0:00:10 > 0:00:15In the heart of south-east Asia is an ancient kingdom...
0:00:17 > 0:00:21..with over 3,000km of coastline.
0:00:24 > 0:00:27But beyond its golden shores,
0:00:27 > 0:00:30there are secret worlds.
0:00:37 > 0:00:39Home to mysterious creatures...
0:00:41 > 0:00:44..and forest giants...
0:00:51 > 0:00:53This is a fast-changing country
0:00:53 > 0:00:57where East and West collide.
0:01:04 > 0:01:08People and animals must work together to survive...
0:01:11 > 0:01:14..forming unique relationships.
0:01:18 > 0:01:21A spiritual land,
0:01:21 > 0:01:24full of magic and wonder.
0:01:31 > 0:01:34This is Thailand.
0:01:50 > 0:01:52South-west Thailand.
0:01:52 > 0:01:57A wild paradise of limestone castes,
0:01:57 > 0:02:02golden beaches and dense forests.
0:02:03 > 0:02:08Along this rugged coast are some close-knit families.
0:02:10 > 0:02:15A troupe of 30 long-tailed macaques has made this their home.
0:02:29 > 0:02:33This youngster has relied on his mother for the last six months.
0:02:35 > 0:02:39But he's now at an age where he needs a more varied diet.
0:02:42 > 0:02:47Trouble is, this is one of Thailand's most extreme locations...
0:02:55 > 0:02:59..a vertical rock face, 50 metres high.
0:03:03 > 0:03:07Up here, good food is scarce.
0:03:07 > 0:03:11Bark and leaves provide little energy.
0:03:15 > 0:03:20Macaques are the most resourceful and wide-ranging monkeys on earth
0:03:20 > 0:03:24and have learned to take advantage of every opportunity.
0:03:29 > 0:03:33But this one involved a precarious commute.
0:03:43 > 0:03:47It's especially risky for a mother carrying an infant.
0:04:03 > 0:04:06For a young macaque still learning the ropes,
0:04:06 > 0:04:10having a tail longer than your body gives you the edge.
0:04:10 > 0:04:15It can both grip and act as a counterbalance.
0:04:19 > 0:04:23This daily descent is well worth the effort.
0:04:29 > 0:04:33Across Thailand, there are thousands of Buddhist temples
0:04:33 > 0:04:38and families like this get a surprisingly warm welcome.
0:04:38 > 0:04:40MAN SPEAKS OWN LANGUAGE
0:04:50 > 0:04:54Thai Buddhists have a unique relationship with nature.
0:05:06 > 0:05:11For them, every living thing contributes something to the world
0:05:11 > 0:05:13and deserves respect.
0:05:22 > 0:05:26This compassionate relationship is the perfect example
0:05:26 > 0:05:31of the spiritual connection so special in southern Thailand
0:05:31 > 0:05:37where humans are not set apart from nature, but live within it.
0:05:44 > 0:05:49There are other welcome benefits for the macaques who visit this temple.
0:05:49 > 0:05:55A chance to cool off and have some fun in the heat of the day.
0:06:05 > 0:06:08Southern Thailand is a natural paradise
0:06:08 > 0:06:11for people and animals alike.
0:06:12 > 0:06:15Hidden coves and scattered islands
0:06:15 > 0:06:20give it a total of 3,000km of coastline.
0:06:20 > 0:06:25Its western shores have been carved and shaped by the Andaman Sea.
0:06:29 > 0:06:34Here, astonishing limestone castes have been created -
0:06:34 > 0:06:38towering stacks of ancient shell and coral.
0:06:43 > 0:06:47This one stands 50 metres tall.
0:06:47 > 0:06:49Once part of the seabed,
0:06:49 > 0:06:53it was thrust up by extreme geological forces.
0:06:57 > 0:07:00The power of the sea and seasonal rains
0:07:00 > 0:07:04continue to sculpt this dramatic landscape.
0:07:13 > 0:07:17Every year, millions of people are drawn here.
0:07:17 > 0:07:20Most come to relax.
0:07:22 > 0:07:25Others are here for an adrenaline rush.
0:07:27 > 0:07:31Ao Nang Tower stands nearly 100 metres high.
0:07:35 > 0:07:38The ultimate challenge for thrill seekers.
0:07:45 > 0:07:50People come from all over the world to climb these extraordinary cliffs.
0:07:56 > 0:07:59But the locals have been scaling them for centuries.
0:08:05 > 0:08:08And it's not thrills they seek.
0:08:10 > 0:08:12It's natural treasure.
0:08:17 > 0:08:19These men have their sights set on
0:08:19 > 0:08:23a cave hundreds of metres up a vertical cliff face.
0:08:30 > 0:08:33Inside, there's a hidden prize,
0:08:33 > 0:08:36but reaching it is fraught with danger.
