[ROLLING THUNDER] ♪ ♪ ♪ ♪ NARRATOR: AUSTRALIA'S GREAT BARRIER REEF STRETCHES ALMOST 1,500 MILES.

IT'S THE WORLD'S LARGEST REEF SYSTEM AND ONE OF THE MOST COMPLEX ENVIRONMENTS ON OUR PLANET.

THE RHYTHMS OF LIFE OSCILLATE FROM BREATHLESS HEAT TO VIOLENT STORMS.

AT THIS TIME OF YEAR, HURRICANES BREW OFF THE COAST READY TO WREAK HAVOC ON BOTH REEF AND RAINFOREST.

REPORTER: A CATEGORY 5 CYCLONE HAS UNLEASHED ITS FURY ON NORTH QUEENSLAND.

NARRATOR: BUT NEW FORCES ARE ALSO INTENSIFYING.

PILOT: THEY'RE FISHING, UM WITHIN A GREEN ZONE WHICH IS AN OFFENSE.

IT'S ABOUT PROTECTING THE GREAT BARRIER REEF.

NARRATOR: HOW WILL THE REEF RESPOND TO THE THREATS THAT CHALLENGE ITS DELICATE BALANCE?

[THUNDER] NARRATOR: IT'S SUMMER IN NORTH QUEENSLAND, BUT NOT AS YOU KNOW IT.

THE LOCALS CALL IT THE WET SEASON.

IT'S A TIME WHEN THE TROPICS HEAVE WITH ENERGY.

[LOUD RAIN] THE RAIN FALLS HARD.

RIVER RUN-OFF AND OCEAN CURRENTS ARE PUMPING NUTRIENTS INTO THIS SUPER-CHARGED ECOSYSTEM.

THE BASE OF THE FOOD CHAIN IS PRIMED.

HUGE SCHOOLS OF BAIT FISH NOW GATHER TO FEED ON PLANKTON AT JUNCTIONS OF CURRENT.

PREDATORS FROM ALL OVER THE PACIFIC OCEAN CONVERGE ON THE REEF TO TAKE ADVANTAGE OF THIS TIME OF PLENTY.

A SCHOOL OF SAILFISH WILL TAKE THIS ONE.

WORKING TOGETHER, THE HUNTERS MOVE TO CONTROL THE BAIT FISH.

IN THE BATTLE BETWEEN PREDATOR AND PREY, BOTH HAVE DEVELOPED EXTRAORDINARY ADAPTATIONS.

THE BAIT FISH MOVE IN TIGHTLY COORDINATED SCHOOLS TO DAZZLE THE PREDATORS.

THE SAILFISH HAVE EVOLVED LONG BILLS TO SLASH THROUGH THE BAIT BALLS AND PICK OFF THE INJURED.

AS THEY PUSH THE BAIT BALL TO THE SURFACE, EYES IN THE SKY ARE WAITING.

SEABIRDS STUFF THEIR GULLETS WITH ENOUGH FISH FOR THEMSELVES AND THEIR CHICKS.

BY JANUARY, COLONIES ARE FULL OF ANXIOUS PARENTS HOPING THEIR YOUNG WILL FLEDGE BEFORE THE WEATHER GETS TOO WILD.

BUT SO FAR, NO STORM, AND THE TEMPERATURE IS SOARING.

ON REMOTE RAINE ISLAND, RESEARCHERS ARE BATTLING 105-DEGREE HEAT... AND BLISTERING SUN.

THEY'RE HERE TO CHECK THE NESTING ON ONE OF THE MOST PROTECTED ISLAND SANCTUARIES IN THE WORLD.

MARK: UP THE TOP?

WARWICK: ALL THE WAY TO THE TOP, LET'S DO IT.

MARK: YEAH.

SO, WARWICK, IF YOU WANT TO ADD ANOTHER 43 RUFOUS NIGHT HERONS.

WARWICK: OKAY, MARK.

MARK: GEEZ, THERE IS A LOT OF FRIGATES OUT THERE ISN'T IT?

WARWICK: THERE'S A LOT OF, YEAH.

I HAD A COUNT IN THIS BASIN OF 200.

MARK: WHAT WE HAVE NOTICED IS THAT SOME OF THE SEABIRDS ON RAINE ISLAND HAVE UNDERGONE SOME PRETTY SIGNIFICANT DECLINES.

NEARLY ALL THE SEABIRDS THAT WE SEE HERE RELY ON THE OCEAN FOR FOOD, SO THEY'RE FEEDING ON FISHES, LIKE, YOU KNOW, SARDINES AND HERRING, THE SORT OF SCHOOLING FISH.

AND WHAT WE THINK IS HAPPENING IS THAT BECAUSE OF OVERFISHING OF THE PREDATORS OF SOME OF THESE SCHOOLING FISH, THERE'S NOT THE BIG FISH AROUND NOW TO PUSH THOSE BAIT BALLS TO THE SURFACE, AND THAT MEANS THAT THESE SORTS OF BIRDS CAN'T ACCESS THEM AS EASILY.

SO IN SOME YEARS, UM, THEY DO VERY, VERY POORLY BECAUSE THERE'S JUST NOT THE FOOD FOR THEM.

WE NEED TO BE VERY MINDFUL OF THE FACT THAT HUMAN BEINGS AREN'T THE ONLY ANIMALS THAT RELY UPON THE FISH FOR PROTEIN.

THESE POPULATIONS WILL COLLAPSE IF THEY CAN'T GET ADEQUATE RESOURCES.

NARRATOR: WITH A BELLY FULL OF FOOD, A BOOBY RETURNS FROM A DAY'S FISHING ON THE REEF.

CLOSE TO SHORE, A FRIGATEBIRD IS WATCHING.

HE'S THE BIGGEST SPECIES HERE, BUT HE DOESN'T ALWAYS FISH FOR HIS FOOD.

HE PREFERS TO STEAL IT.

SHE TRIES TO DODGE THE AERIAL PIRATE.

BUT HER EVASIVE MOVES ARE NO MATCH FOR THE FRIGATE'S SPEED AND POWER.

THE ONLY OPTION IS TO REGURGITATE MID-FLIGHT.

SAVING HER LIFE BY GIVING HER LUNCH TO THE ISLAND BULLIES.

YET EVEN THEN, THE BATTLE ISN'T OVER.

THE FRIGATES NOW FIGHT AMONGST THEMSELVES FOR SCRAPS OF BOOBY VOMIT.

IT'S A SCENE THAT PLAYS OUT EVERY AFTERNOON AS THE BOOBIES RUN THE GAUNTLET TO THEIR NESTS.

A BROKEN WING MEANS THIS BOOBY'S FISHING DAYS ARE OVER.

AS THE SUN SETS, A RARE MIRAGE APPEARS, A GREEN FLASH ON THE HORIZON.

IT ONLY LASTS A SECOND OR TWO AND SIGNALS THE SEA IS WARMER THAN THE AIR.

