0:00:44 > 0:00:49The South Pacific is a vast ocean wilderness.
0:00:52 > 0:00:54Its waters are teeming with life...
0:00:56 > 0:00:59..from tropical coral reefs that attract the great variety...
0:01:04 > 0:01:08..to the cooler, temperate waters that attract the great numbers.
0:01:26 > 0:01:30So why is it that in the midst of all this richness
0:01:30 > 0:01:33the world's largest predators can struggle
0:01:33 > 0:01:37to survive in this...endless blue?
0:01:53 > 0:01:56Nothing brings home the challenges of surviving
0:01:56 > 0:01:57in the South Pacific better
0:01:57 > 0:02:01than the epic true story that inspired Moby Dick.
0:02:09 > 0:02:14On 23rd February 1821, a lifeboat was found drifting
0:02:14 > 0:02:16in the eastern Pacific.
0:02:16 > 0:02:18CREAKING
0:02:18 > 0:02:21In it lay two American whalemen,
0:02:21 > 0:02:23barely alive.
0:02:23 > 0:02:25FEEBLE COUGHING
0:02:28 > 0:02:31Their whale ship had been sunk by an enormous sperm whale.
0:02:31 > 0:02:35For a staggering three months, these shipwrecked mariners had sailed
0:02:35 > 0:02:41across 4,500 miles of what may be the loneliest region on Earth.
0:02:42 > 0:02:47For these sailors, the South Pacific had become a living hell.
0:02:49 > 0:02:54So what is it about this ocean that makes survival here such a challenge?
0:02:59 > 0:03:02Of all the oceans, the Pacific is by far the largest,
0:03:02 > 0:03:06stretching almost a third of the way round the globe.
0:03:08 > 0:03:11It's so huge that the current in the South Pacific
0:03:11 > 0:03:14takes several years to complete just one cycle.
0:03:15 > 0:03:17SONAR-TYPE PINGING
0:03:17 > 0:03:20FAST CLICKING
0:03:22 > 0:03:24In an ocean this vast,
0:03:24 > 0:03:28many animals have to travel huge distances to survive.
0:03:32 > 0:03:35None more so than the sperm whale,
0:03:35 > 0:03:38one of the greatest voyagers on the planet.
0:03:41 > 0:03:44Every year, thousands of bull sperm whales,
0:03:44 > 0:03:49some from as far as Antarctica, come to the tropics to breed.
0:03:54 > 0:03:57CLICKING
0:03:57 > 0:04:02After 15 years away, fattening themselves up in colder climes,
0:04:02 > 0:04:07they are now back and big enough to compete for a mate.
0:04:08 > 0:04:13These warm, equatorial waters make ideal nurseries.
0:04:17 > 0:04:22At just a week old, this white calf already weighs over a tonne.
0:04:24 > 0:04:27For the next six years he will stay by his mother's side,
0:04:27 > 0:04:30relaxing in these tropical waters where killer whales,
0:04:30 > 0:04:34his only natural predator, are rarely found.
0:04:36 > 0:04:39But it was in these peaceful stretches of ocean
0:04:39 > 0:04:41that, 200 years ago,
0:04:41 > 0:04:44whales met whalemen.
0:04:55 > 0:04:59In the 19th century, oil from the whales' massive heads
0:04:59 > 0:05:01could make great fortunes.
0:05:06 > 0:05:08Whalemen targeted the calves first,
0:05:08 > 0:05:12knowing the rest of the pod would soon come to their aid...
0:05:12 > 0:05:15and into the range of the harpoons.
0:05:36 > 0:05:40But for one ship, the whales got their revenge.
0:05:40 > 0:05:46Without warning, a huge bull rammed the hull of the 87-foot Essex.
0:05:46 > 0:05:48CRASHING
0:05:59 > 0:06:04Within days, the broken ship was lost to the deep.
0:06:10 > 0:06:12With their ship gone,
0:06:12 > 0:06:16the 21 survivors squeezed into three whaleboats,
0:06:16 > 0:06:18which now became their lifeboats.
0:06:20 > 0:06:23The men salvaged what they could,
0:06:23 > 0:06:28but they were woefully ill-equipped for the trials that lay ahead.
0:06:44 > 0:06:48The survivors of the Essex were in virtually unexplored waters,
0:06:48 > 0:06:532,000 miles west of South America on the equator,
0:06:53 > 0:06:57almost as far from land as it's possible to be.
0:06:59 > 0:07:01They were about to find out
0:07:01 > 0:07:05just how challenging survival in the South Pacific can be.
0:07:07 > 0:07:11Unable to sail directly east because of the prevailing winds,
0:07:11 > 0:07:15they were forced south and into the area of the South Pacific
0:07:15 > 0:07:18known then as the Desolate Region.