0:08:43 > 0:08:46There's no hi-tech climbing gear here.
0:08:46 > 0:08:49Just old ropes and local knowledge.
0:08:57 > 0:09:01They must also navigate a treacherous interior...
0:09:07 > 0:09:12..a ten-metre drop into total darkness.
0:09:21 > 0:09:24This is what they're after.
0:09:28 > 0:09:33Tiny, almost translucent birds nests.
0:09:33 > 0:09:37They may not look much, but in Asia,
0:09:37 > 0:09:40they're a highly sought-after delicacy.
0:09:41 > 0:09:46Eating birds nest soup is thought to boost the immune system,
0:09:46 > 0:09:49improve skin complexion and fight ageing.
0:09:52 > 0:09:57It's no wonder one kilogram of nests is worth over 2,000.
0:10:01 > 0:10:06Wild nest collecting has been going on for over 500 years.
0:10:06 > 0:10:09Recently, the safety and sustainability
0:10:09 > 0:10:11has been brought into question.
0:10:14 > 0:10:17But an unexpected answer was found.
0:10:19 > 0:10:21BIRDSONG PLAYS FROM LOUDSPEAKERS
0:10:22 > 0:10:26Thousands of loudspeakers in the town of Pak Phanang
0:10:26 > 0:10:29play birdsong at full blast.
0:10:33 > 0:10:37Tweeting 24 hours a day, seven days a week.
0:10:42 > 0:10:47What was once a traditional fishing town is now at the heart
0:10:47 > 0:10:50of a brand-new industry -
0:10:50 > 0:10:52bird nest farming.
0:10:56 > 0:10:58Windows have been sealed up.
0:10:58 > 0:11:02The darker inside, the better.
0:11:06 > 0:11:10All to accommodate a very particular resident.
0:11:14 > 0:11:17The edible nest swiftlet.
0:11:19 > 0:11:24During the breeding season, the salivary glands of the swifts expand
0:11:24 > 0:11:26and produce extra thick saliva.
0:11:29 > 0:11:32Layer upon layer over 40 days,
0:11:32 > 0:11:35the birds craft it into a cup-like nest.
0:11:42 > 0:11:45These new nesting sites are helping this bird
0:11:45 > 0:11:49make a good recovery after years of decline.
0:11:55 > 0:11:58Each day, as the swiftlets are out feeding,
0:11:58 > 0:12:01farmers like Mr Mu check the nests.
0:12:07 > 0:12:10He waits until pairs have bred successfully
0:12:10 > 0:12:13and the chicks have fledged
0:12:13 > 0:12:17before collecting their precious nests.
0:12:28 > 0:12:31The people of Pak Phanang have a risk-free,
0:12:31 > 0:12:35sustainable way to harvest the nests
0:12:35 > 0:12:40and the swiftlets have a new network of nesting sites.
0:12:45 > 0:12:47Across southern Thailand,
0:12:47 > 0:12:52people and animals are finding new ways to live together
0:12:52 > 0:12:57and that sometimes requires a bit of ingenuity.
0:13:00 > 0:13:03Over 50km off the mainland
0:13:03 > 0:13:07lie two of the remotest groups of Thai islands,
0:13:07 > 0:13:10Similan and Surin.
0:13:14 > 0:13:17With crystal clear waters
0:13:17 > 0:13:20and golden beaches...
0:13:24 > 0:13:28..this place might look like paradise,
0:13:28 > 0:13:31but dragons roam these shores.
0:13:38 > 0:13:42A giant monitor lizard,
0:13:42 > 0:13:44two metres long...
0:13:46 > 0:13:48..looking for food.
0:13:59 > 0:14:04It tastes and smells the air with its 30-centimetre tongue,
0:14:04 > 0:14:08sensing even the slightest hint of a meal.
0:14:23 > 0:14:27Hermit crabs protect themselves by hiding their soft bodies
0:14:27 > 0:14:30in the abandoned shells of other creatures.
0:14:38 > 0:14:42They live up to 30 years, so as they grow,
0:14:42 > 0:14:45they need to upsize their homes.
0:14:49 > 0:14:52But there's something of a housing crisis on this island.
0:14:57 > 0:15:00These idyllic hideaways are a magnet for tourists,
0:15:00 > 0:15:05who find it hard to resist taking the occasional souvenir.
0:15:09 > 0:15:14Every time a shell is removed, a crab loses a potential new home.
0:15:19 > 0:15:24So these canny crabs have found another source of housing.
0:15:29 > 0:15:34Each evening, the rangers clear the beaches, piling up the litter.
0:15:36 > 0:15:40And now the crabs do something extraordinary.
0:15:52 > 0:15:56This hermit has found herself a more modern home...
0:15:57 > 0:15:59..in a mackerel tin.
0:16:03 > 0:16:08With so few shells around, it's an ingenious solution.
