CHORUS: ♪ Teach your children well ♪ They love ♪ And know they love you.

NARRATOR: The South Pacific.

Lagoons that hint at paradise.

Magnificent coral reefs that tease and delight the dreaming corners of our minds.

This is the world as we wish it could always be.

(man sings foreign phrase) (men repeat phrase) (men singing) (man sings foreign phrase) (men repeat phrase) (men singing) NARRATOR: In this great carnival of life, thousands of colorful characters coexist.

Diversity strengthens the coral reef.

The more species, the more survival systems.

Coral reefs have been going strong for 60 million years.

Some corals sway like flowers in a breeze, others masquerade as stones, but all corals are animals.

These underwater playgrounds are built by hard corals, which produce limestone and turn it into homes.

Stacked one on top of the other, millions of coral homes gradually form a gigantic reef.

How wonderful that the largest living structures on Earth are built by tiny animals.

(man singing in foreign language) Coral reefs protect nearly all tropical coasts standing between islanders' homes and violent seas.

When we're injured, doctors use calcium carbonate from coral to mend our broken bones.

When we're sick, chemical compounds from the reef may restore our health.

No place on Earth holds greater potential for medical cures.

Reefs feed us.

Over 300 million people rely on fish from reefs.

RUSI VULAKORO: For Pacific Islanders like me, our coral reefs are as necessary as the air we breathe.

(chorus singing) NARRATOR: Rusi Vulakoro, a native of Fiji, has always lived close to the sea.

(speaking Fijian) RUSI: For centuries, my ancestors were careful not to overfish, so our reef was healthy.

But this year, something happened... something terrible.

(woman sings) RUSI: A blanket of death settled over the reef.

What was killing our reef?

I made up my mind to find some answers.

I decided to reach out to some of my dive partners around the world.

NARRATOR: Howard and Michele Hall have spent 30 years exploring and filming reefs.

Their underwater photography is world renowned.

When Howard and Michele got Rusi's message, they were in the mountains, far from the reefs they love.

♪ Carry me ♪ Carry me, yeah ♪ Carry me ♪ Above the world... HOWARD: All during that flight, I kept wondering what we could do to help Rusi.

Then I realized that our friend Richard Pyle might know what to do.

He's a marine biologist.

RICHARD: These kinds of problems are happening all across the world, really, uh, the Red Sea, East Africa, the Maldives, Philippines-- we're seeing these kinds of problems showing up at unprecedented rates.

MICHELE: Richard showed us how coral reefs are dying at an alarming rate all around the world.

RICHARD: You also get changes in temperature... MICHELE: Ocean warming is the major cause.

Richard urged us to document the coral reefs on film for science before they disappear.

We knew that the IMAX camera, with its incredible clarity was the best way to do this.

HOWARD: Open it all the way up to f-2.8.

Our mission was clear... That's wonderful.

Thanks so much for your help.

HOWARD: Bring back images that would give scientists insights into why Rusi's reef was dying.

We needed to compare Rusi's reef to other reefs all across the South Pacific, starting with the largest of them all-- the Great Barrier Reef.

(bell dinging) (flute playing bright melody as chorus sings along) HOWARD: The prospect of diving coral reefs all across the South Pacific was a bit like a dream come true.

We would make hundreds of dives and some of these would be deeper and more dangerous than anything we've done before.

It would be our most important expedition in our 30 years of diving together.

NARRATOR: Parts of the Great Barrier Reef have been protected from overfishing for two decades.

The first goal of this ten-month expedition was to see how well that protection really worked.

(light, mellow island music playing) HOWARD: When I first dove here 22 years ago, these giant clams were not here.

They'd been long fished out by commercial fishermen.

Today, we've seen 12 giant clams, and that's a great sign.

That means that this reef is bouncing back.

A local marine biologist named Tracey Medway led us to the giant potato cod.

They're called potato cod because they have these splotchy potato-shaped markings on their sides.

TRACEY: Throughout most of the South Pacific, the really large fish have been wiped out by fishermen.

Potato cod thrive here only because of the laws that protect them.

MICHELE: These vegetarian convict tangs protect the reef, nibbling away seaweeds that smother corals.

If too many of these kinds of fish are removed, corals will die.

That's why overfishing destroys reefs.

TRACEY: We often don't realize how two species benefit each other until one of them disappears.

NARRATOR: Just as fish protect the reef, coral offers homes and hiding places for the fish-- anything from a simple shack to a custom dream home.

