1 00:00:12,400 --> 00:00:14,479 Almost 200 years ago, 2 00:00:14,480 --> 00:00:18,799 whilst walking these very paths in the English countryside 3 00:00:18,800 --> 00:00:22,079 and observing the banks and meadows near his home, 4 00:00:22,080 --> 00:00:23,999 Charles Darwin developed 5 00:00:24,000 --> 00:00:26,599 his ground-breaking ideas about evolution, 6 00:00:26,600 --> 00:00:29,479 casting a new light on the natural world 7 00:00:29,480 --> 00:00:32,360 and opening our eyes to its true wonder. 8 00:00:33,680 --> 00:00:37,439 Since then, we've explored almost every part of the planet 9 00:00:37,440 --> 00:00:41,519 and seen nature in its astounding variety. 10 00:00:41,520 --> 00:00:44,360 But there's still much to discover. 11 00:00:47,320 --> 00:00:49,800 In this new series of Planet Earth... 12 00:00:51,320 --> 00:00:55,080 ..we travel to the most astonishing wild places... 13 00:00:57,280 --> 00:00:59,960 ..see mysterious creatures... 14 00:01:04,920 --> 00:01:07,920 ..witness spectacular wonders... 15 00:01:09,920 --> 00:01:13,000 ..and reveal breathtaking animal dramas. 16 00:01:27,800 --> 00:01:31,840 The natural world continues to surprise us. 17 00:01:36,200 --> 00:01:41,520 But since Darwin's time, it has changed beyond recognition... 18 00:01:42,720 --> 00:01:45,280 ..transformed by a powerful force. 19 00:01:46,240 --> 00:01:47,560 Us. 20 00:01:50,560 --> 00:01:54,599 We will see how animals are adapting in extraordinary ways 21 00:01:54,600 --> 00:01:58,040 to survive the new challenges they face. 22 00:02:00,760 --> 00:02:02,999 At this crucial time in our history, 23 00:02:03,000 --> 00:02:06,880 we must now look at the world through a new lens. 24 00:02:08,160 --> 00:02:10,920 This is Planet Earth III. 25 00:02:53,360 --> 00:02:56,720 Tasmania, Shipstern's Bluff... 26 00:02:58,280 --> 00:03:00,800 ..where two worlds collide. 27 00:03:23,560 --> 00:03:28,200 These waves have crossed more than 1,000 miles of open ocean... 28 00:03:31,000 --> 00:03:33,040 ..building in strength. 29 00:03:47,480 --> 00:03:50,960 It's here that they meet their explosive end. 30 00:04:18,240 --> 00:04:21,680 Coasts are dangerous and dynamic frontiers. 31 00:04:23,000 --> 00:04:27,160 To succeed here, life must adapt to constant change. 32 00:04:33,800 --> 00:04:36,480 South Africa's Robberg Peninsula. 33 00:04:40,520 --> 00:04:44,360 Thousands of Cape fur seals gather here to breed. 34 00:04:57,320 --> 00:05:01,280 This pup was born into a crowded world. 35 00:05:05,560 --> 00:05:10,760 But now, at nearly a year old, he can escape to the water. 36 00:05:18,080 --> 00:05:20,280 He just has to get there. 37 00:05:51,800 --> 00:05:56,360 There is no question as to where this pup belongs. 38 00:06:04,640 --> 00:06:08,560 In the water, he's fast and agile. 39 00:06:21,320 --> 00:06:23,560 And he needs to be. 40 00:06:27,240 --> 00:06:31,800 The rolling surf conceals life-threatening dangers. 41 00:07:03,800 --> 00:07:06,000 A great white shark. 42 00:07:23,960 --> 00:07:27,560 This young pup has had a very lucky escape. 43 00:07:46,480 --> 00:07:48,879 Here on Africa's southern coast, 44 00:07:48,880 --> 00:07:53,000 seals risk their lives every time they set out to eat. 45 00:07:59,760 --> 00:08:03,800 Powerful ocean currents attract huge shoals of fish. 46 00:08:13,040 --> 00:08:15,239 But in recent years, 47 00:08:15,240 --> 00:08:19,880 this stretch has attracted increased numbers of great whites too. 48 00:08:23,760 --> 00:08:28,520 The great whites are shrewd hunters and use whatever cover is available. 49 00:08:57,840 --> 00:09:01,680 This shark won't need to eat for another few days. 50 00:09:05,640 --> 00:09:07,800 But he's not alone. 51 00:09:11,640 --> 00:09:14,239 These usually solitary hunters 52 00:09:14,240 --> 00:09:17,640 are gathering in unprecedented numbers. 