0:16:15 > 0:16:18And she's not alone.
0:16:18 > 0:16:20This is a fast-growing trend.
0:16:33 > 0:16:38An aluminium fizzy drink can makes a lightweight home
0:16:38 > 0:16:40that's worth fighting for.
0:16:49 > 0:16:52Life in the mackerel tin isn't ideal...
0:16:54 > 0:16:56..and the local rangers know it.
0:16:59 > 0:17:02So they leave seashells near the rubbish piles
0:17:02 > 0:17:05to help the homeless crustaceans.
0:17:08 > 0:17:12The crab normally winds its body into the spiral of a shell.
0:17:14 > 0:17:18It's far harder to grip a straight and slippery can.
0:17:25 > 0:17:27There are plenty of options.
0:17:27 > 0:17:31It's all about finding a snug fit.
0:17:41 > 0:17:44Well, she can be picky if she wants.
0:17:44 > 0:17:48Moving house is an important decision.
0:18:04 > 0:18:07At last, the perfect home.
0:18:17 > 0:18:20It might look like paradise,
0:18:20 > 0:18:25but living along this coastline requires great resourcefulness.
0:18:27 > 0:18:32In southern Thailand, long-tailed macaques are sometimes known as
0:18:32 > 0:18:35"Ling Thalay" - sea monkeys.
0:18:40 > 0:18:42And it's not hard to see why.
0:19:01 > 0:19:04But this isn't just about having a good time.
0:19:09 > 0:19:14Like their temple-visiting cousins, they've got a clever plan.
0:19:14 > 0:19:18They've adapted their lives to the rhythm of the sea.
0:19:21 > 0:19:26And twice a day, low tide reveals a feast -
0:19:26 > 0:19:28nutritious shellfish.
0:19:30 > 0:19:33Trouble is, shells are tough to crack.
0:19:37 > 0:19:42But ever resourceful, these macaques have found a smart solution.
0:19:47 > 0:19:52They've worked out that rocks make perfect shellfish hammers.
0:20:04 > 0:20:09Although clearly some macaques are a little smarter than others.
0:20:16 > 0:20:21Either way, low tide provides a seafood bounty.
0:20:26 > 0:20:30Stone tool use is a rare skill among monkeys.
0:20:30 > 0:20:36But these macaques can only benefit from it by being completely in tune
0:20:36 > 0:20:38with the cycles of nature...
0:20:41 > 0:20:45..something many of Thailand's human residents aspire to.
0:20:55 > 0:21:00The south of the country is rich in Buddhist temples and shrines.
0:21:00 > 0:21:02MONKS CHANT
0:21:08 > 0:21:13Sacred places where monks seek to understand themselves and the world
0:21:13 > 0:21:14in which they live.
0:21:20 > 0:21:25Buddhist principles place human life in the context of a series of cycles
0:21:25 > 0:21:29like those in the natural world.
0:21:35 > 0:21:37For more than 2,000 years,
0:21:37 > 0:21:42the full moon has been celebrated as an embodiment of this idea.
0:21:48 > 0:21:53This celebration of the full moon is embraced by visitors to Thailand,
0:21:53 > 0:21:56but their version is rather more exuberant.
0:22:00 > 0:22:01LOUD MUSIC BLARES
0:22:04 > 0:22:09Koh Phangan's famous beach party is a rite of passage for backpackers
0:22:09 > 0:22:11passing through southern Thailand.
0:22:17 > 0:22:20Partygoers are bathed in ultraviolet light
0:22:20 > 0:22:23and their fluorescent body paint glows.
0:22:26 > 0:22:30But hidden from view, just below the water's surface,
0:22:30 > 0:22:33there's an equally vibrant display.
0:22:35 > 0:22:38By shining the same ultraviolet light underwater,
0:22:38 > 0:22:41an unexpected wonder is revealed.
0:22:47 > 0:22:51These tropical waters are home to an abundance of coral reefs.
0:22:53 > 0:22:57A protein within them absorbs the ultraviolet light,
0:22:57 > 0:23:00emitting back a whole new spectrum.
0:23:04 > 0:23:07These corals are all fluorescing.
0:23:12 > 0:23:14First discovered in the 1930s,
0:23:14 > 0:23:17scientists are still debating why this happens.
0:23:20 > 0:23:22One theory is that fluorescent proteins
0:23:22 > 0:23:25might act as a type of sunblock...
0:23:27 > 0:23:30..protecting the coral from the sun's intense rays.
0:23:50 > 0:23:54But it isn't just corals that glow under ultraviolet.
0:24:00 > 0:24:05It's possible that other creatures are able to see this show, too,
0:24:05 > 0:24:08and use it to their advantage.
0:24:12 > 0:24:16One reef resident's behaviour seems to support this theory.
