0:00:31 > 0:00:34Australia - the land of sun, sea
0:00:34 > 0:00:37and surf.
0:00:39 > 0:00:45Its golden shores are a magnet for beach-lovers and thrill-seekers.
0:00:54 > 0:00:58Millions flock to explore the world's biggest coral reef.
0:00:58 > 0:01:04But while the Great Barrier Reef and Sydney Harbour are the classic images of Australian life,
0:01:04 > 0:01:07they're just the beginning.
0:01:17 > 0:01:21Leave behind those playgrounds of the crowded east coast
0:01:21 > 0:01:26and there's a much wilder party going on out there.
0:01:30 > 0:01:32This continent has a coastline
0:01:32 > 0:01:37that stretches from the hot northern tropics to the icy south.
0:01:39 > 0:01:44And all around are seas with the most astonishing variety of life.
0:01:56 > 0:01:59But these waters are challenging places to live.
0:02:02 > 0:02:05Only the toughest survive.
0:02:05 > 0:02:09Catching a wave is the easy bit.
0:02:18 > 0:02:22The seas around Australia are as harsh as the land itself.
0:02:22 > 0:02:26Only in very special places has marine life overcome the odds.
0:02:26 > 0:02:29The Great Barrier Reef is the one everyone knows
0:02:29 > 0:02:35but there's another coral extravaganza, on the other side of Australia.
0:02:37 > 0:02:40Here, the land is a desert and it hardly ever rains.
0:02:40 > 0:02:44There are no rivers flushing mud into the sea
0:02:44 > 0:02:47so the water stays crystal clear.
0:02:48 > 0:02:50It's perfect for growing corals,
0:02:50 > 0:02:54and all a stone's throw from the beach.
0:02:58 > 0:03:02Sandwiched between the desert shore and the open ocean,
0:03:02 > 0:03:07Ningaloo Reef is 260km of coral oasis.
0:03:09 > 0:03:14The outer reef wall encloses a self-contained world.
0:03:14 > 0:03:16Life thrives
0:03:16 > 0:03:19in the warmth of the sheltered lagoon.
0:03:23 > 0:03:25When conditions are this good,
0:03:25 > 0:03:29baby striped catfish gobble like mad to get a head start.
0:03:32 > 0:03:34But until they've grown up,
0:03:34 > 0:03:36they roll around the reef together.
0:03:36 > 0:03:40This way, they look bigger and scarier than they would alone.
0:03:54 > 0:03:57All the raw ingredients for life as a catfish -
0:03:57 > 0:04:01or as anything else - are trapped within the lagoon.
0:04:02 > 0:04:05..Until the autumn storms,
0:04:05 > 0:04:07when the nutrition-packed reef water
0:04:07 > 0:04:10spills out into the open sea.
0:04:11 > 0:04:13For just a brief period,
0:04:13 > 0:04:17the lifeless waters outside become a nourishing soup
0:04:17 > 0:04:21and dinner guests arrive from out of the blue.
0:04:38 > 0:04:40It's a whale shark.
0:04:42 > 0:04:46These giant ocean cruisers make long treks
0:04:46 > 0:04:50because food is so hard to find out in the clear tropical seas.
0:04:50 > 0:04:55But they can be sure of getting a spot of lunch round here.
0:04:55 > 0:04:58Ningaloo is the only place in the world
0:04:58 > 0:05:01where you can see them feeding so close to shore.
0:05:04 > 0:05:10Whale sharks aren't the only ones who've marked this event in their biological diary.
0:05:10 > 0:05:15Vast shoals of sardines appear out of the Indian Ocean
0:05:15 > 0:05:17to join Ningaloo's feast.
0:05:36 > 0:05:40They're tailed by predatory dogtooth tuna.
0:05:51 > 0:05:55Sharks appear - they're usually loners,
0:05:55 > 0:05:58but they'll gang up for a party like this.