0:07:24 > 0:07:30A vast, uncharted, windless ocean the size of Australia.
0:07:37 > 0:07:41These beautiful blue waters are the clearest in the world.
0:07:44 > 0:07:46But they are a watery desert,
0:07:46 > 0:07:50clear and blue because there is so little plankton,
0:07:50 > 0:07:53the key to all marine food chains.
0:07:54 > 0:07:59Plankton need nutrients, but most nutrients are locked in the deep,
0:07:59 > 0:08:03denied access to the surface by a layer of water called the thermocline,
0:08:03 > 0:08:06around 200 metres down.
0:08:10 > 0:08:14The little life that does exist at the surface seeks shelter,
0:08:14 > 0:08:17no matter how superficial it may be.
0:08:20 > 0:08:23In time, whole communities build on the flotsam.
0:08:24 > 0:08:27Barnacle larvae settle,
0:08:27 > 0:08:29along with miniature predators.
0:08:34 > 0:08:36Frogfish.
0:08:45 > 0:08:48On just a piece of drifting rope,
0:08:48 > 0:08:52tiny creatures may spend their entire lives.
0:09:00 > 0:09:03Three weeks on, the shipwreck survivors
0:09:03 > 0:09:06were in the heart of the Desolate Region,
0:09:06 > 0:09:08and in deep despair.
0:09:09 > 0:09:12In the boat's log, one of the survivors wrote,
0:09:12 > 0:09:15"The violence of raving thirst
0:09:15 > 0:09:19"has no parallel in the catalogue of human calamities."
0:09:21 > 0:09:24They had almost run out of rations,
0:09:24 > 0:09:27and despite being experienced sailors,
0:09:27 > 0:09:29failed to catch a single fish.
0:09:34 > 0:09:37But there are pockets of richness in the South Pacific.
0:09:37 > 0:09:41One was well known to the crew of the Essex
0:09:41 > 0:09:45and would have been in their reach, but for the prevailing winds.
0:09:45 > 0:09:48Lying over 700 miles off the coast of South America
0:09:48 > 0:09:51are the Galapagos Islands.
0:10:06 > 0:10:11Unlike the open ocean, the seas surrounding these 100 or so islands
0:10:11 > 0:10:13are bursting with life,
0:10:13 > 0:10:16with many creatures you wouldn't expect to find
0:10:16 > 0:10:19in tropical seas, like these sea lions.
0:11:02 > 0:11:04Despite sitting on the equator,
0:11:04 > 0:11:06the waters around the Galapagos are cooled
0:11:06 > 0:11:09by currents flowing all the way from Antarctica.
0:11:14 > 0:11:17It is this that allows the Galapagos to be home
0:11:17 > 0:11:20to the world's only tropical penguin.
0:11:30 > 0:11:33Tropical fish live here, too.
0:11:37 > 0:11:40Thanks to the nutrients carried by the cool current,
0:11:40 > 0:11:43there is an abundance of life.
0:11:46 > 0:11:48Unlike the open ocean,
0:11:48 > 0:11:53the water here is rich in plankton, feeding huge shoals of fish...
0:11:55 > 0:11:58..and even giant manta rays.
0:12:14 > 0:12:18Each sea lion needs over 6kg of fish a day.
0:12:21 > 0:12:24With shoals this size, it shouldn't be too difficult.
0:12:27 > 0:12:30But it's not easy picking one fish out of the crowd.
0:12:45 > 0:12:49The fish know there's safety in numbers, so for the sea lions
0:12:49 > 0:12:55the trick is to snip the shoal into smaller and smaller balls.
0:13:04 > 0:13:09Finally, a fish breaks for cover. It's what the sea lions have been waiting for.
0:13:09 > 0:13:13Crevices in the reef might seem to offer shelter.
0:13:13 > 0:13:16But that's no problem for the sea lions,
0:13:16 > 0:13:18who simply scare them out with bubbles.
0:13:27 > 0:13:30With the sea lions distracted, the fish regroup
0:13:30 > 0:13:33and the chase starts all over again.
0:14:16 > 0:14:18The riches of the Galapagos
0:14:18 > 0:14:22were something the survivors of the Essex could only fantasise about.
0:14:25 > 0:14:30One month into their ordeal, and still adrift in the Desolate Region,
0:14:30 > 0:14:33they were slowly starving.
0:14:37 > 0:14:42What the sailors didn't know was that the endless blue hides a secret.
0:14:44 > 0:14:50At dusk, huge areas of otherwise empty ocean are transformed.
0:14:54 > 0:14:58Squid shoot up from the depths to feed near the surface.
0:14:58 > 0:15:03Surprisingly, there are more squid in the ocean than fish...
0:15:04 > 0:15:08..and they take part in the greatest migration of animals on the Earth.