0:24:21 > 0:24:26The scorpion fish is an ambush predator
0:24:26 > 0:24:29so camouflage is key.
0:24:37 > 0:24:41Passing fish need to beware.
0:24:41 > 0:24:45Come too close and his cavernous mouth will suck them up
0:24:45 > 0:24:47in a split second.
0:24:59 > 0:25:02For this scorpion fish,
0:25:02 > 0:25:07red fluorescing algae appears to be the perfect disguise.
0:25:17 > 0:25:22Southern Thailand's secret worlds go far beyond its dazzling coastline.
0:25:39 > 0:25:44In the very centre of the peninsula is a freshwater lake called
0:25:44 > 0:25:47Cheow Lan, surrounded by great mountains.
0:25:56 > 0:26:01Limestone peaks intercept moisture-laden clouds,
0:26:01 > 0:26:04producing much-needed water for this rainforest.
0:26:07 > 0:26:103,000 square kilometres of it.
0:26:17 > 0:26:24It is home to an exceptional diversity of plants and animals.
0:26:24 > 0:26:27For 12 million years, the forest has
0:26:27 > 0:26:30echoed to strange and haunting sounds.
0:26:30 > 0:26:32BIRDS CHIRPING
0:26:32 > 0:26:37WINGS BEATING
0:26:37 > 0:26:39The wing beats of a giant.
0:26:42 > 0:26:44The great hornbill.
0:26:47 > 0:26:50WINGS BEATING
0:26:51 > 0:26:53BIRD CRIES
0:27:02 > 0:27:07For this male, it's an important time of year.
0:27:07 > 0:27:12Inside this nest hole is his lifelong partner.
0:27:12 > 0:27:16There's a slit just wide enough for a bill.
0:27:16 > 0:27:20But she's sealed in and won't come out until her chicks fledge
0:27:20 > 0:27:22in four months' time.
0:27:24 > 0:27:29For now, she's completely reliant on him to find food for them all.
0:27:47 > 0:27:51A long bill makes fruit easier to reach.
0:28:03 > 0:28:07It's tossed to the back of the throat and stored in a pouch.
0:28:15 > 0:28:18Remarkably, hornbills can carry
0:28:18 > 0:28:20over 250 berries at a time.
0:28:31 > 0:28:34Delicately regurgitating one at a time,
0:28:34 > 0:28:37he eases his beak through the narrow hole.
0:28:45 > 0:28:48This devoted couple have raised
0:28:48 > 0:28:52chicks in this tree for over a decade.
0:28:52 > 0:28:55And because they might live to the age of 40,
0:28:55 > 0:28:59they should be back here for many more years to come.
0:29:18 > 0:29:20On the east coast of Southern Thailand,
0:29:20 > 0:29:23there is another secret world far from
0:29:23 > 0:29:26the tourist trails, teeming with wildlife.
0:29:29 > 0:29:34Flat coastal plains are home to four expansive lagoons,
0:29:34 > 0:29:38covering over 8,000 square kilometres.
0:29:43 > 0:29:45In Thailand's largest lake,
0:29:45 > 0:29:48local people are finding unique ways to make a living.
0:29:50 > 0:29:52Somjai is a farmer.
0:29:52 > 0:29:55He's raising the only large animals to be found here.
0:30:02 > 0:30:06Somewhere amongst this expanse is his herd of water buffalo.
0:30:06 > 0:30:09GRUNTING
0:30:13 > 0:30:16Although their wild ancestors are native to Thailand,
0:30:16 > 0:30:19these are domesticated buffalo.
0:30:21 > 0:30:24Somjai lets them live a mostly wild life.
0:30:28 > 0:30:31But in the evening, he tracks them down.
0:30:39 > 0:30:42In the shallowest parts of the lake, punting is the only option.
0:30:45 > 0:30:50The buffalo spend the day feeding on the rich aquatic plants.
0:31:14 > 0:31:16In the 40 degree heat,
0:31:16 > 0:31:19a mud bath cools them off and repels insects.
0:31:23 > 0:31:27The buffaloes' splayed hooves stop them sinking into the soft ground.
0:31:30 > 0:31:36But the constant exposure to water can be damaging.
0:31:36 > 0:31:40So he must round them up and steer them into a dry pen for the night.
0:31:40 > 0:31:43HE SHOUTS
0:31:53 > 0:31:55For Somjai, this work is about much
0:31:55 > 0:31:57more than making a living.
0:32:07 > 0:32:10The dry pen not only protects their feet,
0:32:10 > 0:32:13but gives them a chance to rest for the night.
0:32:19 > 0:32:22This free range partnership also has
0:32:22 > 0:32:25unexpected benefits for the wider ecosystem.
0:32:28 > 0:32:31Ploughing their way through the wetlands,
0:32:31 > 0:32:33spreading seeds as they go,
0:32:33 > 0:32:36the buffalo help important plants to regenerate.
