1 00:00:23,400 --> 00:00:25,400 Almost 200 years ago, 2 00:00:25,400 --> 00:00:29,700 whilst walking these very paths in the English countryside 3 00:00:29,800 --> 00:00:33,000 and observing the banks and meadows near his home, 4 00:00:33,000 --> 00:00:34,900 Charles Darwin developed 5 00:00:35,000 --> 00:00:37,500 his ground-breaking ideas about evolution, 6 00:00:37,600 --> 00:00:40,400 casting a new light on the natural world 7 00:00:40,400 --> 00:00:43,300 and opening our eyes to its true wonder. 8 00:00:44,600 --> 00:00:48,400 Since then, we've explored almost every part of the planet 9 00:00:48,400 --> 00:00:52,500 and seen nature in its astounding variety. 10 00:00:52,500 --> 00:00:55,300 But there's still much to discover. 11 00:00:58,300 --> 00:01:00,800 In this new series of Planet Earth... 12 00:01:02,300 --> 00:01:06,000 ..we travel to the most astonishing wild places... 13 00:01:08,200 --> 00:01:10,900 ..see mysterious creatures... 14 00:01:15,900 --> 00:01:18,900 ..witness spectacular wonders... 15 00:01:20,900 --> 00:01:24,000 ..and reveal breathtaking animal dramas. 16 00:01:38,800 --> 00:01:42,800 The natural world continues to surprise us. 17 00:01:47,200 --> 00:01:52,500 But since Darwin's time, it has changed beyond recognition... 18 00:01:53,700 --> 00:01:56,200 ..transformed by a powerful force. 19 00:01:57,200 --> 00:01:58,500 Us. 20 00:02:01,500 --> 00:02:05,500 We will see how animals are adapting in extraordinary ways 21 00:02:05,600 --> 00:02:09,000 to survive the new challenges they face. 22 00:02:11,700 --> 00:02:13,900 At this crucial time in our history, 23 00:02:14,000 --> 00:02:17,800 we must now look at the world through a new lens. 24 00:02:19,100 --> 00:02:21,900 This is Planet Earth III. 25 00:03:04,300 --> 00:03:07,700 Tasmania, Shipstern's Bluff... 26 00:03:09,200 --> 00:03:11,800 ..where two worlds collide. 27 00:03:34,500 --> 00:03:39,200 These waves have crossed more than 1,000 miles of open ocean... 28 00:03:42,000 --> 00:03:44,000 ..building in strength. 29 00:03:58,400 --> 00:04:01,900 It's here that they meet their explosive end. 30 00:04:29,200 --> 00:04:32,600 Coasts are dangerous and dynamic frontiers. 31 00:04:34,000 --> 00:04:38,100 To succeed here, life must adapt to constant change. 32 00:04:44,800 --> 00:04:47,400 South Africa's Robberg Peninsula. 33 00:04:51,500 --> 00:04:55,300 Thousands of Cape fur seals gather here to breed. 34 00:05:08,300 --> 00:05:12,200 This pup was born into a crowded world. 35 00:05:16,500 --> 00:05:21,700 But now, at nearly a year old, he can escape to the water. 36 00:05:29,000 --> 00:05:31,200 He just has to get there. 37 00:06:02,800 --> 00:06:07,300 There is no question as to where this pup belongs. 38 00:06:15,600 --> 00:06:19,500 In the water, he's fast and agile. 39 00:06:32,300 --> 00:06:34,500 And he needs to be. 40 00:06:38,200 --> 00:06:42,800 The rolling surf conceals life-threatening dangers. 41 00:07:14,800 --> 00:07:17,000 A great white shark. 42 00:07:34,900 --> 00:07:38,500 This young pup has had a very lucky escape. 43 00:07:57,400 --> 00:07:59,800 Here on Africa's southern coast, 44 00:07:59,800 --> 00:08:04,000 seals risk their lives every time they set out to eat. 45 00:08:10,700 --> 00:08:14,800 Powerful ocean currents attract huge shoals of fish. 46 00:08:24,000 --> 00:08:26,200 But in recent years, 47 00:08:26,200 --> 00:08:30,800 this stretch has attracted increased numbers of great whites too. 48 00:08:34,700 --> 00:08:39,500 The great whites are shrewd hunters and use whatever cover is available. 49 00:09:08,800 --> 00:09:12,600 This shark won't need to eat for another few days. 50 00:09:16,600 --> 00:09:18,800 But he's not alone. 51 00:09:22,600 --> 00:09:25,200 These usually solitary hunters 52 00:09:25,200 --> 00:09:28,600 are gathering in unprecedented numbers. 