0:15:10 > 0:15:12Every night, a world of creatures
0:15:12 > 0:15:17rise up from the depths to dine on the small amounts of surface plankton.
0:15:20 > 0:15:25They are among the strangest-looking life forms on our planet.
0:15:35 > 0:15:37In this dark world, some are see-through,
0:15:37 > 0:15:40perhaps for camouflage.
0:15:40 > 0:15:46Some create their own light to communicate or lure in their prey.
0:15:48 > 0:15:51Others form inexplicable alliances.
0:15:51 > 0:15:54This young slipper lobster
0:15:54 > 0:15:58may be using this jelly as a buoyancy aid.
0:16:02 > 0:16:05Some of these ocean vagrants may offer protection,
0:16:05 > 0:16:08like this pyrosome is doing for the shrimp.
0:16:09 > 0:16:12In the world's deepest ocean,
0:16:12 > 0:16:14averaging over two-and-a-half miles deep,
0:16:14 > 0:16:18new species are constantly being discovered.
0:16:21 > 0:16:25Like this seahorse, never filmed before.
0:16:29 > 0:16:33At dawn, these little-known creatures
0:16:33 > 0:16:36retreat into the safety of the abyss.
0:16:41 > 0:16:44CLICKING
0:16:45 > 0:16:50But there are some predators that can follow them down.
0:16:54 > 0:16:58Short-finned pilot whales are accomplished deep-sea divers.
0:17:01 > 0:17:04Leaving the barren upper layers behind,
0:17:04 > 0:17:06they can swim over half a mile down
0:17:06 > 0:17:11and use their sonar to track the huge shoals of squid.
0:17:11 > 0:17:12CLICKING
0:17:23 > 0:17:26But they too are being tracked.
0:17:26 > 0:17:28FAST CLICKING
0:17:43 > 0:17:48Oceanic whitetip sharks, three metres long,
0:17:48 > 0:17:51and completely at home in the open ocean.
0:17:54 > 0:17:59They may not be able to dive deep enough to catch the squid themselves...
0:18:00 > 0:18:03..but that won't stop them hanging around for scraps.
0:18:04 > 0:18:07Or maybe they're sizing up the calf.
0:18:16 > 0:18:19This one, however, is well guarded
0:18:19 > 0:18:21by the bulls.
0:18:24 > 0:18:26CLICKING
0:18:45 > 0:18:50But in the endless blue, where the odds of finding a meal are so low,
0:18:50 > 0:18:53even the slimmest opportunity is worth a try.
0:18:56 > 0:18:59Perhaps this is why the oceanic whitetip
0:18:59 > 0:19:01is thought to be responsible
0:19:01 > 0:19:03for more attacks on shipwrecked sailors
0:19:03 > 0:19:06than any other shark in the Pacific.
0:19:08 > 0:19:12The survivors of the Essex were at the mercy of sharks.
0:19:12 > 0:19:14As one sailor wrote,
0:19:14 > 0:19:18"Our utmost efforts, which were at first directed to kill him for prey,
0:19:18 > 0:19:21"became, in the end, self-defence."
0:19:23 > 0:19:28Now, more than ever, they needed the salvation of land.
0:19:29 > 0:19:31SQUAWKING
0:19:37 > 0:19:40Seabirds would have been a ray of hope.
0:19:45 > 0:19:49While tropic birds can survive at sea for months on end,
0:19:49 > 0:19:54others, like frigate birds, return to roost every night,
0:19:54 > 0:19:57so are a sure sign of nearby land.
0:20:02 > 0:20:06Guided by the sun, stars and the Earth's magnetic field,
0:20:06 > 0:20:11seabirds navigate over thousands of miles of featureless ocean.
0:20:17 > 0:20:20They must all return to land to breed,
0:20:20 > 0:20:23often on little more than dots of sand,
0:20:23 > 0:20:27which makes their navigational skills even more impressive.
0:20:46 > 0:20:51The greatest ocean wanderer, with its two-metre wingspan,
0:20:51 > 0:20:53is the albatross.
0:20:56 > 0:21:00To find enough food for its oversized offspring,
0:21:00 > 0:21:05this black-footed albatross may have travelled a staggering 6,000 miles
0:21:05 > 0:21:09across the open ocean looking for hotspots of squid and fish.
0:21:10 > 0:21:12BEAKS CLATTER
0:21:15 > 0:21:17SQUAWKING
0:21:17 > 0:21:20The albatross nest
0:21:20 > 0:21:23on the tiny Hawaiian islands of French Frigate Shoals.
0:21:26 > 0:21:29This island may be only half a mile long,
0:21:29 > 0:21:34but it provides a base for around 300,000 seabirds.