0:32:42 > 0:32:46Carpets of lotus flowers create a haven for over a million birds...
0:32:50 > 0:32:53..making this a wetland of global importance.
0:33:02 > 0:33:06It's the perfect place for specialists,
0:33:06 > 0:33:08those with a light step...
0:33:09 > 0:33:11..and fast reactions.
0:33:18 > 0:33:21This purple swamp hen may look ungainly,
0:33:21 > 0:33:23but he's got a secret weapon.
0:33:26 > 0:33:31Huge feet to spread his body weight over the floating foliage.
0:33:35 > 0:33:39This helps a lot when stealth is not your style.
0:33:46 > 0:33:50He also has a particular taste in food,
0:33:50 > 0:33:53unwittingly helping to protect his habitat.
0:33:58 > 0:34:03Golden apple snails aren't native to Thailand and can harm natural
0:34:03 > 0:34:05habitats when numbers boom.
0:34:07 > 0:34:10Luckily, swamp hens love them.
0:34:17 > 0:34:19If they can find them.
0:34:29 > 0:34:34A secure footing is vital when you're trying to haul in your catch.
0:34:40 > 0:34:44Long toes mean a foot can act as a hand.
0:34:51 > 0:34:55Purple swamp hens are perfectly adapted to this environment,
0:34:55 > 0:34:57and in a small way,
0:34:57 > 0:35:01these accidental conservationists are helping to preserve it.
0:35:08 > 0:35:10These aren't the only animals
0:35:10 > 0:35:14helping to conserve the natural beauty of Southern Thailand.
0:35:21 > 0:35:25This is Kui Buri National Park.
0:35:27 > 0:35:29Formerly thick forest,
0:35:29 > 0:35:32it was cleared for farmland and the wildlife forced out.
0:35:34 > 0:35:36In the 1990s,
0:35:36 > 0:35:38public support for Buddhist-inspired
0:35:38 > 0:35:40environmental principles started to grow.
0:35:42 > 0:35:47Respecting the natural world was not simply a spiritual notion.
0:35:47 > 0:35:49It had to become a reality.
0:35:54 > 0:35:58In 1999, the government gave this area back to nature.
0:35:58 > 0:36:02BELLOWING
0:36:07 > 0:36:10These native elephants reclaimed land
0:36:10 > 0:36:14and have had a remarkable impact on the ecosystem.
0:36:21 > 0:36:27Asian elephants need to eat 150kg of food each day.
0:36:33 > 0:36:37They eat over 50 different plant types,
0:36:37 > 0:36:41spreading seeds far and wide in their dung,
0:36:41 > 0:36:43replanting Kui Buri's forest.
0:36:43 > 0:36:45BELLOWING
0:36:53 > 0:36:55And by pushing through the undergrowth,
0:36:55 > 0:37:00they create pathways for smaller animals like sambar deer.
0:37:03 > 0:37:08They also give birds an opportunity to pick off scattering insects.
0:37:19 > 0:37:23Elephants were allowed to rebuild the ecosystem
0:37:23 > 0:37:26and they have done just that,
0:37:26 > 0:37:29creating a wild paradise.
0:37:35 > 0:37:37Turning this habitat back over to
0:37:37 > 0:37:40the animals has restored the balance.
0:37:42 > 0:37:44But in other habitats,
0:37:44 > 0:37:47sometimes only human intervention will do.
0:38:01 > 0:38:04Although these boards are being used for a bit of fun,
0:38:04 > 0:38:07the Thai people invented them long before the wake board.
0:38:10 > 0:38:12And when used in the traditional way,
0:38:12 > 0:38:15they are a vital form of transport,
0:38:15 > 0:38:19and the best way to get safely around a mangrove swamp at low tide.
0:38:28 > 0:38:31These men are here on urgent business.
0:38:40 > 0:38:43Mangroves once covered much of Thailand's coastline...
0:38:46 > 0:38:49..but since the 1960s,
0:38:49 > 0:38:53half have been uprooted to make way for shrimp farms.
0:38:53 > 0:38:56When people began to realise the devastating impact
0:38:56 > 0:38:59of shrimp farming on the landscape,
0:38:59 > 0:39:03they started looking more closely at this vitally important ecosystem.
0:39:09 > 0:39:13Decomposing leaves provide valuable nutrients
0:39:13 > 0:39:15which support a rich biodiversity.
0:39:21 > 0:39:25Mangroves also act as a barrier between the land and the sea,
0:39:25 > 0:39:30protecting low-lying communities from storms and coastal flooding.
0:39:31 > 0:39:34They produce seeds that are buoyant,
0:39:34 > 0:39:37floating away and germinating in far away places.
0:39:41 > 0:39:43As their roots grow outwards,
0:39:43 > 0:39:45they trap sediment,
0:39:45 > 0:39:47and are one of the few habitats
0:39:47 > 0:39:49that can actually build up the coastline.