53 00:09:30,900 --> 00:09:33,000 A dozen at a time. 54 00:09:45,100 --> 00:09:47,200 The seals are nimble... 55 00:09:53,100 --> 00:09:55,200 ..but great whites are patient... 56 00:10:01,800 --> 00:10:04,100 ..and have explosive acceleration... 57 00:10:07,400 --> 00:10:11,300 ..hitting top speed with just five swipes of their tails. 58 00:10:22,800 --> 00:10:24,900 Cornered... 59 00:10:24,900 --> 00:10:27,800 ..the seals keep close to the jagged cliffs. 60 00:10:34,300 --> 00:10:36,200 They are trapped. 61 00:11:20,500 --> 00:11:23,400 But as the great whites move in for the kill... 62 00:11:25,300 --> 00:11:28,200 ..the seals do something astonishing. 63 00:11:32,200 --> 00:11:33,600 Together... 64 00:11:34,900 --> 00:11:37,000 ..they turn on their enemy. 65 00:11:49,800 --> 00:11:52,900 As more join, the mob grows... 66 00:11:54,800 --> 00:11:57,600 ..in both number and confidence. 67 00:12:10,800 --> 00:12:13,200 The tables are turning. 68 00:12:38,700 --> 00:12:40,900 By sheer force of numbers... 69 00:12:41,800 --> 00:12:45,700 ..these fur seals drive the world's most notorious predator... 70 00:12:48,100 --> 00:12:50,200 ..back out to sea. 71 00:12:57,900 --> 00:13:02,100 Here, animals are adapting to new challenges 72 00:13:02,200 --> 00:13:04,400 in a rapidly changing world. 73 00:13:13,000 --> 00:13:14,400 In the Arctic... 74 00:13:15,500 --> 00:13:18,800 ..monumental change is a regular event. 75 00:13:26,900 --> 00:13:28,500 Summer. 76 00:13:28,500 --> 00:13:30,900 Visitors are arriving en masse... 77 00:13:32,200 --> 00:13:36,300 ..attracted by the biggest seasonal transformation 78 00:13:36,300 --> 00:13:38,200 on any coast on Earth. 79 00:13:48,900 --> 00:13:53,500 Over 300 billion tonnes of ice are melting... 80 00:13:58,400 --> 00:14:01,200 ..releasing nutrient-rich water. 81 00:14:05,600 --> 00:14:08,900 Extraordinary newcomers appear from the depths. 82 00:14:20,200 --> 00:14:22,100 A sea angel. 83 00:14:24,700 --> 00:14:27,000 No bigger than your little finger. 84 00:14:36,700 --> 00:14:39,500 It's eaten little for months. 85 00:14:39,600 --> 00:14:42,800 Its empty stomach glows orange. 86 00:14:53,200 --> 00:14:55,900 And there are other hungry arrivals. 87 00:15:00,800 --> 00:15:02,800 A sea butterfly. 88 00:15:04,800 --> 00:15:07,200 A snail with wings. 89 00:15:15,900 --> 00:15:18,900 Both angel and butterfly are blind. 90 00:15:21,400 --> 00:15:27,000 But each monitors minute changes in the water as they search for a meal. 91 00:15:42,200 --> 00:15:45,000 This angel has a devilish side. 92 00:15:48,100 --> 00:15:51,300 Its mouth parts invert 93 00:15:51,300 --> 00:15:54,200 to form a deadly trap of tentacles... 94 00:16:05,400 --> 00:16:08,300 ..from which there is little chance of escape. 95 00:16:47,200 --> 00:16:51,900 With a stomach full of prey, this angel has lost its glow... 96 00:16:54,000 --> 00:16:56,000 ..but not its appetite. 97 00:17:00,700 --> 00:17:03,400 It feasts while it can. 98 00:17:10,000 --> 00:17:14,300 Both predator and prey will soon return to the depths... 99 00:17:16,000 --> 00:17:19,500 ..before the ice transforms this coast once again. 100 00:17:37,800 --> 00:17:39,300 Namibia... 101 00:17:40,300 --> 00:17:44,400 ..where desert lions roam across vast territories. 102 00:17:53,500 --> 00:17:58,000 These desert cats are on a never-ending search for food. 103 00:18:04,200 --> 00:18:07,200 And that has brought these young sisters... 104 00:18:08,600 --> 00:18:10,000 ..here. 105 00:18:19,900 --> 00:18:23,900 Africa's infamous Skeleton Coast. 106 00:18:29,300 --> 00:18:34,000 Following years of persecution, Namibia's lions are now protected... 107 00:18:35,200 --> 00:18:37,900 ..and their range is expanding again. 108 00:18:39,900 --> 00:18:44,200 These are the first to be seen on these shores for 40 years. 109 00:18:49,300 --> 00:18:52,200 By day, there is little for them here. 110 00:18:55,900 --> 00:18:58,800 But at night, it's a different story. 