0:06:09 > 0:06:13Sharks and tuna work the shoals, like dogs rounding up sheep,
0:06:13 > 0:06:18till they've pinned them against the shore in one massive, tight slick.
0:06:23 > 0:06:26The sardines look like easy meat,
0:06:26 > 0:06:29but the slick is now a solid wall of fish -
0:06:29 > 0:06:32it's hard for the predators to know where to start.
0:06:37 > 0:06:40Every time the sharks plough in,
0:06:40 > 0:06:43the little fish do their parting-the-waves trick.
0:06:43 > 0:06:45It's a dazzling defence.
0:06:47 > 0:06:52Tuna are like snipers - picking off fish from the edge of the huddle.
0:06:54 > 0:06:57But it's hard for the sharks -
0:06:57 > 0:07:00they can't get a grip on the vast, darting shoal.
0:07:22 > 0:07:26The bait ball is squeezed tighter, and even the sharks can't miss.
0:07:36 > 0:07:40Then, more heavyweight diners show up...
0:07:41 > 0:07:44The sardine shoal is now virtually on the beach,
0:07:44 > 0:07:47so surely out of reach of a huge Bryde's whale.
0:08:11 > 0:08:14The sharks are finally making a dent in the shoal,
0:08:14 > 0:08:19but it's nothing to what these monstrous whales can cram into their mouths.
0:08:54 > 0:08:57When the food runs out,
0:08:57 > 0:09:00the bounty hunters will drift away
0:09:00 > 0:09:03and the sea around here will return to hard times.
0:09:06 > 0:09:10Australia's north-west coast is pretty impoverished,
0:09:10 > 0:09:13and little, fertile pockets like Ningaloo are rare.
0:09:13 > 0:09:16But there ARE other surprises.
0:09:16 > 0:09:20Further south, there's a giant inlet called Shark Bay.
0:09:29 > 0:09:31It's surrounded by desert
0:09:31 > 0:09:37and, under a blazing sun, sea water evaporates off quicker than a boiling billycan.
0:09:40 > 0:09:43In the inner reaches of the bay,
0:09:43 > 0:09:47the concentrated water is twice as salty as the sea -
0:09:47 > 0:09:51and it doesn't get much tougher than that.
0:10:01 > 0:10:05There's nothing in this brine for these jellyfish to eat,
0:10:05 > 0:10:09so they've come up with a clever way to cope.
0:10:16 > 0:10:20Their tissues contain millions of plant cells
0:10:20 > 0:10:24that convert sunlight directly into food.
0:10:24 > 0:10:26These jellies are solar-powered.
0:10:30 > 0:10:32And since few predators
0:10:32 > 0:10:36can cope with living in this salty world,
0:10:36 > 0:10:39they're unhassled, and free to just soak up the sun.
0:10:56 > 0:11:00The shape of the coast has created a natural harbour,
0:11:00 > 0:11:02but on an Aussie scale.
0:11:02 > 0:11:05Inside, is a place like no other.
0:11:05 > 0:11:08Meadows of sea grass ripple over the sea bed.
0:11:10 > 0:11:15These are the greatest underwater prairies on the planet.
0:11:23 > 0:11:27Grass can tough it out anywhere, even in salty water.
0:11:33 > 0:11:35In fact, here it's perfect -
0:11:35 > 0:11:39the bay is calm, uniformly shallow, sunlit
0:11:39 > 0:11:42and the sandy bottom is ideal for grass roots.
0:11:42 > 0:11:45So it's sea grass all the way.
0:11:48 > 0:11:53This lush, sunny grassland is the foundation of all life here.
0:12:06 > 0:12:09There's plenty of food for sea horses...
0:12:09 > 0:12:13..and hiding places for the small and inexperienced.
0:12:16 > 0:12:21It's the tiny animals living around the stalks, as much as the grass itself,
0:12:21 > 0:12:25that offer such a good living to so many types of fish.