0:21:34 > 0:21:35CHEEPING
0:21:38 > 0:21:41CHEEPING
0:21:44 > 0:21:47With food so hard to come by in the open ocean,
0:21:47 > 0:21:51newly hatched sooty tern chicks are easy pickings
0:21:51 > 0:21:53for the larger frigate birds.
0:21:58 > 0:22:01For hours on end, they survey the nesting grounds...
0:22:04 > 0:22:07..waiting for a chance to strike.
0:22:14 > 0:22:17SQUAWKING
0:22:17 > 0:22:21A mother tries desperately to protect her helpless chick.
0:22:23 > 0:22:25CHEEPING
0:22:29 > 0:22:31SQUAWKING
0:22:36 > 0:22:40But an unguarded chick is desperately vulnerable.
0:22:40 > 0:22:44It's what the frigate has been waiting for.
0:22:44 > 0:22:46FRENZIED SQUAWKING
0:22:46 > 0:22:49CHEEPING
0:22:56 > 0:22:58SQUAWKING AND CHEEPING
0:23:05 > 0:23:08CHEEPING
0:23:28 > 0:23:33No wonder the crew of the Essex called them the "man of war" birds.
0:23:33 > 0:23:36SQUAWKING
0:24:13 > 0:24:18For two weeks, the frigate birds keep up their relentless aerial assault
0:24:18 > 0:24:24until finally the sooty tern chicks are old enough to get away.
0:24:33 > 0:24:37Tropical islands are an obvious magnet for life.
0:24:38 > 0:24:41But things are just as busy underwater.
0:25:00 > 0:25:04Deep currents collide with these islands,
0:25:04 > 0:25:08forcing small but vital amounts of nutrients up from the depths.
0:25:12 > 0:25:17At 50 metres deep, sea fans are amongst the first to benefit.
0:25:26 > 0:25:31Closer to the surface, corals have sunlight to help them grow.
0:25:32 > 0:25:35And thanks to the smallest trickle of nutrients,
0:25:35 > 0:25:40a barren desert can bloom into an underwater oasis...
0:25:43 > 0:25:48..supporting a greater variety of life than any other ocean habitat.
0:26:19 > 0:26:23These coral reefs are a magnet for green turtles,
0:26:23 > 0:26:26offering a service not available in the open ocean -
0:26:26 > 0:26:30a good clean-up by a shoal of tangs.
0:26:40 > 0:26:43This work-over is far from cosmetic.
0:26:45 > 0:26:47As well as removing parasites,
0:26:47 > 0:26:52the cleaning stops the build-up of algae, so the turtle can swim freely.
0:26:56 > 0:26:58But it's also got to feel good!
0:27:13 > 0:27:15These turtles navigate their way
0:27:15 > 0:27:18across 1,000 miles of featureless ocean
0:27:18 > 0:27:21to reach these tiny, isolated islands.
0:27:22 > 0:27:26Perhaps they use their super-charged sense of smell
0:27:26 > 0:27:30to detect the traces of land in the ocean currents.
0:27:30 > 0:27:35Or maybe, like the seabirds, they too have an internal magnetic compass.
0:27:35 > 0:27:39But however they do it, when they're ready to nest,
0:27:39 > 0:27:44the females return to the very same beach on which they were born.
0:27:47 > 0:27:51Just as she arrives, others are preparing to leave.
0:27:56 > 0:28:00These seven-month-old black-footed albatross chicks
0:28:00 > 0:28:03have recently been abandoned by their parents.
0:28:03 > 0:28:08And now, driven by hunger, it's their time to get airborne.
0:28:21 > 0:28:23Unfortunately, with space at a premium,
0:28:23 > 0:28:26there is little room for manoeuvre,
0:28:26 > 0:28:29and they must make their maiden flights over water.
0:28:54 > 0:28:57But this is no place for a paddle.
0:29:06 > 0:29:07Tiger sharks.
0:29:11 > 0:29:14A dozen sharks, each over three metres long,
0:29:14 > 0:29:19have crossed hundreds of miles of ocean to attend this annual feast.
0:29:30 > 0:29:35Uncannily, these fearsome predators often arrive on the same day
0:29:35 > 0:29:37as the first chicks take to the air.
0:30:18 > 0:30:21Nothing could have prepared these chicks for such an encounter.
0:30:30 > 0:30:32Yet, despite looking like sitting ducks,
0:30:32 > 0:30:37inexperienced sharks find them hard to sink their teeth into.
0:30:52 > 0:30:56In an ocean where food is so hard to come by,
0:30:56 > 0:30:59the sharks can't afford to keep missing.
0:30:59 > 0:31:02They must quickly perfect their technique.
0:32:08 > 0:32:10For these albatross chicks,
0:32:10 > 0:32:14running the gauntlet of sharks may seem an impossible challenge,
0:32:14 > 0:32:18but the vast majority make it to a life in the open ocean.