0:39:55 > 0:39:58Cutting down the trees is now illegal,
0:39:58 > 0:40:01and over the last 30 years,
0:40:01 > 0:40:03volunteers from all over the south
0:40:03 > 0:40:05have been replanting the mangrove forests.
0:40:09 > 0:40:13Little by little, this crucial habitat is reclaiming the land.
0:40:16 > 0:40:19And mud skippers are moving in -
0:40:19 > 0:40:21a tangible sign of recovery.
0:40:29 > 0:40:33Seeing them here means there is a healthy supply of food.
0:40:35 > 0:40:38And a good tidal flow creating lots of fresh puddles
0:40:38 > 0:40:40to keep their skin wet.
0:40:45 > 0:40:46For ecologists,
0:40:46 > 0:40:48seeing them living in a new forest
0:40:48 > 0:40:52is a sign the ecosystem is functioning once again.
0:40:55 > 0:40:59And this mangrove restoration has far-reaching effects.
0:41:07 > 0:41:12The coral reef owes its clear waters to the mangroves' natural filtering
0:41:12 > 0:41:14of silt and pollutants.
0:41:21 > 0:41:24South-east Asia has more coral reef
0:41:24 > 0:41:26than any other region of the world.
0:41:31 > 0:41:33Lying at the heart of this area,
0:41:33 > 0:41:37Thai waters are home to more than 2,000 types of fish...
0:41:41 > 0:41:43..such as the moray eel,
0:41:43 > 0:41:45clownfish,
0:41:45 > 0:41:47and cuttlefish.
0:41:50 > 0:41:52When the reef is in balance,
0:41:52 > 0:41:55every individual plays a crucial role.
0:41:59 > 0:42:03The crown of thorns starfish grazes on the fastest-growing coral,
0:42:03 > 0:42:06giving the slower-growing corals a chance to catch up.
0:42:11 > 0:42:16Long-spined sea urchins feed on algae,
0:42:16 > 0:42:18clearing the way for coral growth.
0:42:26 > 0:42:29But the reef is a delicate ecosystem
0:42:29 > 0:42:32that can easily be knocked out of balance.
0:42:35 > 0:42:38Pollution and a loss of natural predators
0:42:38 > 0:42:42can cause starfish and urchin numbers to explode.
0:42:47 > 0:42:51Both are covered in venomous spines.
0:42:58 > 0:43:03But there is one renowned reef resident able to take them on.
0:43:08 > 0:43:10The titan triggerfish.
0:43:12 > 0:43:15They've got a fearsome reputation...
0:43:22 > 0:43:25..aggressively defending their patch of reef.
0:43:36 > 0:43:38A sea urchin's spines are no
0:43:38 > 0:43:41protection against teeth like these.
0:43:51 > 0:43:55Although the crown of thorns is well protected on top,
0:43:55 > 0:43:57it has a soft underside.
0:44:04 > 0:44:07Titan triggerfish play an important role
0:44:07 > 0:44:10in keeping numbers at healthy levels.
0:44:13 > 0:44:15And with this much food around,
0:44:15 > 0:44:18it's a great place to start a family.
0:44:25 > 0:44:29This couple have a little bundle of eggs to care for.
0:44:36 > 0:44:42While the female blows water over the eggs to oxygenate them,
0:44:42 > 0:44:44the male is on guard patrol.
0:44:48 > 0:44:52This sort of parental care might be surprising,
0:44:52 > 0:44:55but it's vitally important they protect
0:44:55 > 0:44:57the next generation of reef helpers.
0:45:07 > 0:45:10All the creatures here play their part.
0:45:10 > 0:45:13And this has a direct influence on the open ocean.
0:45:19 > 0:45:22When the coral and other reef animals spawn,
0:45:22 > 0:45:24it helps to feed the plankton.
0:45:30 > 0:45:34Some of this is swept up by large filter feeding animals...
0:45:36 > 0:45:38..like the manta ray...
0:45:41 > 0:45:43..and whale shark.
0:45:53 > 0:45:57The rest can drift far away,
0:45:57 > 0:45:59forming a floating food supply.
0:46:03 > 0:46:06This not only supports life under the sea,
0:46:06 > 0:46:08but also above it.
0:46:12 > 0:46:17Fish is the most important source of protein in Southern Thailand.
0:46:22 > 0:46:24Almost two million Thai people keep
0:46:24 > 0:46:26the country supplied with this staple.
0:46:32 > 0:46:35In this village on the east coast of Thailand,
0:46:35 > 0:46:38Bang, his wife Patima,
0:46:38 > 0:46:42and their son Thongchai rely on a good daily catch.
0:46:53 > 0:46:56Early every morning, they head out to sea.