0:12:30 > 0:12:32Some look bizarre.
0:12:32 > 0:12:36The moth fish may seem overdesigned in its armour plating,
0:12:36 > 0:12:38but it has to be careful of enemies.
0:12:44 > 0:12:48One bite from a venomous sea snake would be lethal.
0:13:02 > 0:13:09But these are the real monsters of Shark Bay and they've spawned myths of giant proportions.
0:13:09 > 0:13:13Once upon a time, people thought they were mermaids.
0:13:17 > 0:13:21But it must have taken a desperate sailor to dream that one up!
0:13:23 > 0:13:26They're actually dugongs, vegetarian sea mammals,
0:13:26 > 0:13:30and there are over 10,000 of them in Shark Bay.
0:13:30 > 0:13:32There might be even more,
0:13:32 > 0:13:36if it weren't for the tiger sharks that give the bay its name.
0:13:36 > 0:13:39Babies stick close to Mum.
0:13:44 > 0:13:46They're sometimes called sea cows
0:13:46 > 0:13:49because they graze for eight hours a day
0:13:49 > 0:13:53and they need a huge gut to digest all that grass.
0:13:53 > 0:13:56No wonder they look poorly.
0:14:13 > 0:14:17Like all mammals, they have to take a breath from time to time.
0:14:17 > 0:14:20DUGONG BLOWS AIR
0:14:20 > 0:14:23..No worries in sea rarely deeper than 10m.
0:14:27 > 0:14:29Thanks to the meadows of sea grass,
0:14:29 > 0:14:33they lead a sheltered and stately life.
0:14:35 > 0:14:38Without the unusual shape of the coast,
0:14:38 > 0:14:41Shark Bay would be a sandy wasteland,
0:14:41 > 0:14:45much like the desert that surrounds it.
0:14:45 > 0:14:48Up north, there's another natural hot spot,
0:14:48 > 0:14:52but forged from a very different set of conditions
0:14:52 > 0:14:56Every year, Australia's top end is battered by the tropical monsoon.
0:14:57 > 0:15:00THUNDER RUMBLES
0:15:00 > 0:15:03AND WIND HOWLS
0:15:16 > 0:15:18The weather is wild
0:15:18 > 0:15:21and the currents are wicked.
0:15:35 > 0:15:38The ocean is funnelled violently through a bottleneck,
0:15:38 > 0:15:42the straits between Australia and the islands of Indonesia.
0:15:43 > 0:15:49The resulting tidal bulge is the highest anywhere in the tropics
0:15:49 > 0:15:51and it really stirs things up.
0:15:56 > 0:16:00At low tide, the sea drops a massive 12m,
0:16:00 > 0:16:05leaving the top end of Australia as one vast, steamy plain
0:16:05 > 0:16:07of mud and mangrove.
0:16:16 > 0:16:20The heavy monsoon rains have another vitalising effect -
0:16:20 > 0:16:23they flush out rich silt from the rivers
0:16:23 > 0:16:26and the coastal plains get a thick layer of mud.
0:16:26 > 0:16:29BIRDS TWITTER
0:16:29 > 0:16:32These muddy flats ooze with life
0:16:32 > 0:16:36and it's all desperate for cover, now the tide's gone out.
0:16:42 > 0:16:44And here's why.
0:16:50 > 0:16:53But with only six hours of feeding time till the tide comes in,
0:16:53 > 0:16:57mud skippers, golden ghost crabs and wading birds
0:16:57 > 0:16:59have to start in top gear.
0:17:09 > 0:17:12They're all desperate to get to the water's edge,
0:17:12 > 0:17:16where the receding tide has exposed a slap-up feast.
0:17:17 > 0:17:20A million migrating birds refuel
0:17:20 > 0:17:25by sifting the warm silt for worms, snails and shellfish.
0:17:33 > 0:17:37Some have travelled over 15,000km to feed here,
0:17:37 > 0:17:42because these are the richest tidal mud flats in the world.