111 00:19:08,600 --> 00:19:11,500 Sea birds come here to roost 112 00:19:11,500 --> 00:19:13,700 in their thousands. 113 00:19:24,000 --> 00:19:28,400 These hungry sisters have never seen an opportunity like this. 114 00:19:33,000 --> 00:19:36,600 But no cats, certainly no desert cats, 115 00:19:36,600 --> 00:19:38,800 enjoy getting their paws wet. 116 00:19:52,500 --> 00:19:57,300 These roosting cormorants are sitting ducks 117 00:19:57,300 --> 00:19:59,800 for hunters with good night vision. 118 00:20:10,000 --> 00:20:11,700 In theory. 119 00:20:21,700 --> 00:20:24,800 Birds are not a big cat's usual prey, 120 00:20:24,800 --> 00:20:26,700 let alone sea birds. 121 00:20:28,400 --> 00:20:31,500 And these sisters need to get their eye in. 122 00:21:04,600 --> 00:21:07,900 Catching flying prey in the dark is not easy... 123 00:21:09,900 --> 00:21:12,600 ..but these lions have acquired the knack. 124 00:21:17,000 --> 00:21:19,600 Coasts can not only provide food... 125 00:21:32,400 --> 00:21:34,900 ..they can also be a sanctuary. 126 00:21:48,200 --> 00:21:52,300 This female southern right whale is nearing the end 127 00:21:52,300 --> 00:21:56,200 of a 5,000 mile journey across open ocean. 128 00:22:09,400 --> 00:22:11,500 She's kept a steady course... 129 00:22:13,500 --> 00:22:17,000 ..to a special place she has known all her life. 130 00:22:22,000 --> 00:22:25,300 Peninsula Valdes, Argentina. 131 00:22:48,500 --> 00:22:50,600 In these calm, shallow waters... 132 00:22:52,000 --> 00:22:54,400 ..her behaviour starts to change. 133 00:22:57,200 --> 00:23:00,300 She rolls and shifts her great body. 134 00:23:04,800 --> 00:23:07,600 Perhaps she's trying to get comfortable. 135 00:23:35,800 --> 00:23:38,000 Other females are close by. 136 00:23:41,800 --> 00:23:45,000 Some have been coming here for five decades... 137 00:23:46,600 --> 00:23:51,000 ..seeking the shelter of this bay at a key time in their lives. 138 00:24:08,300 --> 00:24:10,400 This whale is here... 139 00:24:11,600 --> 00:24:13,300 ..to give birth. 140 00:24:44,000 --> 00:24:46,600 A new life begins. 141 00:24:58,400 --> 00:25:01,500 The calf is totally dependent on its mother. 142 00:25:04,300 --> 00:25:08,600 She's producing as much as 200 litres of milk a day. 143 00:25:11,100 --> 00:25:15,800 The strength she loses, the calf gains. 144 00:25:21,800 --> 00:25:27,000 And it becomes more and more independent and playful. 145 00:25:36,800 --> 00:25:41,100 In this nursery bay, there are plenty of playmates. 146 00:25:51,400 --> 00:25:54,800 But a mother never lets her calf stray too far... 147 00:26:03,300 --> 00:26:06,800 ..and will always offer a welcome embrace. 148 00:26:20,000 --> 00:26:25,200 The family keeps in constant contact with whispered calls. 149 00:26:26,800 --> 00:26:28,900 New research has revealed 150 00:26:29,000 --> 00:26:34,100 that in shallow coastal waters, their calls not only fade quickly, 151 00:26:34,200 --> 00:26:39,200 but are also concealed by the sound of waves breaking on the shore... 152 00:26:45,200 --> 00:26:49,000 ..so they won't attract the attention of predators. 153 00:26:54,200 --> 00:26:58,200 Not so long ago, these whales faced a graver threat. 154 00:27:01,500 --> 00:27:04,200 They were hunted to near extinction. 155 00:27:07,400 --> 00:27:11,800 But 40 years ago, commercial whaling was banned. 156 00:27:15,200 --> 00:27:19,100 Today, their population is 12,000 strong... 157 00:27:20,500 --> 00:27:24,100 ..and this bay now attracts one of the largest gatherings 158 00:27:24,100 --> 00:27:26,800 of these whales anywhere on Earth. 159 00:27:48,700 --> 00:27:53,000 There are over a million miles of coastline around the world. 160 00:27:54,800 --> 00:27:59,600 Together, they constitute the most varied habitat on the planet. 