53 00:09:19,960 --> 00:09:22,000 A dozen at a time. 54 00:09:34,160 --> 00:09:36,200 The seals are nimble... 55 00:09:42,120 --> 00:09:44,280 ..but great whites are patient... 56 00:09:50,840 --> 00:09:53,120 ..and have explosive acceleration... 57 00:09:56,400 --> 00:10:00,360 ..hitting top speed with just five swipes of their tails. 58 00:10:11,880 --> 00:10:13,919 Cornered... 59 00:10:13,920 --> 00:10:16,880 ..the seals keep close to the jagged cliffs. 60 00:10:23,360 --> 00:10:25,280 They are trapped. 61 00:11:09,520 --> 00:11:12,400 But as the great whites move in for the kill... 62 00:11:14,360 --> 00:11:17,240 ..the seals do something astonishing. 63 00:11:21,200 --> 00:11:22,640 Together... 64 00:11:23,920 --> 00:11:26,080 ..they turn on their enemy. 65 00:11:38,840 --> 00:11:41,920 As more join, the mob grows... 66 00:11:43,800 --> 00:11:46,640 ..in both number and confidence. 67 00:11:59,880 --> 00:12:02,200 The tables are turning. 68 00:12:27,760 --> 00:12:29,920 By sheer force of numbers... 69 00:12:30,880 --> 00:12:34,760 ..these fur seals drive the world's most notorious predator... 70 00:12:37,160 --> 00:12:39,280 ..back out to sea. 71 00:12:46,960 --> 00:12:51,199 Here, animals are adapting to new challenges 72 00:12:51,200 --> 00:12:53,440 in a rapidly changing world. 73 00:13:02,000 --> 00:13:03,440 In the Arctic... 74 00:13:04,520 --> 00:13:07,800 ..monumental change is a regular event. 75 00:13:15,920 --> 00:13:17,559 Summer. 76 00:13:17,560 --> 00:13:19,960 Visitors are arriving en masse... 77 00:13:21,240 --> 00:13:25,359 ..attracted by the biggest seasonal transformation 78 00:13:25,360 --> 00:13:27,240 on any coast on Earth. 79 00:13:37,960 --> 00:13:42,520 Over 300 billion tonnes of ice are melting... 80 00:13:47,440 --> 00:13:50,240 ..releasing nutrient-rich water. 81 00:13:54,640 --> 00:13:57,960 Extraordinary newcomers appear from the depths. 82 00:14:09,240 --> 00:14:11,160 A sea angel. 83 00:14:13,720 --> 00:14:16,080 No bigger than your little finger. 84 00:14:25,760 --> 00:14:28,599 It's eaten little for months. 85 00:14:28,600 --> 00:14:31,800 Its empty stomach glows orange. 86 00:14:42,280 --> 00:14:44,960 And there are other hungry arrivals. 87 00:14:49,880 --> 00:14:51,800 A sea butterfly. 88 00:14:53,840 --> 00:14:56,280 A snail with wings. 89 00:15:04,920 --> 00:15:07,960 Both angel and butterfly are blind. 90 00:15:10,400 --> 00:15:16,080 But each monitors minute changes in the water as they search for a meal. 91 00:15:31,240 --> 00:15:34,040 This angel has a devilish side. 92 00:15:37,120 --> 00:15:40,359 Its mouth parts invert 93 00:15:40,360 --> 00:15:43,280 to form a deadly trap of tentacles... 94 00:15:54,400 --> 00:15:57,360 ..from which there is little chance of escape. 95 00:16:36,200 --> 00:16:40,920 With a stomach full of prey, this angel has lost its glow... 96 00:16:43,040 --> 00:16:45,080 ..but not its appetite. 97 00:16:49,720 --> 00:16:52,440 It feasts while it can. 98 00:16:59,080 --> 00:17:03,320 Both predator and prey will soon return to the depths... 99 00:17:05,080 --> 00:17:08,560 ..before the ice transforms this coast once again. 100 00:17:26,840 --> 00:17:28,320 Namibia... 101 00:17:29,320 --> 00:17:33,480 ..where desert lions roam across vast territories. 102 00:17:42,520 --> 00:17:47,040 These desert cats are on a never-ending search for food. 103 00:17:53,240 --> 00:17:56,200 And that has brought these young sisters... 104 00:17:57,600 --> 00:17:59,040 ..here. 105 00:18:08,920 --> 00:18:12,960 Africa's infamous Skeleton Coast. 106 00:18:18,360 --> 00:18:23,000 Following years of persecution, Namibia's lions are now protected... 107 00:18:24,200 --> 00:18:26,920 ..and their range is expanding again. 108 00:18:28,920 --> 00:18:33,280 These are the first to be seen on these shores for 40 years. 