0:17:43 > 0:17:46But, like a gold rush,
0:17:46 > 0:17:48things can get lawless.
0:17:48 > 0:17:51The sanderlings aren't above a bit of daylight robbery.
0:18:08 > 0:18:12But the villains of the beach are the seagulls.
0:18:23 > 0:18:25On an exposed mud flat,
0:18:25 > 0:18:29it's impossible to keep your treasures to yourself.
0:18:32 > 0:18:35This sand eel is quite a prize.
0:18:41 > 0:18:44GULL SQUAWKS ANGRILY
0:19:04 > 0:19:07There's no justice round here(!)
0:19:07 > 0:19:10And, with the returning tide, the crab has no time
0:19:10 > 0:19:13to make up for his loss.
0:19:28 > 0:19:31While crabs can dig in under the racing tide,
0:19:31 > 0:19:36waders have to cosy up at the top of the shrinking beach.
0:19:50 > 0:19:56At high tide, the sea is brimming again and all you see is a desert shore.
0:19:56 > 0:19:59But, in a few hours, the tide will recede,
0:19:59 > 0:20:01the mud flats will be revealed
0:20:01 > 0:20:04and the action will start all over again.
0:20:09 > 0:20:12Northern Australia sits under the tropics.
0:20:12 > 0:20:16Like a massive generator, it drives the climate of the land,
0:20:16 > 0:20:20but it also has a powerful effect on Australia's seas.
0:20:23 > 0:20:27The Leeuwin Current is a river of warm water from the north
0:20:27 > 0:20:29that pumps down the west coast,
0:20:29 > 0:20:33working its way into the cooler seas of the south.
0:20:33 > 0:20:38It brings a lick of tropical warmth, but it doesn't bring any nutrients.
0:20:38 > 0:20:42They've already been used up by other marine life.
0:20:49 > 0:20:54This warm, empty current snakes into the Great Australian Bight,
0:20:54 > 0:20:59the broad bay that arcs around Australia's southern side.
0:20:59 > 0:21:02These coastal seas should be heaving with life,
0:21:02 > 0:21:06as full of fish as the north Atlantic.
0:21:06 > 0:21:11The cliffs should be screaming with nesting sea birds, but they're not.
0:21:20 > 0:21:26The Leeuwin current drives a wedge of tepid water between the coast and the adjacent southern ocean.
0:21:29 > 0:21:34As a result, the sea's as infertile as the land above.
0:21:34 > 0:21:38Only extreme animals can live down here.
0:21:41 > 0:21:46To find enough food, this Australian sea lion has just returned
0:21:46 > 0:21:49from three days of long dives along the coast.
0:21:49 > 0:21:53By any seal's standards, that's a marathon.
0:21:56 > 0:22:00And so, on the last leg, she deserves an easy ride in.
0:22:19 > 0:22:22SEA LION CALLS
0:22:22 > 0:22:25She tells her pup she's back.
0:22:25 > 0:22:27It's desperate for a feed.
0:22:32 > 0:22:38They can only live here because of the unconventional way they bring up the pups.
0:22:38 > 0:22:43These babies are huge. Other young seals would have been weaned by now,
0:22:43 > 0:22:47but Australian sea lion pups suckle for over a year and a half,
0:22:47 > 0:22:50way longer than their relatives.
0:22:52 > 0:22:55A good, fat start is the only way to go
0:22:55 > 0:22:58for a life in impoverished seas.
0:23:01 > 0:23:06Even so, Aussie sea lions live for just 12 years.
0:23:06 > 0:23:10It's the shortest lifespan of any seal.
0:23:16 > 0:23:19When the mothers go back out to sea,
0:23:19 > 0:23:24the pups make the most of their extended childhood.
0:23:28 > 0:23:31ROARS
0:24:02 > 0:24:04A coastal lagoon,
0:24:04 > 0:24:06out of reach of predatory sharks,
0:24:06 > 0:24:10is a safe place to try life in the water.