161 00:28:03,500 --> 00:28:06,200 Here on Canada's west coast, 162 00:28:06,200 --> 00:28:09,800 some of the most powerful of all ocean currents 163 00:28:09,800 --> 00:28:12,700 deliver a constant supply of nutrients 164 00:28:12,800 --> 00:28:15,400 to the shores of countless islands. 165 00:28:29,600 --> 00:28:33,600 And those that live here take full advantage. 166 00:28:40,200 --> 00:28:44,800 This is the aptly-named wandering garter snake. 167 00:29:03,000 --> 00:29:05,000 He may seem out of place... 168 00:29:06,000 --> 00:29:08,100 ..but he's here to eat. 169 00:29:20,000 --> 00:29:24,200 The water here is more than ten degrees colder than the air. 170 00:29:31,100 --> 00:29:36,500 But that doesn't deter this intrepid hunter from taking the plunge. 171 00:29:42,400 --> 00:29:45,800 Under the water, there is an abundance of food... 172 00:29:47,800 --> 00:29:49,900 ..if he can catch it. 173 00:30:16,800 --> 00:30:18,900 Snakes are cold-blooded, 174 00:30:19,000 --> 00:30:22,400 so he can't stay in these chilly waters for long. 175 00:30:29,800 --> 00:30:33,200 Back in the sunshine, he warms his head, 176 00:30:33,200 --> 00:30:35,900 perhaps sharpening his senses. 177 00:30:39,000 --> 00:30:41,000 And then, with a gulp of air... 178 00:30:42,600 --> 00:30:44,600 ..he continues his hunt. 179 00:30:52,200 --> 00:30:54,200 It's thought that garter snakes 180 00:30:54,200 --> 00:30:58,200 can use their forked tongue underwater as they do in air, 181 00:30:58,200 --> 00:31:01,300 smelling in stereo... 182 00:31:01,300 --> 00:31:04,800 ..detecting prey wherever it hides. 183 00:31:20,400 --> 00:31:22,000 He's got something. 184 00:31:23,100 --> 00:31:25,100 A small fish. 185 00:31:30,200 --> 00:31:32,400 Now, he has to land it. 186 00:31:36,400 --> 00:31:38,000 Success. 187 00:31:43,200 --> 00:31:47,700 For those animals able to cross the divide between land and sea, 188 00:31:47,800 --> 00:31:50,200 there are surprising rewards. 189 00:31:56,800 --> 00:31:59,600 Raja Ampat in Indonesia. 190 00:32:03,500 --> 00:32:06,600 Here, there's a greater variety of animals 191 00:32:06,600 --> 00:32:09,200 than on any other coast on Earth. 192 00:32:15,200 --> 00:32:18,000 The corals are protected by mangroves. 193 00:32:19,400 --> 00:32:25,200 Salt tolerant trees that prop themselves on curving aerial roots. 194 00:32:38,400 --> 00:32:43,200 These fish have learned how to catch prey from high in the trees. 195 00:32:49,500 --> 00:32:53,400 Archerfish use jets of water like arrows. 196 00:32:58,000 --> 00:32:59,600 This pinpoint accuracy... 197 00:33:00,800 --> 00:33:03,500 ..requires some complex calculations. 198 00:33:05,800 --> 00:33:09,300 The hunter first estimates the range of its target... 199 00:33:12,500 --> 00:33:15,800 ..then loads with a precise amount of water. 200 00:33:18,400 --> 00:33:22,300 Aiming, they allow for the refraction and distortion 201 00:33:22,400 --> 00:33:25,100 created by the water's moving surface. 202 00:33:29,200 --> 00:33:30,600 And then... 203 00:33:31,800 --> 00:33:33,300 ..release... 204 00:33:35,800 --> 00:33:37,600 ..an arrow of water. 205 00:33:40,100 --> 00:33:44,900 They can hit prey up to two metres above them. 206 00:33:54,700 --> 00:33:57,200 But they're not born with this skill. 207 00:33:59,200 --> 00:34:01,000 They have to learn it. 208 00:34:03,100 --> 00:34:06,100 And they do that by studying others. 209 00:34:11,400 --> 00:34:15,800 This youngster is watching a master at work. 210 00:34:32,100 --> 00:34:34,900 It's time for the apprentice to have a go. 211 00:34:37,400 --> 00:34:40,700 First, he must select a target. 212 00:34:43,800 --> 00:34:45,800 This seems rather ambitious. 213 00:34:55,000 --> 00:34:56,500 Missed. 214 00:34:58,000 --> 00:35:01,000 Others watch to learn from his mistakes. 215 00:35:10,600 --> 00:35:12,000 Or... 216 00:35:14,400 --> 00:35:16,500 ..to steal his prize. 217 00:35:53,600 --> 00:35:55,600 Enough is enough. 