

They have become the most widespread native mammal in the South Pacific.

East of the Solomons, the distance between islands increases dramatically.

It's now 1,000 miles of open ocean before the next island groups -

Fiji, Samoa and Tonga.

Of all these island clusters, Fiji is the largest...

made up of over 300 volcanic islands, formed some 40 million years ago.

Fiji is around two-thirds the size of the Solomons,

so remained a reasonable target for would-be colonisers.

Despite its isolation, it is still home

to nearly half the number of plant species found in the Solomons.

But animal colonisers were not so successful.

At night, the forests are eerily quiet.

Only a handful of bats made it here,

the only mammals to do so, and there are far fewer birds.

In the absence of ground predators,

invertebrates evolved into monsters.

This millipede is one of the biggest of its kind,

running almost a foot long.

Its diet of rotten vegetation may have sustained its ancestors

on their long journeys to these distant shores.

But how did they get here?

Perhaps more surprising, two species of frog also made it to Fiji.

Surprising because adult frogs quickly die in saltwater.

But the ancestor of this frog may have arrived here as a tadpole.

Tadpoles normally need pools of freshwater to develop in,

but these actually mature inside the egg.

So, on long journeys,

these eggs would have been like little survival capsules.

But the question remains - how did they ever reach these islands?

Maybe the same way as Fiji's most intriguing castaway of all.

Discovered only 30 years ago,

Fiji's largest surviving reptile was marooned

on a handful of its outer islands.

Crested iguanas.

They're one of the toughest and most saltwater-tolerant lizards around.

In the breeding season, males, nearly a metre long,

battle it out for a mate.

They begin with a gentle bout of competitive head-bobbing.

If no-one backs down, things become more animated.

The loser scrambles for cover.

So where did these large lizards come from?

Some speculate Asia, 4,000 miles to the west...

others, the Americas, 5,000 miles to the east.

But how did they end up here in Fiji?

One answer is that the iguanas, the frogs and the millipedes

were all carried here by powerful oceanic forces.

Every day, large waves beat down on tiny islands across the Pacific.

Imposing as they may be, these have little impact on island life.

But every year, much larger waves rise out of the ocean.

They're generated by underwater landslides and earthquakes.

Known as tsunamis, they can flatten coastlines.

Yet these destructive forces may have also brought life to some islands.

As tsunamis strike the coast, rafts of vegetation can be cast adrift.

Perhaps animals were caught up in those rafts, too.

Could this have been the answer to how these animals made it to Fiji?

After all, they are the hardiest of their kind

and could have survived long sea journeys.

Fiji's first animals washed up tens of millions of years ago.

But humans were slow off the block.

They only arrived here 3,500 years ago.

Their history remains thin on the ground.

The ruins of Nan Madol are one of only two ancient cities ever found in the Pacific.

With archaeological evidence so scarce,

the origins of the first people in the central Pacific were hotly debated.

Were they Papuans from New Guinea,

native Indians from the Americas, or another race of people from Asia?

Only very recently has their language been traced back to Taiwan...

and their pottery to the Philippines.

Combined with DNA analysis, evidence now points to the Lapita,

a seafaring people from Southeast Asia.

Back in the Solomons, on the tiny island of Taumako,

descendants of the Lapita still build and sail traditional voyaging canoes.

These canoes may look basic,

but their relative sophistication enabled the Lapita

to travel further into the Pacific than anyone had ever dared before.

They were no longer reliant on paddles alone - they had wind power.

Sails, perhaps similar to this crab-claw design,

enabled the Lapita to cover huge distances.

But with heavy sails, the canoes needed extra stability.

The Lapita added a second hull

and the long-distance outrigger canoe was finally born.

The Lapita's first voyages into the unknown must have appeared suicidal.

Although many were lost at sea, some Lapita DID reach new islands,

thanks to their extraordinary navigation skills.

This man can interpret the direction of land

by reading wave and swell patterns.

Like his ancestors, he carries in his head a complex wind map

detailing the various seasonal winds that serve as a compass.

And at night, he can navigate by the stars.

In craft like these, the Lapita reached the islands of Tonga,

2,000 miles east of New Guinea, in the heart of the South Pacific.

Further east, the odds of a castaway making land drop steeply

as the islands become fewer and even more isolated.

Almost all animal castaways would have died of exposure, hunger or thirst

long before reaching French Polynesia in the eastern Pacific.

Reaching land here was a matter of extraordinary luck.

Unlike Fiji, there are no bats in French Polynesia,

no frogs and only a handful of lizards.

The most successful travellers were the long-haul fliers -

sooty terns.