0:24:35 > 0:24:39These Aussie sea lions depend on their mothers for years,
0:24:39 > 0:24:44but they're not pampered - they have to prepare for life on the edge.
0:24:44 > 0:24:49As adults, they make record-breaking dives, just to get enough to eat,
0:24:49 > 0:24:53so they need this time to develop stamina, too.
0:24:53 > 0:24:56But it looks as if they have a bit of fun along the way.
0:25:17 > 0:25:21In these barren waters, it's hard for anything to make a living,
0:25:21 > 0:25:26so what can possibly attract an animal the size of a whale?
0:25:26 > 0:25:29She's come here to have a baby.
0:25:29 > 0:25:31The warmth of the Leeuwin current
0:25:31 > 0:25:36has created a lovely, whale-sized birthing pool.
0:25:40 > 0:25:44Southern right whales spend most of the year in the subantarctic,
0:25:44 > 0:25:49but the water's too cold and wild down there for a vulnerable baby.
0:25:49 > 0:25:52They come to the protected bays
0:25:52 > 0:25:55of the Australian Bight to rear their calves.
0:25:57 > 0:26:00WHALE CALLS
0:26:09 > 0:26:12But this is one hungry baby
0:26:12 > 0:26:16and it needs mother's milk to build up its strength.
0:26:18 > 0:26:21Breastfeeding is demanding -
0:26:21 > 0:26:24the baby could suck its mother dry.
0:26:24 > 0:26:27So what is SHE doing for food?
0:26:27 > 0:26:30She sorted that out months ago,
0:26:30 > 0:26:33by fattening up in the rich southern ocean.
0:26:33 > 0:26:38Over the summer, she ate her way through two tons of krill a day.
0:26:44 > 0:26:47It gave her enough energy to swim 2,000km,
0:26:47 > 0:26:51give birth, produce thousands of litres of milk...
0:26:51 > 0:26:56and then guide her calf back to the subantractic -
0:26:56 > 0:26:58all without taking another bite.
0:27:01 > 0:27:03WHALES CALL
0:27:11 > 0:27:14Most animals, such as the giant cuttlefish,
0:27:14 > 0:27:16don't venture such distances.
0:27:21 > 0:27:26But they have to find food in these impoverished waters.
0:27:26 > 0:27:30Their favourite prey is thin on the ground,
0:27:30 > 0:27:33so they live and hunt alone.
0:27:38 > 0:27:40First, they mesmerise their victim.
0:27:51 > 0:27:53Then, they take aim.
0:27:53 > 0:27:56It must be like looking down the barrel of a gun.
0:28:05 > 0:28:08They're deadly accurate -
0:28:08 > 0:28:11but not so hot in reverse.
0:28:17 > 0:28:20Cuttlefish only get together in the autumn.
0:28:20 > 0:28:25The Great Australian Bight has rocky reefs, which are vital in the breeding season,
0:28:25 > 0:28:30and cuttles gather in their thousands to size each other up.
0:28:34 > 0:28:38Giant cuttlefish are the biggest of their kind -
0:28:38 > 0:28:41males can grow over a metre long
0:28:41 > 0:28:44and they're the ones that command centre stage.
0:28:47 > 0:28:49There's lots of showing off.
0:28:49 > 0:28:53These flashy signals sort the men from the boys.
0:29:00 > 0:29:02Holding ground is everything.
0:29:02 > 0:29:06This big male wants to control a certain spot.
0:29:08 > 0:29:12It's where the females will come to lay their eggs.
0:29:15 > 0:29:17Other males try to muscle in.
0:29:34 > 0:29:38These upstarts don't seem to be getting the message,
0:29:38 > 0:29:42so the defending male throws his weight around a bit.
0:29:50 > 0:29:52The females are much daintier,
0:29:52 > 0:29:58but they always search for the biggest male - he usually holds the key to the best egg chamber.