♪ I'll light the fire ♪ You place the flowers in the vase that you bought today... ♪ NARRATOR: Gobies often share a home with bulldozer shrimp.

Whenever he ventures out of the burrow, the shrimp keeps at least one antenna on the goby.

The goby gets an impeccable burrow to live in without lifting a fin and the very near-sighted shrimp gets a bodyguard.

With the flick of its tail, the goby warns the shrimp of approaching predators.

♪ Our house is a very, very, very fine house ♪ ♪ With two cats in the yard ♪ Life used to be so hard ♪ Now everything is easy 'cause of you ♪ ♪ I'll light the fire ♪ While you place the flowers ♪ In the vase that you bought today... ♪ MICHELE: This 100-year-old coral makes a nice dentist's office for potato cod.

A small fish, a cleaner wrasse, swims right into the cod's mouth to feed on parasites.

Mmm.

NARRATOR: The cod gets groomed... and the wrasse gets dinner.

Partnerships like this seem to require mutual trust.

Lots of trust.

NARRATOR: Cat Holloway, a coral researcher, joins Michele to study "interspecies communication."

♪ So we change partners ♪ Time to change partners ♪ We must change partners... MICHELE: I was afraid I was going to inhale and maybe swallow it, but I didn't.

It just tickled and pinched a little bit.

I've studied animal behavior for so many years; this was-- this was different.

This was a chance for me to actually be part of it.

NARRATOR: Cooperation between species sustains life here, but sometimes it's almost invisible.

HOWARD: The coral's most important partners are tiny, microscopic algae that actually live inside the coral animal's tissues.

This is the brain coral, right?

These helper algae use sunlight to produce sugar-- the primary food source that gives corals the energy to build reefs.

NARRATOR: Most corals cannot survive without helper algae.

But worldwide, abnormally warm seawater threatens this partnership.

HOWARD: Time-lapse photography can show us how, in just one week, a change of two degrees centigrade drives the algae out.

Without its main food source, the coral bleaches a ghostly white.

If the algae don't return, the coral starves.

MICHELE: Here in Australia, we went to some places that we'd been to 20 years before, and I was surprised to see that some of the reefs are so damaged, because of ocean warming.

HOWARD: Our Australian survey gave us a baseline for understanding what was going wrong at Rusi's reef, 2000 miles away, in Fiji.

♪ Got out of town on a boat ♪ Goin' to southern islands ♪ Sailing a reach before a following sea ♪ ♪ She was making for the trades on the outside ♪ ♪ And the downhill run to Papeete ♪ ♪ Around ♪ I have been around the world ♪ ♪ Looking ♪ Lookin' for that woman-girl ♪ Who knows, who knows ♪ Who knows love can endure... ♪ HOWARD: When we got to Fiji, it didn't take five minutes to reconnect with Rusi.

The friendliest hawkbill turtle I've ever seen.

Ah, yes, it was.

RUSI: Howard made me smile again.

HOWARD: Michele and I were eager to help Rusi, but first, we had to pay our respects to local tradition.

(chanting) RUSI: Before outsiders can dive at my home island, the elders must grant permission.

My people have always limited fishing.

This tradition of reef conservation has worked well for centuries-- till now.

First, I wanted Howard to see my village reef as it used to be.

(men singing) HOWARD: The reef looked great, with plenty of small fish, but we didn't see nearly as many big fish as we did in Australia.

And that worried me.

RUSI: The time had come.

I took Howard and Michele further down the reef.

MICHELE: I wondered where all the animals had gone.

These reefs are dying.

It all just makes me really sad.

HOWARD: Seeing so much of this reef destroyed, we realized that Rusi's reef may be what all coral reefs look like in 30 years.

RUSI: Our reef used to be home to so many creatures.

But now, they're almost all gone.

MICHELE: After seeing all the destruction, though, I saw an octopus.

Octopus make like a tent with their body.

They put out their eight arms and actually trap shrimps and crab that live on the reef.

He had obviously figured out how to survive.

Not many reef dwellers are able to do that.

RUSI: For islanders who survive by fishing, the death of the reef has really hit us hard-- especially when you have children to feed.

HOWARD: But what killed Rusi's reef?

Foreign fishing fleets have overfished these waters and thermometers tell us that the ocean is two degrees warmer than normal.

RUSI: I found more bleached coral and no big fish.

But I had a hunch that ocean warming and overfishing were not the only problems.

NARRATOR: Ten miles inland, when tropical rain forests were cut down, the river turned muddy with silt.