PHANTOM COLORS THAT ARE HIDDEN UNLESS YOU KNOW WHERE AND HOW TO LOOK.

OUT IN THE CORAL SEA, DIVE INSTRUCTOR PADDY CALDWELL IS ABOUT TO TRY JUST THAT.

HE'S LOOKING AT THE SUBMARINE WORLD IN A WHOLE NEW LIGHT.

JON: YOU LOOK ABSOLUTELY RIDICULOUS THERE, UM, PADDY.

NARRATOR: WITH THE HELP OF UNDERWATER CINEMATOGRAPHER JON SHAW, HE'S GONNA DIVE USING BLUE LIGHTS TO TRY AND SEE THE REEF FROM A FISH'S PERSPECTIVE.

PADDY: OH, GEE, GIVE YOU A BLINDING ANYWAY, MINE'S PRETTY GOOD.

IT'S COMPLETELY SURREAL.

IT FEELS LIKE IT SHOULDN'T BE LIKE THIS.

THERE'S A WHOLE OTHER WORLD WITHIN THE WORLD THAT I SEE OUT THERE.

NARRATOR: LOOKING THROUGH YELLOW GOGGLES, UV LIGHT REVEALS A WORLD ONLY FISH CAN APPRECIATE, TAKING US DEEPER INTO THIS SECRET REALM.

MANY OF THE ANIMALS ON THE REEF EMIT VIVID FLUORESCENT COLORS BEYOND OUR VISUAL RANGE.

AS WE SHINE A UV LIGHT ON THIS WORLD, WE SEE NOT ONLY HIDDEN COLORS BUT ALSO HIDDEN CREATURES.

PADDY: I SAW WHOLE CORAL FULL OF MICROSCOPIC LITTLE CRABS RUNNING ROUND THE PLACE, AND I THEN DECIDED TO LIFT THE FILTER OFF MY MASK AND I PUT NORMAL LIGHT ON AND I COULDN'T SEE THEM.

THEY WEREN'T THERE.

I LOOKED WITH THE BLUE LIGHT AGAIN, AND THERE THEY WERE, THERE WAS HUNDREDS OF THEM, AND THEY WERE ALL OVER THE PLACE, WHICH MEANS THERE'S SOME ANIMALS OUT THERE ONLY SEE THESE GUYS AND THEY DON'T SEE WHAT I SEE.

NARRATOR: MANY CORALS GLOW AND THEY USE THE FLUORESCENT LIGHT TO FEED ALGAE WITHIN THEIR CELLS.

OTHERS HAVE BRIGHT COLORS AROUND THEIR MOUTH AND TENTACLES, AND THEY USE THIS TO ATTRACT PREY.

PADDY: IT WAS JUST PHENOMENAL TO SEE HOW MANY ANIMALS EMIT A GLOW YOU CAN'T SEE WITH OUR RED VISION, AND THAT TO ME IS NUTS.

THE REEF IS EVEN NUTTIER THAN I THOUGHT IT WAS.

A LOT OF BOOKS SAY BEFORE WE UNDERSTAND THE GREAT BARRIER REEF PROPERLY, WE'LL COMPLETELY UNDERSTAND THE HUMAN BRAIN, WHICH IS A NICE WAY OF SAYING THERE'S JUST TOO MUCH OUT THERE TO EVER UNDERSTAND.

ON THE SURFACE HERE, WE'RE BROUGHT UP THINKING WE'RE SO IMPORTANT AND WE'RE NEXT STEP INTO BEING GOD, BUT DOWN THERE, YOU REALIZE HOW INSIGNIFICANT YOU FEEL.

NARRATOR: THIS AQUATIC UNIVERSE HAS GIVEN THE CREATURES OF THE REEF SOME SERIOUS ARTISTIC LICENSE.

YOU NEED GREAT IMAGINATION TO EVEN CONTEMPLATE THE STRANGE LIVES THEY LEAD.

[THUNDER] IN THE SKY, A DIFFERENT KIND OF LUMINOSITY.

THE DISTANT FIREWORKS OF LATE SUMMER ANNOUNCE A CHANGE IS ON THE WAY.

A TROPICAL STORM IS BREWING, FUELED BY THE VIOLENT CLASH OF WET MONSOONAL AIR AND THE WARM TROPICAL SEA.

BUT THIS IS NO ORDINARY STORM.

IT'S THE OMEN OF A CYCLONE OVER A THOUSAND MILES AWAY.

REPORTER: TONIGHT THE SOLOMON ISLANDS ARE FACING DEVASTATION AND DESPAIR AS THE WORST FLOODING IN HISTORY CLAIMS THE LIVES OF OVER TWENTY PEOPLE AND LEAVES THOUSANDS HOMELESS IN THE CAPITAL HONIARA AND VILLAGES ACROSS GUADALCANAL PROVINCE.

NARRATOR: THE STORM IS NOW BUILDING IN INTENSITY AND HEADING FOR THE AUSTRALIAN COAST.

THE ROUGH WEATHER HASN'T STOPPED THE HARDENED CREW FROM CAIRNS MARINE.

PROFESSIONAL AQUARIUM FISH COLLECTOR TIM BENNETT AND HIS SONS ARE OUT WORKING TO FILL THE HOLDS AND STORAGE DRUMS OF THEIR 72-FOOT VESSEL.

BUT WORSENING WEATHER IS MAKING IT FAR FROM EASY.

TIM: ACCORDING TO THE BUREAU OF METEOROLOGY, WE MIGHT HAVE A CYCLONE COMING OUR WAY.

IF THEY'RE ON THE MONEY, WE'LL BE PULLING IT UP SHORT, BASICALLY.

WE CAN'T WORK IN THOSE CONDITIONS.

NARRATOR: FOR NOW, THE DEEP STILL GIVES SHELTER FROM THE WIND AND RAIN ABOVE.

THE CREW HAVE JUST SPOTTED A CREATURE THEY'VE BEEN ASKED TO COLLECT FOR A PUBLIC AQUARIUM.

A 70-POUND THORNY RAY.

THE ONLY WAY TO CATCH IT UNHARMED IS BY HAND.

TIM: CATCHING THORNY RAYS, YOU'VE GOT TO BE ON YOUR GAME.

THEY DON'T HAVE A SPINE ON THEIR TAIL, BUT THEY ARE REALLY ROUGH.

WHEN YOU GRAB A BIG STINGRAY, YOU CAN'T LET GO OF IT.

IF YOU LET GO OF IT, YOU'LL GET REALLY HURT.

THEY CUT YOUR HANDS TO RIBBONS.

WITH BIG ANIMALS, YOU JUST HAVE TO COMMIT TO IT.

NARRATOR: A MILE AWAY, ON THE REEF EDGE, TIM'S SON CALE IS AFTER THE YELLOW AND PINK ANTHIAS THAT COLOR THE BOMMIES ALL AROUND HERE.

THEY ARE SOME OF THE MORE POPULAR FISH IN DOMESTIC AQUARIUMS AROUND THE WORLD.