0:30:04 > 0:30:06After all the bravado,
0:30:06 > 0:30:08he shows his tender side.
0:30:29 > 0:30:32That's the romance out of the way.
0:30:32 > 0:30:35Now it's back to guard duty.
0:30:35 > 0:30:39Rivals never give up, and the big male wants to make sure
0:30:39 > 0:30:43those are HIS babies under that rock.
0:30:50 > 0:30:54To the east of here, life in the sea goes up a gear.
0:30:56 > 0:30:59The warm Leeuwin current is running out of steam...
0:31:03 > 0:31:07..and the cold southern ocean is beginning to take charge.
0:31:08 > 0:31:12This force from the south has chiselled out huge limestone stacks.
0:31:12 > 0:31:17The Twelve Apostles stand as if in reverence to the power of the sea.
0:31:23 > 0:31:25Off the south-east of Australia,
0:31:25 > 0:31:30these colder seas also start to shape life BENEATH the waves.
0:31:30 > 0:31:35It's chilly, but it's paradise compared to the waters of the Bight.
0:31:39 > 0:31:42It's as if the handbrake has finally been taken off
0:31:42 > 0:31:45and life can really motor.
0:31:45 > 0:31:48There are over 1,000 different types of kelp, alone.
0:31:57 > 0:32:00Forests of giant kelp grow at top speed
0:32:00 > 0:32:03in these ideal conditions.
0:32:03 > 0:32:08The southern ocean pumps in all the basic ingredients.
0:32:08 > 0:32:10With a good dose of sunlight,
0:32:10 > 0:32:14and the plentiful nutrients you get in cool waters,
0:32:14 > 0:32:17these seaweed trees can grow half a metre a day.
0:32:25 > 0:32:28Sometimes, they reach 50 metres,
0:32:28 > 0:32:31taller than most of the trees on land.
0:32:40 > 0:32:45But it isn't just the luxuriant growth that makes this so special.
0:32:45 > 0:32:48It's the remoteness.
0:32:48 > 0:32:51It's been remote for so long,
0:32:51 > 0:32:55that most of the plants and animals are found nowhere else on Earth.
0:32:57 > 0:32:59Even by Australian standards,
0:32:59 > 0:33:03this weedy sea dragon looks out of this world.
0:33:04 > 0:33:08Like the kangaroos and koalas on land,
0:33:08 > 0:33:13the sea animals have been caught up in their own evolutionary bubble.
0:33:18 > 0:33:22Gliding through the seaweed, on its peculiar fins,
0:33:22 > 0:33:26it proves that not all dragons are myths.
0:33:35 > 0:33:40The curious little hand fish would rather walk than swim.
0:33:48 > 0:33:52It uses ITS strange fins to stroll along the sea floor,
0:33:52 > 0:33:55saving tail power for when it's really needed.
0:34:04 > 0:34:08The leafy sea dragon has a dress code all its own.
0:34:08 > 0:34:11It's modelled itself on the local seaweeds.
0:34:18 > 0:34:22These dragons are nearly half a metre long,
0:34:22 > 0:34:24but they easily go unnoticed.
0:34:24 > 0:34:29This outrageous fashion statement is the perfect camouflage.
0:34:37 > 0:34:41And these are not your typical Aussie males -
0:34:41 > 0:34:45with sea dragons, it's the fathers that carry the eggs.
0:34:50 > 0:34:54He makes quite sure that the offspring don't drift off.
0:34:54 > 0:35:00It's crucial - they must hatch out and grow up against this same matching background.
0:35:00 > 0:35:04They'd stick out like a sore thumb anywhere else,
0:35:04 > 0:35:09so they're trapped forever in this corner of Australia.
0:35:09 > 0:35:13Other residents are more cosmopolitan.
0:35:13 > 0:35:16They're not so tied to this strange place.