Incredibly, they can stay in the air for four years without landing...

but to breed, they must return to nesting sites on remote islands.

And when they do, they introduce new life.

Sticky or barbed seeds fasten on to their feathers and hitch rides across oceans.

On some islands, 75% of plants arrived with the birds.

Seeds are even carried in the stomachs of some birds.

As if getting a lift wasn't enough for these seeds,

seabirds also provide them with something else.

The seafood these birds bring back to the islands

is turned into nutrient-rich guano - plant fertiliser.

And there's enough of it to transform barren coral atolls into fertile groves.

There is one plant castaway that needs no help in finding new land -

a plant that has probably done more

to change the fortunes of island life than any other,

and one of the greatest long-distance travellers of all time.

The humble coconut.

Its seed is a compact survival capsule.

Buoyant and filled with food for germination,

it can survive for up to two months at sea...

long enough to float from one remote island to the next.

On arrival, it lays down roots into bare sand

and taps into the reservoirs of underground freshwater.

Without coconuts, most of the tropical islands in the South Pacific

would have remained uninhabitable for both animals and people.

There is one set of islands, however, that is so remote

that even the coconut couldn't reach it.

North of the equator, 2,500 miles from the nearest landmass of North America,

lies the most isolated chain of islands in the world - Hawaii.

The longest archipelago in the Pacific,

Hawaii consists of over 100 ancient volcanic islands

stretching for 2,000 miles.

Yet it is so remote that less than 500 kinds of animal settled here

in 30 million years.

But for those who did make it to this lush and fertile land,

the world was their oyster.

Here, coconut palms have been replaced by giant tree ferns

standing over seven metres tall.

From the 13 kinds of spider that made it here,

over 100 new species evolved - like the happy-face spider.

From just one species of fruit fly came over 1,000 others.

And here, caterpillars were free to become carnivores.

Hawaii's 20 surviving species of honey creeper

also evolved from just a few individuals.

Compared to seabirds, honey creepers are poor fliers.

So how did the ancestors of these forest birds

and Hawaii's other castaways get here?

The answer may be blowing in the wind.

Even the gentlest breeze can have a huge impact.

Tree ferns stir and release their lightweight spores.

Thermal updrafts can carry the spores 30,000 feet into the jet stream.

And there are even animals designed to ride these high-altitude air currents.

Near-weightless spiderlings are expert ballooners,

catching the wind with their gossamer threads.

Like spores, they, too, can hitch a ride on the jet stream.

Enduring temperatures of minus 30 degrees centigrade,

a spider can cross the breadth of the Pacific in a matter of days.

Larger insects and animals need more than a breeze to carry them away.

Vast tracts of warm water are a perfect environment for cyclones.

Over half the cyclones on the planet - around 30 a year -

form in the Pacific Ocean.

Heated by the warm tropical sun,

water evaporates and forms massive thunderstorms,

fuelling a whirling vortex...

in some cases up to 500 miles wide.

When they collide with islands, they unleash their fury.

Winds in excess of 100mph can uproot a forest.

Large insects can be sucked up into the sky...

so why not birds, bats and lizards?

In fact, all these creatures are known to have been carried

hundreds of miles out to sea by cyclones.

When the storm subsides, most will meet a watery grave.

But a very, very lucky few will land on firm ground,

and from these survivors, a whole island dynasty may be born.

No matter how remote the Hawaiian islands are, or how hostile,

there is one creature that has reached almost all of them.

The mourning gecko.

It is the ultimate castaway...

the marathon winner on the long journey from New Guinea.

Incredibly, the female mourning gecko has done away with the need for a mate.

Instead, she simply produces eggs that need no fertilisation.

So one single female washed up on an island could start a whole population.

Along with this extraordinary ability,

these thick-skinned and salt-resistant geckos

could also survive long sea passages on rafts,

and even the force of cyclones.

But there is more to the gecko's story than this.

Less than 2,000 years ago,

something happened that was to revolutionise

the spread of plants and animals.

Taking to their sailing boats once more, descendants of the Lapita

left the central Pacific and set off again in search of new lands...

into the great unknown.

As pioneers, they took everything they would need to start their lives afresh.

Livestock.

Plants for cultivation.

Even the coconut.

But they would also have taken a long list of stowaways...

like the mourning gecko.

This lizard was just one castaway

which no longer had to rely on its stamina and luck to reach new lands.

It could now hitch a free ride.

In a series of epic voyages, the descendants of the Lapita,

the people we now call the Polynesians,

succeeded in colonising the far corners of the South Pacific -

from Hawaii to New Zealand, even to Easter Island,

nearly 7,000 miles east of New Guinea.