0:32:25 > 0:32:30Specks of land were just as vital to our shipwrecked survivors.
0:32:34 > 0:32:37Not that they were easy to find.
0:32:37 > 0:32:41Only 1% of the Pacific is land.
0:32:46 > 0:32:52On 20th December, the sailors arrived on the Pitcairn Islands,
0:32:52 > 0:32:55over 2,000 miles from where they were first shipwrecked.
0:32:58 > 0:33:03Described by them as "a paradise before our very eyes",
0:33:03 > 0:33:07the starving sailors quickly set to work on the island's wildlife.
0:33:07 > 0:33:09THUMPING AND GRUNTING
0:33:11 > 0:33:14But the good times were not to last.
0:33:14 > 0:33:18Within a week, they had eaten all its seabirds.
0:33:22 > 0:33:26Leaving three of their group behind on this now impoverished island,
0:33:26 > 0:33:30the others chose to take their chances back at sea.
0:33:38 > 0:33:42They could have ridden the prevailing winds to the nearby Society Islands,
0:33:42 > 0:33:45but they were terrified of cannibals.
0:33:46 > 0:33:49Instead, they struck out east,
0:33:49 > 0:33:53to the distant shores of South America, 2,500 miles away...
0:33:55 > 0:33:59..and back into the dreaded Desolate Region.
0:34:10 > 0:34:15Bull sperm whales also undertake epic voyages across the Pacific.
0:34:30 > 0:34:32To reach such a gargantuan size,
0:34:32 > 0:34:36young bulls must leave their family groups in the tropics
0:34:36 > 0:34:39and go in search of richer pickings.
0:34:42 > 0:34:44SNORTING
0:34:44 > 0:34:49And so they head for the temperate seas of the higher latitudes.
0:34:53 > 0:34:56Crossing thousands of miles of ocean, many voyage
0:34:56 > 0:35:00to one of the greatest feeding grounds in the South Pacific -
0:35:00 > 0:35:02New Zealand.
0:35:27 > 0:35:31Its two main islands span almost 1,000 miles,
0:35:31 > 0:35:33and journeying south,
0:35:33 > 0:35:36its coastal waters become progressively cooler
0:35:36 > 0:35:38and weather-beaten.
0:35:44 > 0:35:47At 40 degrees latitude, severe westerly winds
0:35:47 > 0:35:51known as the Roaring Forties blast the coastline.
0:35:57 > 0:36:02Yet it is the foul weather that produces the abundance of life
0:36:02 > 0:36:05found in these cold waters.
0:36:05 > 0:36:07Storm-churning and colliding currents
0:36:07 > 0:36:10unlock the deep's great reserve of nutrients
0:36:10 > 0:36:12and send them to the surface.
0:36:23 > 0:36:28In these temperate seas, corals are replaced by forests of seaweed.
0:36:31 > 0:36:37In the summer, giant kelp can grow a staggering foot and a half a day.
0:37:17 > 0:37:21These waters may not support the diversity found in coral reefs,
0:37:21 > 0:37:25but they boast a far greater volume of animals.
0:37:35 > 0:37:38And a lot of fish means a lot of fish-eaters.
0:37:55 > 0:37:59Dusky dolphins off the coast of Kaikoura
0:37:59 > 0:38:02in New Zealand's South Island are so well fed
0:38:02 > 0:38:05that they can form superpods a thousand strong.
0:38:08 > 0:38:11SQUEAKING
0:38:15 > 0:38:17SQUEAKY BUZZING
0:39:07 > 0:39:10CLICKING AND BUZZING
0:39:26 > 0:39:28SNORTING
0:39:32 > 0:39:35After their epic journey from the tropics,
0:39:35 > 0:39:39the young bull sperm whales have finally made it.
0:39:46 > 0:39:50Sperm whales dive deeper than any other whale.
0:39:55 > 0:39:59They are drawn here by the fabulous wealth of deep-sea creatures -
0:39:59 > 0:40:01even the giant squid that lurk
0:40:01 > 0:40:04in the depths of a vast underwater canyon.
0:40:22 > 0:40:26To dive so deep and remain there for over an hour,
0:40:26 > 0:40:29whales must spend around ten minutes filling their lungs
0:40:29 > 0:40:32and blood with oxygen...
0:40:33 > 0:40:36..much to the interest of a passing fur seal.
0:40:46 > 0:40:50These young bulls will now spend another 15 years bulking up
0:40:50 > 0:40:52in the nutrient-rich seas.
0:41:07 > 0:41:09Only when they have become 30-tonne giants
0:41:09 > 0:41:12will the largest predators on Earth
0:41:12 > 0:41:16finally return to the tropics to compete for a mate.
0:41:23 > 0:41:28200 years ago, on the other side of the South Pacific,
0:41:28 > 0:41:32the journey of our whalemen was coming to an end.