109 00:18:38,320 --> 00:18:41,280 By day, there is little for them here. 110 00:18:44,960 --> 00:18:47,840 But at night, it's a different story. 111 00:18:57,600 --> 00:19:00,519 Sea birds come here to roost 112 00:19:00,520 --> 00:19:02,720 in their thousands. 113 00:19:13,080 --> 00:19:17,400 These hungry sisters have never seen an opportunity like this. 114 00:19:22,040 --> 00:19:25,639 But no cats, certainly no desert cats, 115 00:19:25,640 --> 00:19:27,840 enjoy getting their paws wet. 116 00:19:41,560 --> 00:19:46,319 These roosting cormorants are sitting ducks 117 00:19:46,320 --> 00:19:48,800 for hunters with good night vision. 118 00:19:59,000 --> 00:20:00,760 In theory. 119 00:20:10,720 --> 00:20:13,839 Birds are not a big cat's usual prey, 120 00:20:13,840 --> 00:20:15,760 let alone sea birds. 121 00:20:17,480 --> 00:20:20,520 And these sisters need to get their eye in. 122 00:20:53,600 --> 00:20:56,920 Catching flying prey in the dark is not easy... 123 00:20:58,920 --> 00:21:01,640 ..but these lions have acquired the knack. 124 00:21:06,000 --> 00:21:08,640 Coasts can not only provide food... 125 00:21:21,440 --> 00:21:23,960 ..they can also be a sanctuary. 126 00:21:37,280 --> 00:21:41,319 This female southern right whale is nearing the end 127 00:21:41,320 --> 00:21:45,280 of a 5,000 mile journey across open ocean. 128 00:21:58,440 --> 00:22:00,560 She's kept a steady course... 129 00:22:02,560 --> 00:22:06,080 ..to a special place she has known all her life. 130 00:22:11,000 --> 00:22:14,360 Peninsula Valdes, Argentina. 131 00:22:37,520 --> 00:22:39,680 In these calm, shallow waters... 132 00:22:41,000 --> 00:22:43,440 ..her behaviour starts to change. 133 00:22:46,200 --> 00:22:49,320 She rolls and shifts her great body. 134 00:22:53,840 --> 00:22:56,680 Perhaps she's trying to get comfortable. 135 00:23:24,840 --> 00:23:27,080 Other females are close by. 136 00:23:30,800 --> 00:23:34,000 Some have been coming here for five decades... 137 00:23:35,600 --> 00:23:40,000 ..seeking the shelter of this bay at a key time in their lives. 138 00:23:57,360 --> 00:23:59,440 This whale is here... 139 00:24:00,600 --> 00:24:02,360 ..to give birth. 140 00:24:33,080 --> 00:24:35,600 A new life begins. 141 00:24:47,400 --> 00:24:50,560 The calf is totally dependent on its mother. 142 00:24:53,320 --> 00:24:57,640 She's producing as much as 200 litres of milk a day. 143 00:25:00,120 --> 00:25:04,800 The strength she loses, the calf gains. 144 00:25:10,880 --> 00:25:16,000 And it becomes more and more independent and playful. 145 00:25:25,840 --> 00:25:30,160 In this nursery bay, there are plenty of playmates. 146 00:25:40,480 --> 00:25:43,880 But a mother never lets her calf stray too far... 147 00:25:52,320 --> 00:25:55,880 ..and will always offer a welcome embrace. 148 00:26:09,000 --> 00:26:14,280 The family keeps in constant contact with whispered calls. 149 00:26:15,800 --> 00:26:17,999 New research has revealed 150 00:26:18,000 --> 00:26:23,199 that in shallow coastal waters, their calls not only fade quickly, 151 00:26:23,200 --> 00:26:28,200 but are also concealed by the sound of waves breaking on the shore... 152 00:26:34,200 --> 00:26:38,000 ..so they won't attract the attention of predators. 153 00:26:43,200 --> 00:26:47,240 Not so long ago, these whales faced a graver threat. 154 00:26:50,560 --> 00:26:53,200 They were hunted to near extinction. 155 00:26:56,480 --> 00:27:00,880 But 40 years ago, commercial whaling was banned. 156 00:27:04,200 --> 00:27:08,160 Today, their population is 12,000 strong... 157 00:27:09,520 --> 00:27:13,119 ..and this bay now attracts one of the largest gatherings 158 00:27:13,120 --> 00:27:15,880 of these whales anywhere on Earth. 159 00:27:37,760 --> 00:27:42,000 There are over a million miles of coastline around the world. 