218 00:35:57,800 --> 00:36:00,500 There is one way to beat the thieves. 219 00:36:05,400 --> 00:36:07,000 The archer himself... 220 00:36:08,700 --> 00:36:10,400 ..becomes the arrow. 221 00:36:31,700 --> 00:36:35,900 Mangroves are unusually stable coastal environments, 222 00:36:36,000 --> 00:36:39,900 where an archerfish can focus on beating the competition. 223 00:36:59,900 --> 00:37:03,900 But on the exposed coast of Mexico's Yucatan, 224 00:37:03,900 --> 00:37:06,000 life is precarious. 225 00:37:08,600 --> 00:37:11,700 Concentrated by the tropical sunshine, 226 00:37:11,800 --> 00:37:16,900 the brine in these shallow lagoons cannot be tolerated by most animals. 227 00:37:21,400 --> 00:37:25,000 And yet, these Caribbean flamingos 228 00:37:25,000 --> 00:37:28,400 have flown hundreds of miles to gather here. 229 00:38:04,400 --> 00:38:08,700 These hypersaline waters keep many predators at bay... 230 00:38:12,000 --> 00:38:14,600 ..so it's here they choose to nest. 231 00:38:17,800 --> 00:38:20,900 There are more than 10,000 pairs here. 232 00:38:21,000 --> 00:38:24,400 It's the largest breeding colony in North America. 233 00:38:38,300 --> 00:38:41,600 Nest mounds keep chicks clear of the brine 234 00:38:41,600 --> 00:38:44,200 while they are still at their most vulnerable. 235 00:39:20,900 --> 00:39:23,700 But this generation faces a problem. 236 00:39:32,100 --> 00:39:37,000 The storms that come each season are arriving earlier every year. 237 00:39:41,200 --> 00:39:44,600 And the colony lies directly in their path. 238 00:39:54,900 --> 00:39:58,500 Rising winds create a storm surge 239 00:39:58,500 --> 00:40:02,200 that overwhelms the most exposed nests. 240 00:40:25,200 --> 00:40:26,700 And then... 241 00:40:27,800 --> 00:40:29,300 ..it rains. 242 00:40:37,400 --> 00:40:41,500 The adults do what they can, bailing out their nests. 243 00:40:48,800 --> 00:40:51,000 But they can only do so much. 244 00:41:07,800 --> 00:41:12,800 The storm passes, but leaves devastation in its wake. 245 00:41:17,600 --> 00:41:20,000 Most nests are submerged. 246 00:41:36,400 --> 00:41:39,200 The chicks are soaked and cold... 247 00:41:40,900 --> 00:41:42,600 ..and will soon perish... 248 00:41:43,800 --> 00:41:46,200 ..unless they can get out of the water. 249 00:42:00,300 --> 00:42:03,000 The adults are unable to help. 250 00:42:07,600 --> 00:42:10,000 A chick must save itself. 251 00:42:36,500 --> 00:42:41,100 Some years, no chicks survive in this colony. 252 00:42:44,900 --> 00:42:47,600 Our coasts are vulnerable places. 253 00:42:49,400 --> 00:42:54,900 Increasingly so, as rising global temperatures create bigger storms. 254 00:42:59,000 --> 00:43:02,200 The biggest are hurricanes. 255 00:43:06,200 --> 00:43:10,900 They form over warm tropical water, building in strength at sea. 256 00:43:14,800 --> 00:43:19,000 But their full force is unleashed on our coasts... 257 00:43:21,800 --> 00:43:26,800 ..where 40% of the world's human population have made their homes. 258 00:43:40,200 --> 00:43:42,100 In this changing world... 259 00:43:43,800 --> 00:43:46,200 ..coasts are on the front line. 260 00:44:02,800 --> 00:44:04,400 Raine Island. 261 00:44:05,600 --> 00:44:08,700 One of the planet's most important breeding sites 262 00:44:08,700 --> 00:44:11,900 for one particularly precious species. 263 00:44:25,500 --> 00:44:27,200 The green turtle. 264 00:44:31,800 --> 00:44:34,300 On a few special nights each year, 265 00:44:34,400 --> 00:44:38,600 as many as 20,000 females come ashore here. 266 00:44:41,400 --> 00:44:43,700 Their instinct to nest is strong... 267 00:44:46,100 --> 00:44:51,900 ..and many haul themselves far inland in search of nesting space. 268 00:44:54,600 --> 00:45:00,200 In a single night, they may lay as many as two million eggs. 269 00:45:12,900 --> 00:45:14,400 Dawn. 270 00:45:17,400 --> 00:45:20,500 This exhausted female has nested, 271 00:45:20,500 --> 00:45:23,800 but now she faces a long return journey 272 00:45:23,800 --> 00:45:26,100 through the dunes to the sea. 273 00:45:39,300 --> 00:45:41,100 As the sun rises... 