0:47:19 > 0:47:22Before they cast their nets,
0:47:22 > 0:47:25there's a sign from nature they always hope to see...
0:47:26 > 0:47:30..something that helps guide them to the biggest shoals of fish.
0:47:58 > 0:48:02This is the Indo-Pacific humpback dolphin,
0:48:02 > 0:48:06a species found in coastal waters from India to Australia.
0:48:08 > 0:48:12It's sometimes called the pink dolphin.
0:48:14 > 0:48:16Grey in their juvenile years,
0:48:16 > 0:48:20they slowly lose this colour in blotches,
0:48:20 > 0:48:23turning bright pink when they fully mature.
0:48:28 > 0:48:31These unusual-looking dolphins
0:48:31 > 0:48:33scour the coastline in search of the
0:48:33 > 0:48:35small fish that feed on plankton.
0:48:37 > 0:48:41Anchovies are a favourite for dolphin and fishermen alike.
0:48:52 > 0:48:54And today it's a good haul.
0:49:06 > 0:49:10There's one more thing they want to do before heading back to shore.
0:49:24 > 0:49:26Across their range,
0:49:26 > 0:49:30pink dolphins often forge special relationships with people.
0:49:39 > 0:49:43Southern Thailand is a natural paradise
0:49:43 > 0:49:47where people and nature are deeply connected.
0:49:50 > 0:49:52For many Thai people,
0:49:52 > 0:49:55their existence is no more important than those creatures
0:49:55 > 0:49:57with whom they share their world.
0:50:02 > 0:50:04Habitat to habitat,
0:50:04 > 0:50:08surprising connections and partnerships run deep.
0:50:09 > 0:50:13This is a place that draws people from all over the world
0:50:13 > 0:50:16to enjoy its beauty.
0:50:16 > 0:50:18It's a wild wonderland
0:50:18 > 0:50:21full of unexpected surprises.
0:50:37 > 0:50:42The coral reefs of southern Thailand are world-renowned.
0:50:43 > 0:50:46But there's an animal that lives on
0:50:46 > 0:50:49the reef that strikes fear in all who enter the water.
0:50:58 > 0:51:01It's definitely the fish that everyone is scared of.
0:51:01 > 0:51:04Like, we have some sharks, no problem.
0:51:06 > 0:51:09I don't want to get on the wrong side of them.
0:51:09 > 0:51:13This woman got bitten or rammed on her head or something.
0:51:13 > 0:51:16And there was just blood pouring down her head.
0:51:16 > 0:51:18The titan triggerfish.
0:51:21 > 0:51:23It may be only 60 centimetres long,
0:51:23 > 0:51:26but its huge teeth are built to bite
0:51:26 > 0:51:28through coral and shell.
0:51:30 > 0:51:34During the breeding season, they're particularly aggressive
0:51:34 > 0:51:36when caring for their eggs.
0:51:36 > 0:51:40And this is what the BBC crew were here to film.
0:51:43 > 0:51:48Producer Lara Bickerton has just one week to get what she needs.
0:51:50 > 0:51:52Seeing a triggerfish at all would be a start on this shoot.
0:51:53 > 0:51:57But cameramen Johnny Rogers and Simon Enderby are highly skilled
0:51:57 > 0:51:59underwater cinematographers.
0:52:03 > 0:52:08The waters surrounding Thailand are famous for their incredible clarity.
0:52:10 > 0:52:11But not today.
0:52:14 > 0:52:17No triggers. No titans.
0:52:17 > 0:52:21No titans. Visibility about no more than five metres.
0:52:21 > 0:52:24Apparently the visibility is better on the other side of the island,
0:52:24 > 0:52:26so shall we go and give that a go?
0:52:26 > 0:52:28Yeah.
0:52:28 > 0:52:30It's a good plan, but the crew don't get far.
0:52:30 > 0:52:34ENGINE RUMBLES
0:52:37 > 0:52:41We're just on our way to another dive site and found out our boat's
0:52:41 > 0:52:44broken down. The ironic result is the boat that is now towing us is
0:52:44 > 0:52:46actually towing us faster than what this boat
0:52:46 > 0:52:48was doing under its own power.
0:52:52 > 0:52:56At last Simon gets a second dive in.
0:52:59 > 0:53:01Got it?
0:53:02 > 0:53:05Although the visibility is still poor,
0:53:05 > 0:53:07he captures the odd glimpse of a titan.
0:53:13 > 0:53:16They are certainly around.
0:53:16 > 0:53:18They're there, but we just can't see them.
0:53:18 > 0:53:20Visibility is too bad.
0:53:23 > 0:53:25The crew are told normal weather patterns
0:53:25 > 0:53:27are running three weeks late,
0:53:27 > 0:53:30and that could be what's reducing the visibility.
0:53:33 > 0:53:35Things only get worse.
0:53:40 > 0:53:42Lara is increasingly concerned.