0:41:44 > 0:41:4894 days after the ship was scuttled by a sperm whale,
0:41:48 > 0:41:51one of the whale boats was finally spotted
0:41:51 > 0:41:54400 miles off the coast of Chile.
0:41:58 > 0:42:01Only Captain Pollard and Ramsdell remained,
0:42:01 > 0:42:05gnawing on the bones of their dead shipmates.
0:42:08 > 0:42:10RIGGING CREAKS
0:42:10 > 0:42:1317 days earlier, in their darkest hour,
0:42:13 > 0:42:18they had drawn lots, executed and eaten them.
0:42:18 > 0:42:21WATER SLOSHING
0:42:24 > 0:42:28Of the three boats that were cast adrift,
0:42:28 > 0:42:30two resorted to cannibalism.
0:42:30 > 0:42:32One was never seen again.
0:42:40 > 0:42:43Navigating and surviving in this vast, remote wilderness
0:42:43 > 0:42:47had proved almost impossible for these experienced sailors.
0:42:52 > 0:42:56And at times, even the ultimate ocean travellers need help.
0:43:01 > 0:43:05Natural harbours may be safe havens for sailors,
0:43:05 > 0:43:10but for the migratory whales, they can be death traps.
0:43:10 > 0:43:14WAVES CRASHING
0:43:19 > 0:43:25A pod of 12 bull sperm whales has become fatally stranded.
0:43:26 > 0:43:31Was this stranding caused by one whale making a navigational error?
0:43:31 > 0:43:33No-one knows.
0:43:33 > 0:43:35But with social bonds so strong,
0:43:35 > 0:43:37the other whales can't help but follow.
0:44:00 > 0:44:01SNORTING
0:44:01 > 0:44:04One whale is still alive,
0:44:04 > 0:44:08but without sufficient water to support his incredible bulk,
0:44:08 > 0:44:10his internal organs will be crushed.
0:44:10 > 0:44:14Left like this, he will die within days.
0:44:20 > 0:44:22Thankfully, our attitude to sperm whales
0:44:22 > 0:44:26has changed from exploitation to conservation.
0:44:27 > 0:44:29A rescue team tries to dislodge him
0:44:29 > 0:44:32with waves from the bow of their boat.
0:44:47 > 0:44:50But he's held fast.
0:44:54 > 0:44:56His sunburnt skin quickly blisters.
0:45:02 > 0:45:05RUMBLING
0:45:12 > 0:45:15The only option left is to use nets.
0:45:33 > 0:45:36At last he's free.
0:45:42 > 0:45:46Badly weakened, he's chaperoned towards the harbour entrance.
0:45:48 > 0:45:50But he's not out of trouble yet.
0:45:50 > 0:45:54First, he must negotiate the rocky heads of the bay.
0:45:59 > 0:46:01INDISTINCT TWO-WAY RADIO CONVERSATION
0:46:18 > 0:46:24His sensitive skin, never designed to touch rock, is badly lacerated.
0:46:36 > 0:46:38He's through,
0:46:38 > 0:46:42and back into the safety of the endless blue.
0:46:55 > 0:46:59The sperm whales' story sums up the difficulties of surviving
0:46:59 > 0:47:01in this world of extremes.
0:47:07 > 0:47:11They succeed, thanks to their great stamina and extraordinary design.
0:47:15 > 0:47:19But at times, even the whales struggle to cope with the challenges
0:47:19 > 0:47:22of this vast ocean.
0:47:40 > 0:47:41Tiger sharks.
0:47:41 > 0:47:45They're one of the Pacific's most formidable predators.
0:47:47 > 0:47:52The goal was to film them hunting from above and below the water.
0:47:53 > 0:47:57This proved to be the team's greatest filming challenge.
0:48:03 > 0:48:07To film this behaviour, the team sailed 800 miles
0:48:07 > 0:48:11to one of the remotest islands in the Hawaiian chain - French Frigate Shoals.
0:48:11 > 0:48:15On this route, we should just pass...
0:48:15 > 0:48:18The timing was critical.
0:48:19 > 0:48:22For just two weeks a year,
0:48:22 > 0:48:25a dozen tiger sharks gather round this tiny island
0:48:25 > 0:48:29ready for the albatross chicks' maiden flights.
0:48:40 > 0:48:42So as not to disturb the bird colony,
0:48:42 > 0:48:45a scaffold tower was erected offshore
0:48:45 > 0:48:48in the middle of the shark-infested lagoon.
0:48:51 > 0:48:55This small filming platform was going to be the topside crew's base
0:48:55 > 0:48:57for the next ten days -
0:48:57 > 0:49:02a daunting prospect for landlubber cameraman John Aitchison.