274 00:45:43,400 --> 00:45:46,700 ..she's at risk of being baked alive. 275 00:45:54,600 --> 00:45:58,500 Every inch she travels is gruelling. 276 00:46:06,800 --> 00:46:11,000 And the ebbing tide has exposed a rocky reef. 277 00:46:15,900 --> 00:46:18,800 It has already claimed many lives. 278 00:46:23,800 --> 00:46:28,100 Other females overcome by heat and exhaustion. 279 00:46:38,000 --> 00:46:39,800 Her temperature is rising. 280 00:46:40,800 --> 00:46:42,800 She has to keep going. 281 00:47:07,800 --> 00:47:13,600 As many as 2,000 female turtles may die here each year. 282 00:47:35,500 --> 00:47:38,100 But the coast is always changing. 283 00:47:47,900 --> 00:47:50,800 And the turning tide 284 00:47:50,800 --> 00:47:52,700 may yet save her. 285 00:48:21,400 --> 00:48:26,400 Half of all the green turtles in the Pacific come here to nest, 286 00:48:26,400 --> 00:48:30,100 as they have done for at least 1,000 years. 287 00:48:39,000 --> 00:48:41,200 But for how much longer? 288 00:48:47,100 --> 00:48:52,100 If sea levels rise as predicted, within the next 30 years, 289 00:48:52,100 --> 00:48:56,500 Raine Island will disappear beneath the waves. 290 00:49:04,400 --> 00:49:08,200 Coasts are dynamic, dangerous frontiers... 291 00:49:10,400 --> 00:49:14,800 ..and they are changing faster than ever before in human history. 292 00:49:18,400 --> 00:49:21,000 Life is remarkably resilient... 293 00:49:22,400 --> 00:49:24,900 ..and adapts to new challenges. 294 00:49:27,700 --> 00:49:32,200 But there is a limit on how fast it can do so. 295 00:49:53,500 --> 00:49:55,200 As far as I know, 296 00:49:55,200 --> 00:50:00,200 I was one of the first people to film on Raine Island, back in 1957. 297 00:50:02,900 --> 00:50:05,100 After a fortnight of travelling north, 298 00:50:05,200 --> 00:50:07,400 we at last sighted Raine Island. 299 00:50:08,700 --> 00:50:13,800 From the sea, it looked no more than a low sandbank covered in scrub. 300 00:50:13,800 --> 00:50:16,400 But as we rowed ashore, 301 00:50:16,400 --> 00:50:20,500 we were deafened by the cries of thousands of sea birds 302 00:50:20,500 --> 00:50:23,400 which hung above the island like a black cloud. 303 00:50:26,800 --> 00:50:31,600 I was 31 and it was here that I first met a green turtle. 304 00:50:33,200 --> 00:50:35,700 The turtles come up to lay at night, 305 00:50:35,800 --> 00:50:39,800 and after a night spent laying maybe over 100 eggs, 306 00:50:39,800 --> 00:50:44,000 she's very weary and very anxious to get back to the sea. 307 00:50:47,400 --> 00:50:49,400 Nearly 70 years later, 308 00:50:49,400 --> 00:50:52,700 the Planet Earth III team are welcomed by people 309 00:50:52,700 --> 00:50:56,900 whose connection to the island goes back very much further than mine. 310 00:50:56,900 --> 00:50:58,700 Welcome to Raine! 311 00:50:58,700 --> 00:51:00,700 The Wuthathi and Meriam people 312 00:51:00,800 --> 00:51:03,700 have been coming here for several thousand years. 313 00:51:05,400 --> 00:51:07,800 Raine Island's a beautiful and special place. 314 00:51:07,800 --> 00:51:10,300 Like, there's nowhere else on the planet 315 00:51:10,300 --> 00:51:12,800 where you come and see this much turtles. 316 00:51:12,800 --> 00:51:14,600 It's a wonder to see. 317 00:51:18,300 --> 00:51:21,500 Since I was there, it's been discovered that Raine Island 318 00:51:21,600 --> 00:51:25,700 attracts more nesting green turtles than anywhere else on the planet. 319 00:51:31,900 --> 00:51:33,500 There's so many, isn't there? 320 00:51:33,600 --> 00:51:36,400 As soon as you're up, you're like, "Oh, there are a lot." 321 00:51:36,400 --> 00:51:39,300 And the crew soon meet some other residents too. 322 00:51:40,600 --> 00:51:42,600 This is behind the behind the scenes! 