USING A BARRIER NET, HE WORKS TO CORRAL THEM INTO HIS GRASP.

BUT, SUDDENLY, THERE'S A PROBLEM.

50 FEET ABOVE HIM, HIS BOAT HAS ROLLED AND HIS AIR SUPPLY HAS BEEN CUT OFF.

THE BOAT HAS DRAGGED ITS ANCHOR AND IS BEING SMASHED ONTO THE REEF.

HE HAS TO GET HIS BOAT AWAY FROM THE REEF BEFORE IT'S COMPLETELY DESTROYED.

THE BREAKING WAVES AND JAGGED REEF MAKE IT DIFFICULT.

HIS ONLY OPTION IS TO USE THE ANCHOR LINE TO TRY AND DRAG THE BOAT OUT BY HAND.

CALE: JUST LET THAT ONE OUT A BIT, DAD.

NARRATOR: THE BOAT CAN BE REPAIRED, BUT THE INCIDENT SENDS A CLEAR MESSAGE TO CAPTAIN TIM.

THE DETERIORATING CONDITIONS ARE MAKING THINGS TOO DANGEROUS TO CONTINUE.

TIM: COULD BE WORSE.

IT COULD HAVE BEEN THE MAIN BOAT, SO I'LL JUST HAVE TO HAVE A TEASPOON OF CEMENT AND GET OVER IT.

IT'S UPRIGHT NOW, AND IT'LL BE ALL RIGHT.

VERY REASSURING TO HAVE A CAPABLE CREW.

WHEN THINGS GET A BIT STICKY AND A BIT TRICKY, THEY'LL SAVE YOUR LIFE, RATHER THAN GET YOU KILLED.

MAYBE HAVE AN EXTRA BEER TONIGHT.

NARRATOR: AS THE CREW HEAD BACK TO PORT, THE BUREAU OF METEOROLOGY RELEASES SOME ALARMING NEWS.

THE BUILDING STORM, NOW OFFICIALLY NAMED CYCLONE ITA, IS SO POWERFUL, THEY'RE NOT THE ONLY ONES OUT HERE ON THE MOVE.

SEABIRDS HEAD NORTH TO AVOID THE STORM.

SHARKS, SENSING THE DROP IN BAROMETRIC PRESSURE, ALSO HEAD FOR DEEPER WATER.

LOBSTERS SCURRY TO FIND A BOLTHOLE.

CYCLONES, OR HURRICANES, AS THEY ARE KNOWN IN THE NORTHERN HEMISPHERE, FORM WHEN THE OCEAN'S SURFACE TEMPERATURE IS OVER 78 DEGREES FAHRENHEIT.

THE OCEAN WHERE CYCLONE ITA IS BUILDING IS OVER 82 DEGREES FAHRENHEIT.

THE ENERGY IN THE SYSTEM IS NOW EQUIVALENT TO A 10-MEGATON NUCLEAR BOMB EXPLODING EVERY 20 MINUTES.

REPORTER: FAR NORTH QUEENSLAND IS ON ALERT AS TROPICAL CYCLONE ITA CONTINUES TO GATHER STRENGTH IN THE CORAL SEA.

NARRATOR: FOR THE RESIDENTS OF COOKTOWN, IT'S TIME TO BRACE.

REPORTER: COOKTOWN IS THE BIGGEST COMMUNITY IN THE DANGER ZONE, AND LOCALS HAVE BEEN WARNED.

NARRATOR: IN 8 HOURS, CYCLONE ITA COULD MAKE A DIRECT HIT.

WOMAN: WHAT CAN I DO?

WHEN BIG HIT LIKE THIS, LIKE MONSTER THAT I'M SCARING VERY, VERY MUCH.

OSCAR: WE'RE EXPECTING A BIT OF A BREEZE.

A CATEGORY 5 BREEZE.

NARRATOR: CATEGORY 5 IS THE HIGHEST POSSIBLE CYCLONE RATING.

NOW IS THE CALM BEFORE THE STORM.

FOR GENERATIONS, SAILORS HERE HAVE SOUGHT REFUGE FROM CYCLONES IN THE MANGROVES.

THEIR NARROW CREEKS AND THICK FOLIAGE PROVIDE PROTECTION FROM WIND, WAVES, AND STORM SURGE.

FOR LOCAL RESIDENT OSCAR OB ERHAUSER, IT'S A LAST RESORT.

NO ANCHOR OR MOORING WILL SURVIVE THE FULL BRUNT OF THE CYCLONE.

OSCAR: I LIVE ON THE BOAT, I BUILT IT.

TAKE THIS AWAY AND I'M... THAT'S IT, SO IT'S ALL I'VE GOT.

MAN: LOOK OUT BEHIND YA, BEHIND YA!

OSCAR: BUT IT'S ALL RIGHT, WE'RE HERE.

NARRATOR: OSCAR CAN ONLY HOPE THE MANGROVES WILL SAVE HIS HOME, BUT HE'S NOT THE ONLY ONE PREPARING FOR THE WORST.

FURTHER INLAND, THE ANIMALS OF THE RAINFOREST ALSO SENSE THE APPROACHING STORM.

THE RAPID DROP IN AIR PRESSURE SIGNALS A CATASTROPHE IS LOOMING.

[THUNDER, RAIN FALLING] SATELLITES SHOW CYCLONE ITA IS AFFECTING AN AREA OF OVER 300 MILES ACROSS.

WIND GUSTS AT ITS CORE ARE CLOCKED AT 190 MILES PER HOUR.

PEOPLE IN COOKTOWN ARE PREPARING FOR THE WORST.

MAN: ONE MORE, BRIZ.

MAYOR: DON'T BE OUT IN THE WIND [INAUDIBLE].

TREAT ALL POWER LINES AS LIVE.

MAN: THAT'S A REALLY IMPORTANT MESSAGE.

MAYOR: IT'S AN OLD TOWN, COOKTOWN.

IT WAS ESTABLISHED IN THE GOLD RUSH DAYS, YOU KNOW, BACK IN THE 1880s, 1890s.

SO THERE IS CONCERN ABOUT, UM, SOME OF THE ICONIC OLD BUILDINGS AROUND TOWN.

WHAT'S COMING THROUGH NOW IS A HIGH TO INTENSITY CATEGORY 5.

IF WE GET A DIRECT HIT, THIS PLACE HAS NEVER HAD ANYTHING LIKE THAT.

THAT REALLY IS, UM, YOU KNOW, WE'RE IN UNCHARTERED WATERS.

NARRATOR: FOR MANY LOCALS, THE ONLY OPTION IS TO MOVE INTO THE REINFORCED TOWN CYCLONE SHELTER.

WOMAN: WE HAVEN'T HAD ONE SINCE 1949, AND IT'S A HUGE ONE.

[GUSTING WINDS, RAIN] NARRATOR: WINDS ARE NOW GUSTING AT OVER 75 MILES PER HOUR.