0:49:04 > 0:49:07It's pretty scary being out here when they're really close.
0:49:07 > 0:49:10The platform wobbles when the waves hit it,
0:49:10 > 0:49:12and I wonder what would happen if I fell in.
0:49:13 > 0:49:15From this vantage point,
0:49:15 > 0:49:19producer Mark Brownlow was able to spot the sharks
0:49:19 > 0:49:21and direct the dive team to the action.
0:49:28 > 0:49:30Although experienced,
0:49:30 > 0:49:34cameraman Richard Woolocombe was understandably anxious.
0:49:34 > 0:49:37I have never dived with tiger sharks.
0:49:37 > 0:49:41And I'm incredibly excited on the one hand to see tiger sharks,
0:49:41 > 0:49:46but also somewhat reticent, knowing they have such a dangerous reputation.
0:49:46 > 0:49:52So shark expert and photographer Doug Perrine was hired to watch his back.
0:49:52 > 0:49:55And in one hand, I'll have an aluminium camera housing,
0:49:55 > 0:49:59and in another hand, I'll have this hi-tech shark billy.
0:49:59 > 0:50:03And then it's just a matter of giving them a little poke
0:50:03 > 0:50:07to let them know that you're alive and capable of defending yourself.
0:50:07 > 0:50:10The moment of truth had arrived.
0:50:12 > 0:50:15Bird on the water, 80 yards to the right.
0:50:15 > 0:50:18It was time to swim with tiger sharks.
0:50:23 > 0:50:27Pulling the boat up at a respectful distance from the bird,
0:50:27 > 0:50:31the divers' final approach was from underwater.
0:50:32 > 0:50:37To stop any surprise attacks from a shark beneath them,
0:50:37 > 0:50:39they hugged the sea bed.
0:50:41 > 0:50:43But the bird was long gone.
0:50:44 > 0:50:48They waited back-to-back for a tiger shark to show.
0:50:52 > 0:50:54None did.
0:50:54 > 0:50:56But as they surfaced,
0:50:56 > 0:50:58a shark appeared.
0:50:58 > 0:51:01Right behind you! Shark right behind you!
0:51:03 > 0:51:07It's a pretty intimidating sight to see a shark that big
0:51:07 > 0:51:10and that fat - it's a huge girth, absolutely incredible girth.
0:51:10 > 0:51:15Standing on his platform, John was perfectly placed to cover the action.
0:51:22 > 0:51:26But would Richard be quick enough to get to the birds before the sharks?
0:51:27 > 0:51:30- Oh!- Whoa!
0:51:30 > 0:51:33Just a fraction earlier, and we might've got the shot.
0:51:33 > 0:51:35This one's moving out towards it now.
0:51:39 > 0:51:42- The bird didn't fly off - he got eaten.- You're joking!
0:51:46 > 0:51:51With their highly tuned senses, the sharks were onto the chicks in seconds.
0:51:51 > 0:51:53Oh, man! We got so close!
0:51:53 > 0:51:58While the dive team lagged behind, John's success continued.
0:51:58 > 0:52:01That's it. Oh, no, it's got away!
0:52:01 > 0:52:04Shark came up and it's got away. Flying off.
0:52:05 > 0:52:08Phew! That was a lucky albatross!
0:52:09 > 0:52:14Each day, by mid-morning, the activity levels dropped.
0:52:14 > 0:52:18The birds stopped flying and there was no sign of the sharks.
0:52:20 > 0:52:23In the down time, the topside crew got the chance
0:52:23 > 0:52:26to get better acquainted with some new friends.
0:52:33 > 0:52:38I just think it's such an honour when birds treat you as a perch!
0:52:38 > 0:52:41But I'm quite glad it's not an albatross!
0:52:45 > 0:52:48The following day, it began to blow.
0:52:48 > 0:52:51WIND ROARS
0:52:51 > 0:52:55The strong wind's helping. It's giving them enough lift to take off
0:52:55 > 0:52:59and carry on flying to get back in. Oh, no. No...
0:53:00 > 0:53:04While unseasonal winds were good news for the birds,
0:53:04 > 0:53:07they made Richard's task much tougher.
0:53:08 > 0:53:11They're just taking off too much at the moment.
0:53:11 > 0:53:13This wind is too strong.
0:53:13 > 0:53:16It's not allowing us the time to get to the birds,
0:53:16 > 0:53:17or the sharks to get to them.
0:53:17 > 0:53:21After the wind came the rain.
0:53:21 > 0:53:24More bad news for the crew.
0:53:26 > 0:53:30But not for the chicks, who seemed invigorated by the downpour.
0:53:47 > 0:53:49The weather cleared up,
0:53:49 > 0:53:51but there was a new problem.
0:53:51 > 0:53:57A big tiger shark came in. From your perspective, I think you could see it more clearly than I.