In doing so, animal castaways now reached new islands at a rate never seen before,

changing the nature of the South Pacific for ever.

For years, the Solomon Islands have been home

to legends of massive saltwater crocodiles.

Separating fact from fiction, the goal of the Castaways team

was to capture evidence that huge crocs WERE living on these little-known islands.

Braving the high seas, cameraman Wade Fairley

made the 1,000-mile crossing from Australia to the Solomons.

The Solomons are a chain of almost 1,000 remote islands.

Wade would need the freedom of a boat

to stand a chance of finding these mysterious crocodiles.

Caught some dinner.

Joined by producer Mark Brownlow,

they started their two-week expedition in the Western Provinces.

With few scientific leads, they would have to rely on local knowledge.

The crocodile tales began, interpreted by Wade, a fluent pidgin-speaker.

WADE: Oh, yeah?

MAN: Sacred crocodile.

- And he's got no tail? - No, no tail.

Following the tip-off of the four-metre tailless crocodile,

they decided to track him down that night, when these reptiles are most active.

To minimise disturbance,

they scanned the mangroves with infrared light, invisible to crocodiles.

Well, that's remarkable.

I would have guaranteed that we were onto something here,

but we haven't seen one crocodile.

Ooh.

Aside from a mysterious splash,

the only confirmed sightings were juveniles.

Where were the adults?

Over the next two nights,

the tailless croc continued to elude them.

It was time to move on.

70 miles to the east,

they reached the island of Liapari, in the central Solomons.

We're hoping to film some crocs in a freshwater lake,

which we... we hear is "stacka".

The big question is,

is there going to be stacka too much crocodiles or stacka little bit?

Once more, they were regaled by stories of giant crocodiles.

You say the old man, he talk to the crocodiles?

I try to explain it.

He knows the crocodiles, he's got some, you know, magic...

- Magic. - that they can work together.

But there were words of warning.

Unnerved by tales of man-eating crocs,

Mark and Wade headed off in search of the crocodile lake.

On the way, they passed some sinister sights.

A skull shrine -

evidence of the island's head-hunting past.

- So this sacred place with the skulls... - Yeah, yeah.

is guarded by the crocodiles of the lake?

Reaching the lake, Wade and Mark edged as close as they dared.

Would they see any of these legendary crocs?

We've got no idea how big these saltwater crocs are,

but we don't dare get any closer - it could be too dangerous.

That afternoon,

Wade got his first shot of a modestly sized, two-metre crocodile.

Despite camping out for three days, they failed to spot anything larger.

Whatever big crocs were out there did not materialise.

It was beginning to feel like a wild croc chase,

but they decided to push on to new islands.

A hundred miles east, they dropped anchor in Marovo Lagoon.

Wade explored the maze of mangroves - prime crocodile country.

That was rather sobering advice. I was paddling quite close to the bank -

he told me to come back out into the middle

because that's where the crocodiles are.

They called in at the local village to ask their advice on where to stake out,

discovering worrying signs of big crocodiles at large.

Only a large crocodile would be capable of inflicting such a horrific injury.

The village chief confirmed

that attacks on both the villagers and their livestock were on the increase.

With displaced crocodiles now encroaching on villages,

there appeared to be a growing conflict.

WADE: Do you think he's a danger?

♪ Thank you for your love... ♪

To learn more about these problem crocodiles,

the team headed to the Solomons' capital, Honiara -

headquarters for the international peacekeeping force

policing both the islanders and their crocodiles.

We've had some tragedies here where people have lost their life or been injured.

Not nice at all, and that worries us,

but I think that we have a system to manage that

inasmuch that we've got this team of people that are skilled

and well trained to go and destroy them.

Not that we really want to do that, but when it's asked for, we'll go and do it.

So the large crocodiles have good reason to be camera-shy.

Hunted down, only the wiliest crocs survive.

It seemed that the team's best chance was away from people.

The peacekeepers had recommended

the wild and mostly uninhabited coast of Guadalcanal.

On the tip-off of a large crocodile seen laying up on this lonely stretch of beach,

Wade set up his camera hide one last time...

and the long wait began.

It's almost dawn. It's been a long, long, long, long night. Absolutely nothing.

All I've seen is a dog and some crabs.

I can only figure that the crocodile knows I'm here.

He's a big, old, smart bugger, for sure,

and if he's grown that big,

it's obviously from being smart,

and he's outsmarted me.

Yet it was at dawn, after a three-day vigil,

that an impressive, three-metre crocodile finally appeared.

In the end, Wade only managed

to record a few minutes of footage of these camera-shy giants.

But these images were proof of the existence

of large saltwater crocodiles in the Solomons -

the last living legends in the South Pacific.