AND THERE'S ONLY ONE RESTAURANT WILLING TO OPEN ITS DOORS.

JOHN: WE ALWAYS COOK UP A STORM.

THE LAST SUPPER RIGHT AT THE WOGS.

HAS TO BE THE ONLY PLACE IN COOKTOWN.

WHEN MOTHER NATURE'S A BIT ANGRY, WE JUST GOT TO MAKE SURE NO ONE GETS HURT AND JUST HELP EACH OTHER OUT AND IF ANYONE'S IN STRIFE, JUST GIVE 'EM A ROOF THAT'S NOT GONNA BLOW OFF, I SUPPOSE.

THE STEAK BEFORE THE STORM.

NOW, COME ON, YOU GOT A BIGGER MOUTH THAN THAT, GARY!

GARY: THANKS JOHN.

JOHN: AT THE WOGS.

GOOD LUCK, COOKTOWN.

KEEP SAFE.

[GLASS BREAKING] NARRATOR: AT 9:00 PM, CYCLONE ITA MAKES LANDFALL.

THE WIND TEARS THROUGH TOWN.

[WIND, RAIN, DOG BARKING] THE MORNING AFTER, AND THE RESIDENTS EMERGE TO SEE HOW MUCH OF THE TOWN IS LEFT STANDING.

FORTUNATELY, CYCLONE ITA HAD LOST SOME OF HER FURY BY THE TIME SHE REACHED COOKTOWN.

IT'S NOT AS DEVASTATING AS IT COULD HAVE BEEN.

BUT THERE'S STILL A TRAIL OF DESTRUCTION.

JOHN: UNBELIEVABLE.

USED TO BE A BEAUTIFUL TREE, THIS.

I LOVE ME TREES.

[ DOG WHIMPERING ] YOU OKAY?

POOR BUGGER.

WOMAN: THE WIND WAS HOWLIN' AND THE TREES WERE CRACKIN' AND IT WAS JUST WHOOSH OVER THE TOP OF US ALL THE TIME.

THEN THE IRON FROM THE BIG PUB ACROSS THE ROAD WAS BANGIN' ACROSS THE FENCES, AND, YEAH, IT WAS REALLY SCARY.

NARRATOR: THE WEST COAST PUB STANDS IN SPLINTERS.

THE ROOF PEELED OFF LIKE A TIN CAN.

JOHN: WHAT HAPPENED?

YOU DOIN' RENOVATIONS?

DAVE: YEAH, MATE, WE THOUGHT WE'D GET IT READY FOR EASTER.

JOHN: AT LEAST THE WEATHER WOULD BE BETTER.

WHAT A MESS, EH?

DAVE: YEAH, MATE, BUT AT LEAST WE GOT HER OFF IN ONE PIECE.

JOHN: YEAH.

NAH.

NARRATOR: PUBLICAN DAVE SHELTERED IN THE BEER FRIDGE DURING THE STORM.

ANY QUEENSLANDER WILL TELL YOU IT'S A VERY SAFE PLACE.

DAVE: WELL, THIS IS WHERE WE WERE.

THIS IS WHERE WE ENDED UP.

UM, WE MADE A DECISION NOT TO STAY IN THE HOTEL LAST NIGHT AND UM, SO WE DRAGGED A COUPLE OF MATTRESSES OVER.

WE STACKED ALL THE SOUTHERN BEER OVER THERE AND WE HAD THE TYPICAL QUEENSLAND BEDSIDE TABLE.

HAD TO BE GOLD.

JOHN: YEAH, GOOD ON YOUSE, MATE.

DAVE: AND WHEN IT GOT A BIT WILD, WE SHUT THE DOOR AND, UH, LET THE WORLD GO BY.

JOHN: I'M PROUD OF YA, MATE.

YOU DONE IT RIGHT.

DAVE: THEY'RE A GOOD MOB OF PEOPLE IN THIS TOWN AND, UH, THEY NEED OLD PLACES LIKE THIS.

IT MIGHT BE A BIT OF AN OLD RAMSHACKLE, BUT THESE PLACES HAVE GOT HERITAGE AND THEY... JOHN: YES, TRUE.

DAVE: THEY NEED THIS SORT OF THING.

IT'S PART OF 'EM.

THIS MAN'S GOT THE ITALIAN RESTAURANT ACROSS THE ROAD AND, IN SOME WAYS, WE'RE COMPETITORS, BUT, UM, HE'S THE FIRST MAN OVER HERE, SO, YEAH.

NO, IT'S GOOD, YEAH.

JOHN: THAT'S THE WAY IT SHOULD BE IN A TOWN LIKE THIS.

DAVE: YEAH, MATE, YEAH.

JOHN: EH, WHICH IS GOOD.

DAVE: YEAH.

NARRATOR: IN THE HARBOR, OSCAR'S MAKING THE NERVOUS JOURNEY TO SEE IF THE MANGROVES HAVE KEPT HIS BOAT SAFE THROUGH THE NIGHT.

OSCAR: THAT'S A SAD SIGHT, ISN'T IT?

AH, EH, ALL RIGHT, EH?

YEAH, THIS IS STUFFED.

BUT NOT BAD, NOT BAD.

THESE ARE MARVELOUS THINGS, THESE MANGROVES, AREN'T THEY?

YOU CANNOT BELIEVE JUST HOW EFFECTIVE THEY ARE AGAINST STRONG WIND.

ASTONISHING.

NARRATOR: HIS BOAT IS BATTERED BUT STILL AFLOAT.

THE MANGROVES HAVE CRADLED HER THROUGH THE STORM AND PREVENTED LARGE AREAS OF COASTLINE FROM SEVERE EROSION.

OSCAR WAS LUCKY.

BUT THE REEF OUT NEAR LIZARD ISLAND BORE THE FULL BRUNT OF THE STORM, RECORDING WIND SPEEDS AROUND 130 MILES AN HOUR.

A TEAM FROM THE CATLIN SEAVIEW PROJECT HAVE COME TO SURVEY THE DAMAGE.

USING A 360-DEGREE CAMERA, THEY'VE BEEN GATHERING BASELINE INFORMATION ON THE HEALTH OF THE GREAT BARRIER REEF.

IT JUST SO HAPPENS, THEY SURVEYED THIS EXACT AREA ABOUT A YEAR AGO.

THIS IS HOW IT LOOKED BEFORE THE STORM.

A GIANT CLAM LIVING IN DENSE CORAL.

AND HERE IT IS TODAY.

THE DEVASTATION ON THE MOST EX POSED REEFS IS GUT-WRENCHING.

BOMMIES HAVE BEEN ROLLED OVER THE BOTTOM LIKE WRECKING BALLS.

BRANCHING CORALS REDUCED TO PILES OF RUBBLE.

OVER THE LAST DECADE, DESTRUCTIVE STORMS HAVE ACCOUNTED FOR ABOUT 48% OF THE DECLINE IN CORAL COVER.