0:35:16 > 0:35:21In fact, some make every effort to get their offspring out of here.
0:35:24 > 0:35:26And the ocean currents will help.
0:35:28 > 0:35:33After sundown, a female lobster sets out across the reef.
0:35:35 > 0:35:40Under her tail is a precious cargo of tiny larvae.
0:35:43 > 0:35:47She's looking for the highest point on the reef,
0:35:47 > 0:35:50to send them on their way.
0:35:53 > 0:35:56The top spot is always the most popular,
0:35:56 > 0:36:01but once all the females are in position, they wait.
0:36:02 > 0:36:07There are fewer predators around in the hour before dawn,
0:36:07 > 0:36:10so only then do they cast off their brood.
0:36:40 > 0:36:45The water's more turbulent up here at the top of the reef,
0:36:45 > 0:36:47so it's hard to hold her hands down.
0:36:54 > 0:36:58With this odd and elegant way of giving birth,
0:36:58 > 0:37:00lobsters have colonised the oceans.
0:37:11 > 0:37:15The lucky ones get sucked into the powerful ocean current.
0:37:15 > 0:37:18It only clips the corner of Australia,
0:37:18 > 0:37:22so its effects largely pass the country by.
0:37:22 > 0:37:25But it hits New Zealand square on,
0:37:25 > 0:37:28so there, its impact is stronger.
0:37:33 > 0:37:37New Zealand and Australia used to be joined together,
0:37:37 > 0:37:41but they drifted apart millions of years ago,
0:37:41 > 0:37:44and now their seas are very different.
0:37:51 > 0:37:55The waters around New Zealand are topped up by nutrients
0:37:55 > 0:37:58washed from this fertile land,
0:37:58 > 0:38:02so they're richer and support more life.
0:38:04 > 0:38:07Like this massive colony of gannets.
0:38:12 > 0:38:14SQUAWKING
0:38:20 > 0:38:25Each summer, 8,000 pairs will raise a family here.
0:38:27 > 0:38:31And it's all based on the fabulous fisheries
0:38:31 > 0:38:36of pilchards, anchovies and jack mackerel in the surrounding sea.
0:38:46 > 0:38:48They have to pinpoint the catch,
0:38:48 > 0:38:53but once they get their bearings, each hit is a bull's-eye.
0:39:05 > 0:39:09Gannets slice into the water at 150 kilometres an hour,
0:39:09 > 0:39:13which means they can score fish 10 metres below the surface.
0:39:13 > 0:39:16If the fish go deeper,
0:39:16 > 0:39:21the gannets just wait for the arrival of the back-up squad.
0:39:23 > 0:39:31Common dolphins harass the sardines from below, pinning them up against the surface.
0:39:35 > 0:39:39And that puts them back into gannet range.
0:40:01 > 0:40:07Although these numbers are impressive, gannets are citizens of the world.
0:40:07 > 0:40:11After all, you can see the same spectacle in British waters.
0:40:11 > 0:40:16But New Zealand has been sitting out on its own for a very long time,
0:40:16 > 0:40:21and it has some wildlife wonders that are truly unique.
0:40:22 > 0:40:27Hector's dolphins are only found around the New Zealand coast.
0:40:32 > 0:40:35They're also tiny -
0:40:35 > 0:40:40at just over a metre long, they're the miniatures of the dolphin world.
0:40:40 > 0:40:45They spend all their lives in the shallow water near the beach.
0:40:46 > 0:40:51Further out, they'd be a mere snack for a shark or a killer whale.
0:40:53 > 0:40:55But they don't need to go anywhere.
0:40:55 > 0:41:01The bountiful Southern Ocean brings a total lifestyle package right to the door.
0:41:49 > 0:41:54The huge swell is a reminder that New Zealand's southern tip
0:41:54 > 0:41:59is in the firing line of the coldest, wildest ocean in the world.