0:53:57 > 0:54:01It was so poor visibility down there that I could just make it out,
0:54:01 > 0:54:03but I could see it was pretty big.
0:54:03 > 0:54:07Visibility's down to about 5ft. That's just not safe enough
0:54:07 > 0:54:09to dive with these big tiger sharks.
0:54:09 > 0:54:11We're going to have to call off the dive team.
0:54:11 > 0:54:13Very disappointing.
0:54:17 > 0:54:18The poor underwater visibility
0:54:18 > 0:54:22didn't seem to stop the sharks from finding their prey,
0:54:22 > 0:54:25giving John some concerns.
0:54:26 > 0:54:28I've got very mixed feeling about this.
0:54:28 > 0:54:33I don't really want to see the albatrosses eaten, but that's what I'm here to film.
0:54:33 > 0:54:36You can't help wishing the albatrosses will get away each time.
0:54:36 > 0:54:40I sort of cheer inside when they do. There's a shark, right in the shallows!
0:54:42 > 0:54:45John continued to film the action.
0:54:46 > 0:54:52But it was another three days before the visibility cleared sufficiently
0:54:52 > 0:54:53to make diving safe again.
0:54:59 > 0:55:01INDISTINCT INSTRUCTIONS FROM RADIO
0:55:15 > 0:55:17After days of practice,
0:55:17 > 0:55:21Richard was finally getting to the birds ahead of the sharks.
0:55:22 > 0:55:25- Yet still no success. - What did you see?
0:55:25 > 0:55:29The albatross gave us the run-around for a while,
0:55:29 > 0:55:34and then he finally decided he'd had enough of us and flew away.
0:55:34 > 0:55:37But why didn't the sharks take the bird?
0:55:37 > 0:55:40Were they now avoiding the divers?
0:55:40 > 0:55:43Whatever senses they're using, they've shown us
0:55:43 > 0:55:45that they want to stay away from us.
0:55:45 > 0:55:49Over the next two days, Doug's theory was confirmed,
0:55:49 > 0:55:51and Richard realised he had little to fear.
0:55:51 > 0:55:54The sharks are not interested in us.
0:55:54 > 0:55:58They're only interested in a slightly oilier substance
0:55:58 > 0:56:01in the form of a nice, fat, juicy albatross.
0:56:08 > 0:56:11I've got a very positive feeling about today.
0:56:11 > 0:56:14Conditions are improving, lots of sharks around,
0:56:14 > 0:56:17come to close to the boat - I think they're inviting us in.
0:56:17 > 0:56:21But filming a successful strike from underwater
0:56:21 > 0:56:23required a different strategy.
0:56:23 > 0:56:27No longer worried about being hit from below, Richard and Doug opted
0:56:27 > 0:56:31for the quieter approach of snorkelling at the surface...
0:56:35 > 0:56:38..only going under at the final moment.
0:56:42 > 0:56:45Would this new technique work?
0:56:47 > 0:56:49From the surface, the signs were good...
0:56:50 > 0:56:52Oh, whoa!
0:56:53 > 0:56:57..and John was once again following the action from his platform.
0:57:04 > 0:57:06SHRIEKING WHISTLE
0:57:06 > 0:57:08So how did it go for Richard?
0:57:09 > 0:57:12Unbelievable!
0:57:12 > 0:57:14That happened in a second!
0:57:14 > 0:57:16It was out of nowhere!
0:57:16 > 0:57:19My first hint that something was happening
0:57:19 > 0:57:22was when I saw a bunch of bubbles around the bird.
0:57:22 > 0:57:24Then I could kinda see the shape of the shark.
0:57:25 > 0:57:31That is THE most astonishing thing I've ever seen.
0:57:31 > 0:57:34But there was more to this story.
0:57:34 > 0:57:37You've got this incredible predator who's lurking around
0:57:37 > 0:57:39and you know he's out there.
0:57:39 > 0:57:43You know this animal is circling you. You can't see it, it can see you.
0:57:43 > 0:57:48And so you can't help now and again just to look away for a second,
0:57:48 > 0:57:52and in that split second on this occasion that I looked away, the shark hit.
0:57:52 > 0:57:57The power of the animal as it took the albatross
0:57:57 > 0:58:01was on the one hand terrifying, but on the other hand
0:58:01 > 0:58:03completely transfixing.
0:58:05 > 0:58:09I think that shot's going to haunt me for the rest of my life.
0:58:09 > 0:58:12Richard may only have filmed half the strike,
0:58:12 > 0:58:16but in the end, given the nervousness of the sharks,
0:58:16 > 0:58:18he was lucky to get even that.
0:58:42 > 0:58:44Subtitles by Red Bee Media Ltd
0:58:44 > 0:58:48E-mail subtitling@bbc.co.uk