CLIMATE SCIENTISTS FORECAST THAT WITH RISING GLOBAL TEMPERATURES, THE INTENSITY OF STORMS WILL CONTINUE TO INCREASE.

IN 24 HOURS, CYCLONE ITA HAS DUMPED 16 INCHES OF RAIN ACROSS FAR NORTH QUEENSLAND.

WATERFALLS NOW THUNDER THROUGH THE RAINFOREST.

AS RIVERS SPILL OUT ONTO THE INNER REEF, PLUMES OF SEDIMENT CLOUD THE WATER.

JUST OFF CARDWELL, COMMERCIAL FISHERMAN GLEN MURRAY AND HIS SON BEN ARE ON THE HUNT FOR THREADFIN SALMON.

BUT THE SILT PLUME FROM THE CYCLONE IS MAKING IT A LEAN DAY ON THE WATER.

GLEN: NOT REAL GOOD SO FAR, BUT ANYWAY WE'LL KEEP ON TRYING.

THAT'S FISHING.

IF YOU CAUGHT THEM ALL THE TIME, IT'D BE CALLED CATCHING.

NARRATOR: GLEN AND BEN ARE CONNECTED DEEPLY TO THE HEALTH OF THE REEF.

IF THEY DON'T CATCH, THEY DON'T EAT.

GLEN: HAS TO BE 40, SO HE'S GOOD.

HE'S PROBABLY ABOUT $4 WORTH, SO YEAH, SO WHAT WE NEED IS ANOTHER COUPLE OF THOSE AND WE'VE PAID FOR THE FUEL SO FAR TODAY, SO... BEN: OH, WELL.

GLEN: OH, DON'T WORRY, MATE, YOU GET, UH, A 5th OF THE CATCH, 20%.

SO YOU MIGHT HAVE MADE $1 OUT OF THAT TODAY.

YEAH, DID ALL RIGHT.

GOOD DAY, GOOD DAY.

OH, WELL, MAYBE WE'LL GET BETTER LUCK WITH THE CRAB.

JUST GRAB THAT ONE, BEN, SEE WHAT WE'VE GOT.

TAKE THE GOOD WITH THE BAD.

WHEN THE CRABS ARE TOGETHER, THEY, UH, DO FIGHT.

JUST GET HER OUT OF THERE.

SHE'S THROWN HER NIPPER OFF THERE AS A DEFENSE MECHANISM.

AND THAT ALLOWS THEM TO SWIM AWAY OR RUN AWAY, AND WHATEVER THEY'VE LOCKED ONTO THEN HAS TO FIGHT TO TRY AND GET THAT NIPPER OFF.

YOU CANNOT ACTUALLY PRIZE THAT APART.

DON'T GET IT ON YOUR FINGER.

VERY, VERY, VERY PAINFUL.

NARRATOR: GLEN IS ONE OF AROUND 1,500 LICENSED COMMERCIAL FISHERMEN OPERATING IN THE WATERS OF THE GREAT BARRIER REEF.

GRASSROOTS INDUSTRIES THAT ARE IMPORTANT TO MANY LOCAL COMMUNITIES UP AND DOWN THE COAST.

GLEN: WE'RE HERE FOR THE LONG HAUL.

MY SON, HE'S ONLY 20 YEARS OF AGE, SO, HOPEFULLY, HE'LL BE STILL ABLE TO COME OUT AND DO THIS COMMERCIAL FISHING WHEN HE'S 50 LIKE I AM.

WE'VE GOT TO LOOK AFTER THE ENVIRONMENT ITSELF THERE, BECAUSE THE FISH RELY ON IT, AND SO DO WE.

NARRATOR: FOUR AND A HALF THOUSAND SHIPS TRANSIT THROUGH HERE EVERY YEAR, TRANSPORTING COAL FROM AUSTRALIA'S MINES TO THE REST OF THE WORLD.

AND WITH THE RESOURCE BOOM SHOWING NO SIGNS OF SLOWING, SHIP NUMBERS ARE SET TO DOUBLE OVER THE NEXT 20 YEARS.

FROM A CONTROL ROOM IN TO WNSVILLE, SHIPS ARE MONITORED AS THEY ENTER THE REEF.

RADIO: REEF VTS, DO YOU COPY?

WE'RE COMING DOWN THE WEST CHANNEL, OVER.

OPERATOR: COPY REEF VTS ROMEO, SIR.

WE HAVE SOUTHBOUND VESSEL, THE DOM VIEN GIANT, NUMBER TWO IN THE VICINITY OF HOLBOURNE ISLAND.

REEF VTS STANDING BY CHANNEL 1-1.

IT'S LIKE AIR TRAFFIC CONTROL FOR SHIPS.

MICK: AT ANY ONE TIME, THERE'S PROBABLY ABOUT 40 OR 50 SHIPS MOVING THROUGH THE REEF.

THE BIG ISSUE HERE, THOUGH, IS THAT THE NAVIGATION'S VERY COMPLEX.

SHIPS ARE DIFFICULT TO MANEUVER.

UNLIKE CARS, VESSELS DON'T HAVE BRAKES.

ONCE IT'S GOT A MOMENTUM, IT CAN TAKE MILES FOR A VESSEL TO STOP.

NARRATOR: THE CONTROLLER'S PRIMARY ROLE IS TO PREVENT AN ENVIRONMENTAL DISASTER.

OPERATOR: WE'VE GOT A COUPLE OF DESIGNATED AREAS WHERE WE'VE GOT CRITICAL TURNS, FAIRLY TIGHT CORRIDORS WHICH THE SHIP NEEDS TO NAVIGATE THROUGH.

THIS VESSEL HERE HAS, UH, CONDUCTED A CRITICAL TURN EARLIER ON.

YOU CAN SEE THAT DOTTED LINE, THAT'S WHERE THE ACTUAL SHIP CONDUCTED ITS TRANSIT 'ROUND THE TURN.

IF THEY GO WITHIN THE BOUNDARIES OF THOSE CORRIDORS, IT TRIGGERS AN ALARM FOR US AND WE HAVE ENOUGH TIME GENERALLY TO TAKE ACTION TO AVOID GROUNDING.

[INAUDIBLE RADIO CHATTER].

NARRATOR: ALL SHIPS OVER 70 METERS REQUIRE LOCAL CAPTAINS, CALLED REEF PILOTS.

THEY BOARD THE VESSELS AS THEY ENTER THE REEF AND HELP TO TRANSIT THEM SAFELY THROUGH THE MARINE PARK.

[INAUDIBLE RADIO CHATTER].

[INAUDIBLE RADIO CHATTER].

MICK: PILOTS ARE LOCAL OPERATORS ALL TRAINED IN THESE AREAS, SO THEY'RE VERY EXPERIENCED WITH THE WATERS.

WHILE THE SHIP HAS GOT ITS OWN SAFETY MECHANISMS, THE ADDITION OF A PILOT WHO KNOWS THE WATERS VERY, VERY WELL IS EXTREMELY IMPORTANT.