(chorus sings in native language) Two rivers merge-- one with logging upstream, one without.

There's only one place for all that sediment to go.

(chorus sings) MICHELE: At the mouth of the river, silt blocked the sunlight that the coral needs for growth.

NARRATOR: Rusi's reef had been hit by a combination of stresses-- ocean warming, overfishing and siltation.

Corals may fight off one threat, but three at once proved too much.

RUSI: Now I understood the problem better.

But what could I do?

Howard thought a healthy reef might give us some answers.

We set course for another island.

HOWARD: There, we joined up with Jean-Michel Cousteau, who's the son of the legendary explorer.

Jean-Michel comes to Fiji every year to help marine biologists like Maria Joao Rodriguez monitor coral reefs.

JEAN-MICHEL: We guided Howard and Michele to a nearby reef where siltation is not a problem-- thanks to mangrove trees.

Their roots trap silt, protecting the reefs.

MARIA JOAO: Many fish use mangroves as a nursery to protect their young.

♪ The river seems dreamlike... ♪ RUSI: My fellow Fijians have set aside these beneficial mangroves as part of a marine preserve, making the reef offshore a wonderland-- healthy, beautiful and strong.

This is the way I want my reef to be.

JEAN-MICHEL: Tropical coral reefs are found worldwide.

Fiji is the soft coral capital of the world.

(chorus sings) HOWARD: Corals are beautiful, but they're also beneficial.

Chemical compounds from coral reefs have been reproduced in the lab to provide relief from chronic pain, ease childbirth, and even extend the life of AIDS patients.

RUSI: Corals share their food-- in fact, many of them share the same stomach.

NARRATOR: When the current picks up speed, time-lapse photography shows how these soft corals inflate like balloons to trap passing morsels.

RUSI: On a healthy reef like this, you see so many different creatures.

MICHELE: We prefer not to approach the animals.

It's better if they come to us.

NARRATOR: This distant cousin of the cobra can kill a person with its venom in a matter of minutes but they rarely bite humans.

Michele is counting on that.

RUSI: We learn a lot about a reef from its animals-- and so do the children.

There's more to the reef than meets the eye.

(yelling exuberantly) ♪ Teach your children well ♪ Their father's hell did slowly go by... ♪ JEAN-MICHEL: Observation is the first step in science.

Who would notice that yellow damsel fish guard their tiny eggs before they hatch?

RUSI: Or that the sea cucumber filters waste, leaving the reef cleaner for all?

Some of the finest marine biologists are Fijians.

We could have a budding scientist in our midst.

♪ Don't you ever ask them why ♪ If they told you, you would cry ♪ ♪ So just look at them and sigh ♪ ♪ And know they love you.

JEAN-MICHEL: We've learned that we don't inherit the Earth from our parents-- we borrow it from our children.

NARRATOR: Children love to spot fish they've never seen before.

That same thrill of discovery drives many scientists, like Richard Pyle.

I catch little fish-- little fish for science.

HOWARD: Richard Pyle calls himself a "fish nerd."

He studies fish on the deepest parts of coral reefs.

RICHARD: The deeper down we go on a coral reef, the less we know.

I want to find out what lives there.

HOWARD: You can't get a true picture of a coral reef if you only look at part of it.

But deep dives can be really dangerous.

Even using special breathing devices, we can still get a fatal disease called "the bends."

MICHELE: I nearly lost Howard on a deep dive only two months ago.

He had a bad case of the bends.

It could have killed him.

HOWARD: To stop the progression of the illness, I began breathing pure oxygen, but it didn't seem to help.

I was losing all feeling in my right leg.

MICHELE: One of the terrifying moments for me was actually seeing him stumble.

(voice breaking): I just thought, "This can't be happening."

NARRATOR: Michele rushed Howard to the hospital, hoping that a specially pressurized chamber might halt the illness and save his life.

MICHELE: Thank God for the communication system, because at least then I could talk to him.

Howard survived, but his close call was on my mind as we prepared for a dive to 350 feet.

NARRATOR: The next day, on the deep dive, Howard and Richard would face pressures nearly twelve times greater than normal, but they're expert divers, and there's much to learn by exploring regions where so little is known.

♪ MICHELE: Support divers attach safety tanks to a lifeline every 50 feet.

♪ Into the darkness ♪ Soon you'll be sinking ♪ What are you doing?

♪ What can you be thinking?

♪ All of your friends ♪ Have been trying to warn you ♪ ♪ That some of your demons ♪ Are trying to drag you ♪ Away ♪ Into the darkness ♪ Into the darkness ♪ Into the darkness ♪ Away... RICHARD: One hundred feet.