323 00:51:47,500 --> 00:51:48,800 See you, mate! 324 00:51:52,400 --> 00:51:54,300 The team are here to record 325 00:51:54,300 --> 00:51:57,400 the mother turtles' perilous journeys back to the sea. 326 00:51:59,400 --> 00:52:01,200 Oh, God. 327 00:52:03,500 --> 00:52:06,100 Trapped turtles can often free themselves 328 00:52:06,100 --> 00:52:08,300 with the help of the rising tide. 329 00:52:09,600 --> 00:52:12,800 Nearly. Just a bit more to the right there. Yeah, there. 330 00:52:12,800 --> 00:52:16,900 But in this case, Keron makes the decision to intervene. 331 00:52:18,100 --> 00:52:20,900 Ready? One, two, three. 332 00:52:20,900 --> 00:52:23,500 Yeah, any time we're here we'll walk the beach. 333 00:52:23,500 --> 00:52:27,100 Any turtles that have no chance of making it back to the ocean, 334 00:52:27,200 --> 00:52:32,300 if we can save them, we save them, because every turtle is precious. 335 00:52:32,300 --> 00:52:34,400 At the time of my first visit, 336 00:52:34,400 --> 00:52:37,700 little was known to outsiders about Raine Island. 337 00:52:37,800 --> 00:52:39,900 But for the last few decades, 338 00:52:39,900 --> 00:52:43,900 scientists have been working with the Wuthathi and Meriam people 339 00:52:44,000 --> 00:52:47,000 to understand more about this special place. 340 00:52:47,900 --> 00:52:51,200 Scientists have been coming to Raine Island since about the mid '70s 341 00:52:51,200 --> 00:52:53,800 and over that time they've been monitoring 342 00:52:53,800 --> 00:52:55,700 the nesting population here. 343 00:52:57,300 --> 00:52:59,300 This work involves long hours... 344 00:53:01,300 --> 00:53:03,200 98.7. 345 00:53:03,200 --> 00:53:05,700 ..and a certain degree of patience. 346 00:53:07,800 --> 00:53:09,400 Oh! 347 00:53:14,400 --> 00:53:18,000 We're going to be wearing half of Raine Island by the end of tonight! 348 00:53:20,700 --> 00:53:24,200 Helping the year's first hatchlings is a little easier. 349 00:53:25,600 --> 00:53:27,500 So we'll take these ones down to the water's edge 350 00:53:27,500 --> 00:53:29,800 and so hopefully we'll see these turtles back here, 351 00:53:29,800 --> 00:53:31,400 laying eggs in 30 years' time. 352 00:53:32,700 --> 00:53:35,300 With the help of this dedicated team, 353 00:53:35,300 --> 00:53:39,000 Raine Island's turtles might seem to have a good future. 354 00:53:43,900 --> 00:53:47,000 But research is revealing a hidden threat. 355 00:53:51,700 --> 00:53:54,400 The direct effects of climate change. 356 00:53:58,600 --> 00:54:02,200 Do you want to hold this against the flat part of the data-logger? 357 00:54:02,200 --> 00:54:04,300 A developing turtle's sex 358 00:54:04,300 --> 00:54:07,300 is determined by the temperature of its nest. 359 00:54:08,700 --> 00:54:12,200 Higher temperatures produce female hatchlings. 360 00:54:14,100 --> 00:54:18,600 The temperature of the sand on Raine Island is now at a record high. 361 00:54:19,900 --> 00:54:24,600 So 99% of the turtles that hatch here are female. 362 00:54:26,000 --> 00:54:29,300 More alarmingly, we now know this has been case 363 00:54:29,400 --> 00:54:31,800 for at least the last 20 years. 364 00:54:33,000 --> 00:54:34,600 You do the maths. 365 00:54:34,600 --> 00:54:38,900 All females, no males. What's going to happen? 366 00:54:39,000 --> 00:54:41,200 There's going to be a population crash 367 00:54:41,200 --> 00:54:42,800 and there'll be no more turtle. 368 00:54:46,300 --> 00:54:49,500 Work is under way to find solutions. 369 00:54:49,500 --> 00:54:51,600 But that's not their only problem. 370 00:54:53,200 --> 00:54:57,700 Not only are temperatures rising, sea levels are too. 371 00:54:59,300 --> 00:55:01,900 Increasingly, high tides on Raine 372 00:55:01,900 --> 00:55:05,000 are flooding many of the nests from below... 