0:53:45 > 0:53:48High winds, heavy rain and rough seas.
0:53:50 > 0:53:52The team need their luck to change.
0:53:58 > 0:54:01Three days later, the storm passes.
0:54:02 > 0:54:05The crew hope the water visibility has improved, too.
0:54:08 > 0:54:12The challenge now is not finding more triggerfish,
0:54:12 > 0:54:15but filming a complete behavioural sequence.
0:54:16 > 0:54:20So the crew focus their attention at a site where the triggerfish's prey,
0:54:20 > 0:54:23the crown of thorns starfish, is most abundant.
0:54:27 > 0:54:31It's a place that marine biologist Spencer Arnold knows well.
0:54:37 > 0:54:41Sometimes starfish numbers can explode and damage the reef.
0:54:41 > 0:54:44So Spencer and the volunteers from New Heaven Dive School
0:54:44 > 0:54:47work hard to remove them.
0:54:49 > 0:54:53But there are still plenty left for the triggerfish.
0:54:53 > 0:54:56The titan triggerfish will eat a crown of thorns sea star.
0:54:56 > 0:54:58So obviously very,
0:54:58 > 0:55:01very important keystone species on the island of Koh Tao in terms of
0:55:01 > 0:55:03controlling these, these pest species.
0:55:06 > 0:55:10The challenge for the crew now is finding and filming the triggerfish.
0:55:10 > 0:55:12With so little time left,
0:55:12 > 0:55:16Lara decides to form a tag team, with both Johnny and Simon working
0:55:16 > 0:55:20back-to-back, maximising their time underwater.
0:55:21 > 0:55:26Johnny Rogers is also using a re-breather diving system,
0:55:26 > 0:55:30allowing him to spend over two hours at a time underwater.
0:55:32 > 0:55:34And as soon as Simon comes out,
0:55:34 > 0:55:36Johnny gets in.
0:55:40 > 0:55:44This allows them eight hours a day of uninterrupted filming.
0:55:48 > 0:55:52With the visibility much better, the team make progress.
0:55:53 > 0:55:56Johnny captures footage of a triggerfish
0:55:56 > 0:55:59attacking the soft underside of a crown of thorns starfish.
0:56:02 > 0:56:04It's a great start to the sequence.
0:56:09 > 0:56:11We got her on a crown of thorns.
0:56:11 > 0:56:14- Did you?- Yeah.- Awesome.- Great news.
0:56:14 > 0:56:16And Johnny's seen a triggerfish.
0:56:16 > 0:56:19Well, I've seen one before, but not on this trip.
0:56:19 > 0:56:21It's only taken four days.
0:56:23 > 0:56:25The team are soon back underwater,
0:56:25 > 0:56:27making the most of the time they have left.
0:56:29 > 0:56:33And Johnny gets a remarkable bit of behaviour no one expected.
0:56:42 > 0:56:46The triggerfish bites each individual spine off the sea urchin
0:56:46 > 0:56:48before devouring the whole thing.
0:56:51 > 0:56:53Finally we're actually getting somewhere.
0:56:57 > 0:56:59Simon captures the final bit of the puzzle.
0:57:02 > 0:57:04It's when the titans are guarding
0:57:04 > 0:57:07their nests they get most aggressive.
0:57:07 > 0:57:10But this couple are surprisingly chilled,
0:57:10 > 0:57:14letting Simon get an intimate view of the female aerating her eggs.
0:57:20 > 0:57:22Well, patience finally paid off.
0:57:22 > 0:57:24That's the closest I've ever come to a nesting
0:57:24 > 0:57:27titan triggerfish in my entire life.
0:57:28 > 0:57:32Male and female. Male, we found the male first, defending his territory.
0:57:32 > 0:57:36Thought, OK. Actually swam over the female looking at the male,
0:57:36 > 0:57:38didn't notice that. I went, "Oh, hello."
0:57:38 > 0:57:42So I was basically this much from her, puffing away on her eggs.
0:57:44 > 0:57:46Sunshine, blue water,
0:57:46 > 0:57:48target animals.
0:57:48 > 0:57:50Amazing, amazing news.
0:57:50 > 0:57:53I am so chuffed at that.
0:57:53 > 0:57:54Today has paid off.
0:57:56 > 0:57:59The team finally had the conclusion they needed.
0:58:00 > 0:58:03And along the way learned that if you catch
0:58:03 > 0:58:07this notorious fish on a good day, they're remarkably easy-going.
0:58:14 > 0:58:17Next time, we head to Thailand's bustling capital.
0:58:20 > 0:58:26Here, spirituality can be found in human and animal relationships.
0:58:26 > 0:58:28Both likely and unlikely.
0:58:30 > 0:58:32This is the very heart of Thailand.
0:58:32 > 0:58:37Home to mysterious giants and striking beauty.