NARRATOR: DESPITE ALL THESE MEASURES, A BREAKDOWN, A COLLISION, OR HUMAN ERROR CAN NEVER BE ENTIRELY RULED OUT.

REPORTER: TONIGHT A POTENTIAL ENVIRONMENTAL DISASTER APPEARS TO BE UNFOLDING ON THE GREAT BARRIER REEF.

NARRATOR: IN APRIL 2010, THE CHINESE BULK CARRIER "SHEN NENG" STRAYED FROM ITS COURSE AND RAN FULL SPEED INTO A SHALLOW REEF KNOWN AS THE DOUGLAS SHOALS.

THE SHIP WAS OUTSIDE THE MONITORING ZONE AND WAS 18 MILES OFF ITS DESIGNATED COURSE.

MAN: THE TOP OF THE SHOAL HAS BEEN COMPLETELY PULVERIZED.

ANNA: WHAT WE'RE WORRIED ABOUT IS MAKING SURE WE KEEP THAT OIL CONTAINED IN THE SHIP AND OFF THE WATERS OF THE BARRIER REEF AND THE BEACHES SURROUNDING IT.

REPORTER: MORE SCIENTISTS ARE ON THE WAY TO ASSESS THE SHIP'S TRAIL OF DESTRUCTION.

ANNA: THIS IS THE GREAT BARRIER REEF MARINE PARK AND ANY OIL IS UNACCEPTABLE.

NARRATOR: FORTUNATELY, THE VESSEL'S HULL REMAINED LARGELY INTACT AND THE SPILL WAS RELATIVELY MINOR.

SINCE THE ACCIDENT, THE VESSEL MONITORING AREA HAS BEEN INCREASED, AS HAVE THE SECTIONS OF THE REEF WHERE PILOTS ARE REQUIRED.

BUT THE RISK TO THE REEF WILL ONLY INTENSIFY WITH INCREASING TRAFFIC.

THE DIFFICULT BALANCING ACT OF COMMERCE AND CONSERVATION PLAYS OUT ACROSS FIFTEEN HUNDRED MILES OF COASTLINE.

FISHING IS AN IMPORTANT INDUSTRY ON THE REEF.

BUT RULES ARE IN PLACE TO ENSURE THE FISHING IS DONE SUSTAINABLY.

[INAUDIBLE RADIO CHATTER] NARRATOR: 6:00 A.M., SOMEWHERE ON CAPE YORK.

THE AUTHORITIES HAVE RECEIVED INTEL THERE'S SOMEONE OPERATING ILLEGALLY NEARBY.

MAN: ONE OF OUR TARGETS WASN'T WHERE HE WAS SUPPOSED TO BE.

THE PLAN IS WE'RE GONNA TAKE THE VESSEL DOWN.

LET'S GO.

NARRATOR: THESE TEAMS ARE RESPONSIBLE FOR POLICING THE RIVERS, OCEANS, BEACHES, AND ISLANDS OF THE ENTIRE REEF.

AND WITH AN AREA THE SIZE OF ITALY, IT'S NO EASY TASK.

PILOT: A HELICOPTER RUN LIKE THIS, WE WOULD DO ANYWHERE BETWEEN 7, 8 HOURS A DAY AND AVERAGING AROUND 160 K's AN HOUR.

YOU CAN IMAGINE HOW FAR THAT IS.

IT WOULD BE 500, 800 K's.

IT COULD BE 1,000 K's A DAY, AT TIMES.

[INAUDIBLE RADIO CHATTER].

SOME OF THE FISHERIES IN THIS AREA, UH, YOU'VE GOT COMMERCIAL NETTING, COMMERCIAL CRABBING.

OFFSHORE, YOU'VE GOT MACKEREL FISHING, LINE FISHING, CRAY FISHING.

THERE'S TRAWLERS, CORAL COLLECTORS, FISH COLLECTORS.

SO THERE'S ALL THOSE FISHERIES OPERATING INSHORE AND ALSO OFFSHORE IN THIS AREA.

WE OFTEN USE A BIT OF STEALTH, UM, KNOWING THAT THERE'S A TARGET OF INTEREST IN THE AREA, AND WELL, WE CAN USE THE WIND, WE CAN HAVE THE SUN, UM, DIFFERENT ANGLES, COME DOWN FROM HIGH UP IN THE SKY.

IT'S QUITE EASY TO SURPRISE PEOPLE.

RADIO: LOOKS LIKE HE'S OKAY, MATE, HE'S OUTSIDE THE GREEN ZONE.

NARRATOR: THE ENTIRE MARINE PARK IS DIVIDED INTO A PATCHWORK OF CONSERVATION ZONES RANGING FROM PLACES WHERE ANYONE CAN FISH THROUGH TO STRICT NO-TAKE AREAS, OR GREEN ZONES.

THE CHOPPER CREW HAS JUST SPOTTED A VESSEL FISHING IN A RESTRICTED AREA.

PILOT: HEY, MATE, I'M QUITE SURE THAT WE'VE A BOAT IN THE GREEN UP THERE.

YEAH, ACCORDING TO MY iPAD.

SEE THAT TARGET OVER THERE?

PILOT 2: YEAH, GOT HIM NOW.

PILOT: THERE'S A VERY GOOD CHANCE HE'D BE IN A GREEN ZONE.

PILOT 2: YEP, NO WORRIES.

NARRATOR: THE BOAT'S DETAILS ARE RECORDED AND A HEFTY FINE WILL SOON FOLLOW.

PILOT: CAN SEE PEOPLE WITH, UH, HAND LINES, FISHING LINES IN THE WATER.

YEAH, IT MOST DEFINITELY APPEARS THAT THEY'RE FISHING, UH, WITHIN A GREEN ZONE, WHICH IS AN OFFENSE.

NARRATOR: LAST YEAR, A COMMERCIAL FISHERMAN WAS FINED $50,000 FOR OFFENSES.

BUT AS THE EVIDENCE TAPES SHOW, THAT DETERRENT IS SOMETIMES NOT ENOUGH.

PILOT: YOU CAN SEE THEM THROWING THINGS OVER THE SIDE, SCURRYING AROUND, QUICKLY TAKING THE COWLING OFF THE MOTOR, MAKING OUT THEY'VE BROKEN DOWN.

SOMETIMES THEY TRY TO HIDE THEIR FACES, PUT A BUCKET OVER THE HEAD.

THERE'S A WHOLE RANGE OF DIFFERENT BEHAVIORS THAT YOU SEE, AND IT IS QUITE FUNNY.

ALL RIGHT, HE JUST THREW A FISH OVERBOARD.

I'M JUST TRYING TO GET THE REGO.

NARRATOR: THE AUTHORITIES MAKE UP TO 50 PROSECUTIONS A YEAR AND ISSUE OVER 180 WARNINGS.

PILOT: THOSE TAKING FISH FROM THE GREEN ZONES ARE TAKING OUR FISH.