0:42:10 > 0:42:14It's one of the most fertile seas on Earth,
0:42:14 > 0:42:18but sea birds can't breed out here - they need land.
0:42:23 > 0:42:30The Snares Islands are the last specks of rock connected to the Australian continental shelf -
0:42:30 > 0:42:35sure ground in the midst of a full-throttle ocean.
0:42:45 > 0:42:49In the great sweep of open sea between Australia and Antarctica,
0:42:49 > 0:42:53Snares crested penguins have no shortage of food.
0:42:53 > 0:42:56It's dry land that's at a premium.
0:43:11 > 0:43:17Every summer, the waters around these isolated islands swarm with penguins.
0:43:17 > 0:43:21They're gathering to get the next generation under way.
0:43:24 > 0:43:30The Snares Islands are the only rocks around where these birds can raise their young.
0:43:30 > 0:43:35Twice a day, the adults must return to the nests to feed their chicks,
0:43:35 > 0:43:39and they have to run the gauntlet of pirates.
0:43:47 > 0:43:5250 metres out, the returning penguins raft together on the surface
0:43:52 > 0:43:57until sheer numbers give them the confidence to make a dive for sure.
0:43:59 > 0:44:03In the melee, head-ons can't be avoided.
0:44:08 > 0:44:14Under the water, penguins are just too nippy for Hooker's sea lions.
0:44:14 > 0:44:19This one's probably on the lookout for a weak or injured bird.
0:44:30 > 0:44:36Fit penguins have no trouble covering the last stretch of open water.
0:44:39 > 0:44:43Landing is trickier, but these birds are fearless.
0:45:16 > 0:45:20Snares penguins have to be sure-footed -
0:45:20 > 0:45:24their twice-daily commute includes a sheer wall of granite.
0:45:28 > 0:45:31Penguins may not be the most elegant climbers,
0:45:31 > 0:45:36but with their low centre of gravity, strong claws and sheer doggedness,
0:45:36 > 0:45:39they get there in the end.
0:45:45 > 0:45:51At the top, there's the rush-hour traffic and muddy forest trails to negotiate.
0:45:51 > 0:45:54CHATTERING AND CHIRRUPING
0:45:57 > 0:46:02Then they have to pinpoint the caws of their own out of the colonial din.
0:46:02 > 0:46:07Only then can Mum and Dad bring home the bacon,
0:46:07 > 0:46:09or in this case, regurgitated squid.
0:46:19 > 0:46:25Two months and two tired parents later, the chicks are ready for the sea.
0:46:27 > 0:46:32The journey begins enthusiastically as they all head for the water...
0:46:32 > 0:46:37but it takes a while to find your feet.
0:46:54 > 0:46:58Maybe it's better to give it just a few more minutes.
0:47:00 > 0:47:05Snares penguins are just one of the many resilient animals
0:47:05 > 0:47:09that have risen above the challenges in these southern seas.
0:47:10 > 0:47:16These tough little birds have to overcome one more obstacle -
0:47:16 > 0:47:21getting into the water's a triumph of substance over style.
0:47:49 > 0:47:53Desert waters, tricky currents and sheer isolation
0:47:53 > 0:47:58have all helped shape the diversity of marine life down under.
0:48:00 > 0:48:05These are waters filled with surprises and delights
0:48:05 > 0:48:10Hardship has simply brought out the best in the strange southern seas.
0:48:21 > 0:48:25Next week, Wild Down Under takes you out bush
0:48:25 > 0:48:31into Australia's strange and colourful gumtree country.
0:48:31 > 0:48:34These spectacular woodlands are full of life
0:48:34 > 0:48:38and home to Australia's weirdest and most charismatic animals.
0:48:38 > 0:48:42From giant trees to miniature possums,
0:48:42 > 0:48:47we travel the landscape that's the very essence of Australia.
0:48:47 > 0:48:51Subtitles by Mairi Macleod & Alison Rae - BBC Broadcast 2003