MICHELE: Roger, one hundred feet.

HOWARD: As we descend, too much oxygen is bad.

Too little is worse.

Both can kill you.

Okay.

HOWARD: The safety divers go down as far as they can and stop.

After that, we're on our own.

As we drop down the reef wall, it gets darker and colder.

And, in a way, we're going back in time.

At 200 feet, we pass limestone deposits that were laid down 20,000 years ago, back when this was the top of the reef.

RICHARD: Michele, we're at bottom, 350 feet.

HOWARD: At 350 feet, we enter the twilight zone.

It's sort of spooky but wonderful to look around at a reef that no one has ever laid eyes on before.

It's starting to get interesting.

RICHARD: We don't see any of the corals that rely on sunlight.

Instead, we see fan corals and whip corals.

This reef community definitely appears to be thriving.

NARRATOR: In his quest to find out what lives down here, Richard can only bring a few specimens back to the surface, to be documented for science.

RICHARD: Looking around, I see at least a dozen new fish species that I've never seen before.

I doubt anyone's ever seen them before.

NARRATOR: Scientists like Richard are mapping the web of life that we are all part of.

Each new fish Richard finds holds millions of years of genetic engineering for medical research.

(camera clacking and whirring) NARRATOR: Then the intense water pressure caused the primary camera to malfunction.

MICHELE: I was glad that Howard called an end to the dive.

We hope that Howard's images will let scientists explore a reef that they might never be able to dive on their own.

HOWARD: It's not every day you get to witness the discovery of a new species of fish.

MICHELE: Wow!

RICHARD: You see that red one with the long tail?

Yeah!

That's the one I'm really excited about.

That's definitely new.

That's a new one?

Oh, yeah.

HOWARD: Oh, I see those all the time.

(all laughing) (lively island music playing) RICHARD: Until quite recently, the deep coral reefs were this big, dark void on our map of life.

But each new discovery leads us to new connections.

This may seem like just some insignificant little red fish, but it's a very important piece to the biodiversity puzzle.

As soon as I saw it, I knew it was something different.

NARRATOR: The months of hard work in Fiji paid off.

RUSI: One more time, everybody.

NARRATOR: Rusi has seen firsthand how corals can thrive when reefs are protected.

He is now ready to return to his home island.

RUSI: My fellow Fijians have shown me how to set up a marine preserve, protect the mangroves, and even curb logging operations.

I really want to get started.

HOWARD: Here in Fiji, we've seen some amazing reefs, but we've also seen a lot of coral damage.

The siltation we saw at Rusi's reef led us to our next question: Is closeness to shore a major risk factor for corals?

French Polynesia is the perfect place for answering this question.

(ship horn blows) ♪ ...Sailing a reach ♪ Reach ♪ Before a following sea ♪ Following sea ♪ On the downhill ♪ On the down ♪ Run to Papeete... NARRATOR: In French Polynesia, Howard and Michele started with the heavily populated islands of Tahiti and Mo'orea, where the reefs are close to shore.

But with only six weeks left in the whole expedition, Howard had to get the big picture fast.

(singing "Teach Your Children Well" in French) HOWARD: I'm used to hang gliders.

I'm used to flying around in contraptions like this.

But there's still something not quite right about an engine that will fit in my backpack.

(singing continues) Mo'orea is sort of like Rusi's island.

The coral here is very sensitive to siltation and pollution because the reefs are very close to shore.

After checking out the north side of Mo'orea, we head across the mountains to survey the south coast.

♪ Ah... go back.

Even near towns, we didn't spot much reef damage.

NARRATOR: Coastal development puts reefs in jeopardy-- siltation, pollution, and the loss of mangroves are all serious risks.

But resorts like this prove that respecting the environment is good business because tourists avoid damaged reefs.

HOWARD: Our flight over Mo'orea just gave us a first impression.

So with time running out, I turned to Reef Check, aboard the survey boat, the "Quiksilver Crossing."

NARRATOR: Reef Check has over 4,000 sport divers in 60 countries monitoring the health of coral reefs.

MICHELE: We asked Reef Check volunteers to check the coral damage here at Mo'orea to find out if the reefs closest to shore are the most severely damaged.

(drums play, men's chorus sings) NARRATOR: From the air, it's clear how these volcanic islands formed, and how coral reefs formed around them.

The steepest, youngest islands-- Tahiti and Mo'orea-- stand tall.