IT'S A COMMUNAL ASSET.

IT'S ABOUT PROTECTING DUGONG, LOOKING AT TURTLE, EVEN LOOKING AT CROCODILE.

IT'S ABOUT PROTECTING THE GREAT BARRIER REEF.

WE ALWAYS SAY THAT, UM, IT'S NOT IF BUT WHEN.

WE'VE GOT TIME AND WE'VE GOT DEDICATION AND WE ALWAYS GET THEM IN THE END.

NARRATOR: RAINE ISLAND, ON THE OUTER EDGE OF THE REEF, IS A PLACE SO PROTECTED, ONLY A FEW SCIENTISTS HAVE PERMISSION TO LAND HERE EACH YEAR.

AS THE WORLD'S LARGEST AND MOST IMPORTANT BREEDING GROUND FOR GREEN SEA TURTLES, ITS CONSERVATION IS CRITICAL.

ANDY: MORNING.

NARRATOR: IN RECENT YEARS, RISING SEA LEVELS HAVE BEEN CAUSING HIGH TIDES TO FLOOD TURTLE NESTS, WITH CATASTROPHIC RESULTS.

RESEARCHER ANDY DUNSTAN IS HERE TO SEE WHAT CAN BE DONE TO PROTECT THE ROOKERY.

ANDY: THIS IS MEASURING, UH, THE HEIGHT OF THE WATER TABLE.

AS THE TIDE COMES UP, THE WATER SEEPS THROUGH THE SAND.

IF IT INUNDATES THE NESTS FOR PROBABLY MORE THAN 30 MINUTES FOR OVER A THREE-DAY PERIOD, THEN THE EGGS ARE GONNA DIE.

WE SHOULD SEE, EACH NIGHT, 400,000 HATCHLINGS MAKING THE WATER.

FROM WHAT WE'VE SEEN IN THE LAST FEW YEARS, THAT WOULD BE HIGHLY UNLIKELY.

NARRATOR: ANDY IS WORKING WITH MARINE PARK SCIENTIST MARK READ TO UNDERSTAND HOW SERIOUS THE PROBLEM IS.

MARK: ONE OF THE THINGS THAT DRAWS PEOPLE TO STUDYING SEA TURTLES IS JUST HOW DIFFICULT IT IS FOR THEM, AS A SPECIES, TO MAKE THEIR WAY IN THE WORLD.

YOU KNOW, THEY'VE BEEN AROUND FOR A COUPLE OF HUNDRED MILLION YEARS, BUT AT EVERY STAGE IN THEIR LIVES, IT'S A HARD-WON BATTLE.

AND THAT REALLY HIGHLIGHTS JUST WHY IT'S SO IMPORTANT TO UNDERSTAND HOW RAINE ISLAND IS FUNCTIONING AS A ROOKERY, AND IF IT'S NOT FUNCTIONING PROPERLY, WHAT WE CAN DO TO MAKE A DIFFERENCE.

NARRATOR: BY DIGGING A TRENCH AL ONG THE SHORELINE, HATCHLINGS WILL BE CAUGHT AND COUNTED AS THEY LEAVE THE BEACH.

IT'LL BE A LONG AFTERNOON AND AN EVEN LONGER NIGHT AHEAD.

IT'S APRIL AND NEARING THE END OF THE HATCHING SEASON.

TWO HOURS AFTER THE SUN SETS, THE COOLING SAND TRIGGERS THE EMERGENCE OF THOUSANDS OF HATCHLINGS.

THEY BEGIN THEIR FRANTIC RACE TO THE WATER'S EDGE.

BUT THE TRENCH ISN'T THE ONLY OBSTACLE THEY'LL FACE TONIGHT.

GHOST CRABS ALSO HAUNT THE BEACH.

THE LUCKY ESCAPEES MAKE A FINAL PUSH.

ANDY: FIVE.

WOW, THIS IS, UM, TURNING OUT TO BE QUITE A BIG HATCHLING NIGHT.

WELL, WE'RE COUNTING A 50- METER SECTOR OF WHERE WE DID OUR NESTING-SUCCESS COUNTS EARLIER IN THE YEAR.

MARK: THAT'S 55 IN MY LITTLE BAG FULL OF TURTLES.

I'M GONNA TAKE THESE DOWN AND LET THEM GO AT THE OTHER END OF THE TRENCH, BACK INTO THE WATER.

IN MANY WAYS, THE LITTLE HATCHLINGS ARE JUST LIKE LITTLE WIND-UP TOYS.

YOU LET THEM GO, AND THEY KEEP ON SCURRYING.

IT'S AN AMAZING BURST OF ENERGY, THE FIRST SORT OF 24 HOURS OF JUST GOING FOR IT, TRYING TO GET AWAY FROM THIS ISLAND.

IT REALLY ENHANCES THEIR CHANCES OF SURVIVAL.

ANDY: THAT'S ANOTHER 122 HATCHLINGS IN THE LAST FIVE MINUTES.

SO, IT DOES LOOK LIKE A LOT, BUT THAT'S ONLY ONE NEST.

NARRATOR: ON THE BEACH HERE, THE BABIES FACE PREDATION BY CRABS AND BIRDS, AND ONCE THEY MAKE THE WATER, THERE ARE THOUSANDS OF OTHER PREDATORS THAT AWAIT THEM.

THE KEY TO SURVIVAL IS GETTING AWAY FROM THE REEF UNDER COVER OF DARKNESS AND OUT INTO THE DEEP OCEAN.

COME DAWN, HATCHING HAS STOPPED.

PREDATORS MAKE THE DAYTIME JOURNEY TOO RISKY.

WHILE IT APPEARED TO BE A BUSY NIGHT, THE NUMBERS WERE WELL BELOW EXPECTED.

MARK NOW HAS THE GRUESOME JOB OF COUNTING THE TURTLES THAT DIDN'T MAKE IT.

MARK: WHAT I'M TRYING TO DO HERE IS I'M TRYING TO GET A MEASURE OF HOW MANY HATCHLINGS HAVE ACTUALLY SUCCESSFULLY EMERGED FROM THE EGGS.

AND OF THOSE EGGS THAT REMAIN OUT OF THIS CLUTCH, I'M THEN OPENING THEM UP TO SEE WHETHER OR NOT WE'VE GOT SOME THAT HAVE ALMOST FULLY DEVELOPED BEFORE THEY DIED.

AND THEN WE'VE GOT THESE OVER HERE THAT HAVE BARELY STARTED DEVELOPING BEFORE THEY'VE THEN STOPPED.

NARRATOR: ONLY 5% OF EGGS ARE CU RRENTLY PRODUCING HATCHLINGS, AND OF THOSE, IT'S ESTIMATED THAT ONLY 1 IN 1,000 WILL SURVIVE TO ADULTHOOD.

MARK: ALL OF THE DATA INDICATES THAT THIS PLACE ISN'T FUNCTIONING PARTICULARLY WELL AS A TURTLE ROOKERY, AND THAT'S A REALLY BLEAK PICTURE FOR THE WORLD'S LARGEST AGGREGATION OF NESTING GREEN TURTLES.