373 00:55:07,200 --> 00:55:10,800 ..drowning the developing turtles before they hatch. 374 00:55:12,600 --> 00:55:14,000 It's really upsetting. 375 00:55:14,000 --> 00:55:17,100 You'll dig down to check to see success, 376 00:55:17,100 --> 00:55:19,300 and you get down to the nests 377 00:55:19,400 --> 00:55:21,600 and you're just pulling up dead eggs. 378 00:55:23,300 --> 00:55:27,900 To try to stop this happening, they have devised a heavy-duty solution. 379 00:55:32,600 --> 00:55:35,800 These machines have been shipped hundreds of miles 380 00:55:35,800 --> 00:55:39,400 from the Australian mainland to re-shape the beach. 381 00:55:42,200 --> 00:55:44,500 They have already shifted sand 382 00:55:44,500 --> 00:55:47,900 that would fill 16 Olympic-sized swimming pools 383 00:55:47,900 --> 00:55:50,900 and doubled the number of safe nesting sites. 384 00:55:53,400 --> 00:55:57,900 The hope is that this will ensure that over five million more eggs 385 00:55:57,900 --> 00:55:59,900 will hatch in the next decade. 386 00:56:03,200 --> 00:56:08,500 But from then on, the future of Raine Island looks very uncertain. 387 00:56:09,800 --> 00:56:13,000 At this stage, we think that we have to about 2050 388 00:56:13,000 --> 00:56:16,000 until we start seeing massive impacts of sea level rise. 389 00:56:17,000 --> 00:56:21,400 It's crazy to think that, you know, the work that we do here, 390 00:56:21,400 --> 00:56:23,500 someone might not be doing this in 30 years' time 391 00:56:23,600 --> 00:56:25,200 cos there's no island to do it on. 392 00:56:28,900 --> 00:56:34,200 What sort of world is it going to be for my children and their children? 393 00:56:34,200 --> 00:56:36,100 Is there going to be anything for... 394 00:56:37,400 --> 00:56:39,100 ..for them? Or is it... 395 00:56:40,600 --> 00:56:42,000 ..all in vain? 396 00:56:47,200 --> 00:56:50,900 We'll always be here fighting for Raine Island, for the turtles. 397 00:56:50,900 --> 00:56:54,700 But we can't do it alone and we need government and big business 398 00:56:54,700 --> 00:56:58,700 to wake up and see what they're doing to the planet and get real. 399 00:57:05,000 --> 00:57:08,100 This little fellow is newly hatched from an egg 400 00:57:08,200 --> 00:57:10,400 which had been laid a month or so earlier 401 00:57:10,400 --> 00:57:13,400 and he too is very anxious to get down to the sea. 402 00:57:17,600 --> 00:57:20,300 Having at last successfully reached the water, 403 00:57:20,300 --> 00:57:24,100 he's still got a great number of hazards to face before he grows up. 404 00:57:26,500 --> 00:57:28,300 Little did I know then 405 00:57:28,300 --> 00:57:31,300 what hazards that little turtle would have to face 406 00:57:31,400 --> 00:57:34,900 or the extraordinary lengths to which people would go 407 00:57:34,900 --> 00:57:37,200 to protect it and its island. 408 00:57:38,800 --> 00:57:43,900 In the 66 years since my visit, Raine Island has remained 409 00:57:44,000 --> 00:57:47,400 the most important green turtle nesting site on the planet. 410 00:57:48,400 --> 00:57:52,200 The question is, can it last another lifetime? 411 00:57:57,200 --> 00:57:58,600 Next time... 412 00:58:00,000 --> 00:58:02,800 ..an extraordinary journey through the ocean. 413 00:58:05,000 --> 00:58:08,200 The last unexplored frontier on our planet... 414 00:58:12,200 --> 00:58:13,800 ..where life has evolved... 415 00:58:15,200 --> 00:58:17,600 ..in the most surprising ways. 416 00:58:22,900 --> 00:58:26,500 Habitat Explorer brings animals and their habitats to life. 417 00:58:26,600 --> 00:58:30,200 Explore this free interactive and make origami animals. 418 00:58:30,200 --> 00:58:34,100 Go to bbc.co.uk/planetearth3 419 00:58:34,100 --> 00:58:36,500 and follow the links to the Open University. 420 00:58:36,500 --> 00:58:38,600 Or to order a free printed version, 421 00:58:38,600 --> 00:58:42,000 visit the website or call the numbers on the screen.