These islands have not eroded and subsided much, so the coral reef ringing them is not far offshore.

Bora Bora is middle-aged.

The volcano has subsided and eroded somewhat, and the reefs are farther from shore.

The final stage is this flat doughnut of an island called an atoll.

The volcano has completely subsided back into the sea, leaving a ring of coral which once circled a tall mountain.

The team headed for the second-largest atoll in the world-- Rangiroa-- to survey the remotest reefs in French Polynesia.

HOWARD: Ten years ago, a cyclone wiped out most of Rangiroa's coral.

But storms are natural events and coral reefs do recover from them, as long as human impacts don't interfere.

Here, the corals seem small but healthy.

MICHELE: Right away, we saw two male parrot fish fighting over territory.

This was a sign of a large and thriving fish population.

But why haven't we seen the huge schools of gray reef sharks Rangiroa is so famous for?

Their absence is not necessarily a danger sign for corals, but it could signal an imbalance in the whole reef ecosystem so finding the sharks became our main goal.

HOWARD: We searched the shark's favorite hangouts, but they didn't seem to be home.

We used caution, because one thing you don't want to do is catch a gray reef shark by surprise.

If the sharks are out roaming the reef in shallow water, the quickest way to spot them is from the Ultralight.

Throughout the Pacific, whole populations of sharks have been wiped out by commercial fishermen.

Gray reef sharks are especially vulnerable and that's what worried me.

The aerial search for sharks turns up nothing, and we're running out of time.

But there's one last place to look-- Tiputa Pass.

Here the current just screams.

(current rumbling) HOWARD: Hundreds of startled sharks are hanging out like a street gang in this little canyon.

We're being swept right into them and there's nothing we can do about it.

(drums playing, men calling) (chorus sings) HOWARD: Could they be mating?

This is when you try very hard not to look like a shark.

I've had two friends badly bitten by gray reef sharks.

The most social of all sharks, grays tend to swim in tight groups.

I've been diving for 35 years, but I've never seen the likes of this.

There must have been 300 sharks in this school.

And that's a healthy number.

This big school doesn't close the book, but it is a favorable sign for the health of this reef ecosystem.

We party with the sharks for nearly an hour, knowing that, on the way home, we'll have the current at our backs so we can go with the flow.

(upbeat guitar intro playing) ♪ Lookin' at the world ♪ Through the sunset in your eyes ♪ ♪ Trying to make the train to clear Moroccan skies ♪ ♪ Bugs and pigs and chickens call ♪ ♪ Animal carpet wall to wall ♪ American man is five foot tall and you ♪ ♪ Sweeping cobwebs from the edges of my mind ♪ ♪ Had to get away to see what we could find ♪ ♪ Hope the days that lie ahead ♪ ♪ Bring us back to where they've led ♪ ♪ Listen up to what's been said to you ♪ ♪ Don't you know we're riding on the Marrakech Express?

♪ ♪ Don't you know we're riding on the Marrakech Express?

♪ ♪ They're taking me to Marrakech ♪ ♪ All on board... HOWARD: For 10 exhausting but magical months, Michele and I explored some of the most magnificent coral reefs on Earth.

During that time, our concern for corals grew into a shared passion.

(men singing in native language) RUSI: My people look at the reef and we don't want to believe such a place could be gone forever.

My friends, Howard and Michele, have given me new tools to heal my village reef.

MICHELE: Howard's love for the reefs nearly cost him his life.

But after making more than 500 dives, we came back with some really powerful images.

One image I can't get out of my mind is that lone octopus, crawling through the rubble.

Soon, it may not have a home.

No one sets out to kill a beautiful thing but when a reef dies, billions of living things die.

Corals appear to be dying faster than normal, and the trend is rapidly accelerating.

Most living coral reefs, as we know them today, could be gone in 30 years.

If that happens, then something inside of me will die, too.

HOWARD: After all the coral reefs have given us, more and more people are now returning the favor.

They're supporting leaders who fight global warming, joining teams like Reef Check, and getting involved.

RICHARD: We may have greater potential of finding new medicines on coral reefs than any other environment on Earth.

To save them is really saving ourselves.

-♪ Don't -♪ Don't ♪ Don't ever ask them why -♪ Why -♪ Ask them why ♪ You will cry ♪ So just look at them and sigh... ♪ RUSI: It takes a long, long time to build a coral reef, step by step.

The reefs survive on partnerships.

And the most important partners the corals have are you and I.

(singing "Teach Your Children Well" in French) (song continues)