NARRATOR: WITH RISING SEA LEVELS FLOODING THE NESTS, MARK AND ANDY BELIEVE THAT THE ONLY WAY TO HELP SECURE THE ROOKERY IS TO RAISE THE HEIGHT OF THE SAND.

IF THE NESTING AREA IS MADE HIGH AND DRY, IT COULD TURN THE TIDE FOR THIS ENDANGERED SPECIES.

MARK: ALL OF IT IS ABOUT IMPROVING THE CHANCES FOR SUCCESS.

RATHER THAN LEAVING THIS LITTLE GUY ON THE BEACH IN THE HEAT OF THE DAY AND ALSO EXPOSED TO THE PREDATORS, WE'LL JUST TAKE HIM DOWN AND GIVE HIM AT LEAST A FIGHTING CHANCE OF SWIMMING OUT THERE INTO THE OCEAN AND BECOMING PART OF THE NEXT GENERATION.

THE CHANCES OF IT ACTUALLY BECOMING AN ADULT ARE VERY, VERY SLIM, INDEED.

BUT PART OF THE WHOLE STORY OF THE REEF AND PRETTY MUCH WHAT EVERYBODY IS DOING IS JUST TO IMPROVE THE FIGHTING CHANCE OF THE WHOLE ECOSYSTEM.

SO WHILST IT MIGHT SEEM A TRIVIAL THING FOR US TO TAKE ONE INDIVIDUAL HATCHLING DOWN AND LET IT GO, UM, JUST TO IMPROVE ITS CHANCES, EVERY LITTLE BIT COUNTS.

HE'S JUST GOING ACROSS THE REEF FLAT NOW, SO HE'S RUNNING THE FIRST GAUNTLET OF MANY.

NARRATOR: THE HATCHLINGS NOW LEAVE RAINE ISLAND TO DRIFT ON PACIFIC OCEAN CURRENTS.

IT'LL BE ABOUT 10 YEARS BEFORE THEY SEE LAND AGAIN AND AROUND 30 YEARS BEFORE THEY COME BACK TO RAINE ISLAND TO NEST.

WHAT THEY FIND WHEN THEY RETURN WILL DEPEND ON WHAT HUMANS HAVE CHOSEN TO VALUE AND PROTECT.

JOHN: ALL RIGHT, HERE WE GO.

BEGINNING OF ANOTHER YEAR.

NARRATOR: THE YEAR HAS COME FULL CIRCLE.

WINTER IS BACK, AND DIVE OPERATOR JOHN ROMNEY IS HEADING OUT FOR AN EXTRAORDINARY TRIP.

JOHN: WE LIVE FOR THIS.

I NEVER GET TIRED OF GOING OUT TO SEE THIS WHOLE SENSE OF FREEDOM AND ADVENTURE AND YOU JUST DON'T KNOW WHAT'S GOING TO HAPPEN NEXT.

NARRATOR: EVERY JULY FOR THE LAST 20 YEARS, HE HAS FERRIED TOURISTS AND SCIENTISTS OUT TO THE RIBBON REEFS IN SEARCH OF DEEP-SEA GIANTS.

WOMAN: ONE, TWO, THREE!

JOHN: WE DON'T SEE THEM EVERY DAY.

WE END UP HAVING THEM EVERY TRIP.

SO YOU DEFINITELY HAVE TO LOOK.

WE HAVE ALL THE GUESTS STATIONED AROUND THE BOAT.

[ WHALE SINGING ] NARRATOR: THIS STRANGE SOUND SIGNALS AN APPROACH.

OUT OF THE BLUE, THE LEVIATHAN APPEARS.

ONLY DISCOVERED HERE A LITTLE OVER 30 YEARS AGO, THESE DWARF MINKE WHALES HA VE TRAVELLED OVER 4,000 MILES FROM THE SOUTHERN OCEAN TO BE HERE.

THE SMALLEST OF THE BALEEN OR TOOTHLESS WHALES, THESE DWARF MINKE'S STILL TOWER NEXT TO THE FLOATING TOURISTS.

JOHN: AMAZING THING ABOUT HERE ON THE BARRIER REEF WITH THESE DWARF MINKE WHALES IS THAT THEY SEEK US OUT.

THEY COME TO US.

BUT IT'S JUST THIS PRIVILEGE OF SHARING A MOMENT AND THEY'RE RECOGNIZING YOU, YOU'RE RECOGNIZING THEM AND BEING EYE-TO-EYE WITH A 7- METER ANIMAL THAT WANTS TO VISIT YOU IS JUST, UM, UNBELIEVABLE.

NARRATOR: JOHN WAS ONE OF THE FIRST TOUR OPERATORS TO ACTIVELY SUPPORT SCIENCE BY BRINGING RESEARCH AND TOURISM TOGETHER.

THE TRIPS ARE FUNDED BY TOURISTS, AND THE DATA BEING COLLECTED ON BOARD IS GIVING US A WINDOW INTO THEIR WORLD.

IT TURNS OUT THAT MOST OF THE WHALES THAT VISIT THE TOURISTS ARE TEENAGERS, POSSIBLY DOING SOMETHING A LITTLE NAUGHTY.

THE ADULTS APPEAR TO BE MORE CAUTIOUS, ONLY RARELY VISITING THE TOURIST VESSELS.

HERE, THEY'RE PROTECTED BUT OUTSIDE OF THE WARM, SAFE WATERS OF THE GREAT BARRIER REEF, THEY CAN BE TARGETED BY WHALERS IN THE ANTARCTIC.

JOHN: THIS IS JUST THE BIGGEST FRIENDLY ANIMAL IN THE WORLD.

EVERYONE THAT COMES, THEY LEAVE AS REEF AND WHALE AMBASSADORS, AND WE NEED MORE PEOPLE TO CARE IN ORDER TO PROTECT WHAT WE LOVE.

NARRATOR: THE MINKES' PRESENCE IS A REMINDER OF THE TRUE VALUE OF THE GREAT BARRIER REEF.

ITS FUNCTION EXTENDS FAR BEYOND THESE WATERS.

ITS WORTH IS ONE FOR ALL THE OCEAN.

THE GREAT BARRIER REEF MARINE PARK IS A WILD SPACE OF GLOBAL IMPORTANCE, WHERE VAST RIVERS MEET OCEAN CURRENTS... ...WHERE ANIMALS, PLANTS AND PEOPLE LINK THE LAND AND SEA TOGETHER.

GIVEN ITS SCALE, IT'S EASY TO THINK THE GREAT BARRIER REEF IS INDEPENDENT OF THE FORCES THAT SURROUND IT.

BUT IN NATURE, NOTHING EXISTS ON ITS OWN.

♪ ♪ ♪ ♪ "LIFE ON THE REEF" IS AVAILABLE ON BLU-RAY AND DVD.

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