160 00:27:43,840 --> 00:27:48,600 Together, they constitute the most varied habitat on the planet. 161 00:27:52,560 --> 00:27:55,279 Here on Canada's west coast, 162 00:27:55,280 --> 00:27:58,879 some of the most powerful of all ocean currents 163 00:27:58,880 --> 00:28:01,799 deliver a constant supply of nutrients 164 00:28:01,800 --> 00:28:04,480 to the shores of countless islands. 165 00:28:18,640 --> 00:28:22,680 And those that live here take full advantage. 166 00:28:29,200 --> 00:28:33,880 This is the aptly-named wandering garter snake. 167 00:28:52,000 --> 00:28:54,040 He may seem out of place... 168 00:28:55,000 --> 00:28:57,160 ..but he's here to eat. 169 00:29:09,000 --> 00:29:13,240 The water here is more than ten degrees colder than the air. 170 00:29:20,120 --> 00:29:25,520 But that doesn't deter this intrepid hunter from taking the plunge. 171 00:29:31,400 --> 00:29:34,840 Under the water, there is an abundance of food... 172 00:29:36,880 --> 00:29:38,920 ..if he can catch it. 173 00:30:05,800 --> 00:30:07,999 Snakes are cold-blooded, 174 00:30:08,000 --> 00:30:11,440 so he can't stay in these chilly waters for long. 175 00:30:18,840 --> 00:30:22,239 Back in the sunshine, he warms his head, 176 00:30:22,240 --> 00:30:24,920 perhaps sharpening his senses. 177 00:30:28,000 --> 00:30:30,040 And then, with a gulp of air... 178 00:30:31,640 --> 00:30:33,680 ..he continues his hunt. 179 00:30:41,200 --> 00:30:43,239 It's thought that garter snakes 180 00:30:43,240 --> 00:30:47,279 can use their forked tongue underwater as they do in air, 181 00:30:47,280 --> 00:30:50,359 smelling in stereo... 182 00:30:50,360 --> 00:30:53,800 ..detecting prey wherever it hides. 183 00:31:09,400 --> 00:31:11,000 He's got something. 184 00:31:12,160 --> 00:31:14,160 A small fish. 185 00:31:19,280 --> 00:31:21,400 Now, he has to land it. 186 00:31:25,400 --> 00:31:27,040 Success. 187 00:31:32,200 --> 00:31:36,799 For those animals able to cross the divide between land and sea, 188 00:31:36,800 --> 00:31:39,280 there are surprising rewards. 189 00:31:45,880 --> 00:31:48,680 Raja Ampat in Indonesia. 190 00:31:52,560 --> 00:31:55,639 Here, there's a greater variety of animals 191 00:31:55,640 --> 00:31:58,240 than on any other coast on Earth. 192 00:32:04,240 --> 00:32:07,080 The corals are protected by mangroves. 193 00:32:08,440 --> 00:32:14,240 Salt tolerant trees that prop themselves on curving aerial roots. 194 00:32:27,400 --> 00:32:32,240 These fish have learned how to catch prey from high in the trees. 195 00:32:38,560 --> 00:32:42,400 Archerfish use jets of water like arrows. 196 00:32:47,000 --> 00:32:48,680 This pinpoint accuracy... 197 00:32:49,880 --> 00:32:52,520 ..requires some complex calculations. 198 00:32:54,880 --> 00:32:58,360 The hunter first estimates the range of its target... 199 00:33:01,520 --> 00:33:04,880 ..then loads with a precise amount of water. 200 00:33:07,400 --> 00:33:11,399 Aiming, they allow for the refraction and distortion 201 00:33:11,400 --> 00:33:14,120 created by the water's moving surface. 202 00:33:18,240 --> 00:33:19,600 And then... 203 00:33:20,800 --> 00:33:22,320 ..release... 204 00:33:24,800 --> 00:33:26,680 ..an arrow of water. 205 00:33:29,160 --> 00:33:33,960 They can hit prey up to two metres above them. 206 00:33:43,760 --> 00:33:46,280 But they're not born with this skill. 207 00:33:48,200 --> 00:33:50,080 They have to learn it. 208 00:33:52,120 --> 00:33:55,160 And they do that by studying others. 209 00:34:00,440 --> 00:34:04,840 This youngster is watching a master at work. 210 00:34:21,120 --> 00:34:23,920 It's time for the apprentice to have a go. 211 00:34:26,440 --> 00:34:29,760 First, he must select a target. 212 00:34:32,800 --> 00:34:34,880 This seems rather ambitious. 213 00:34:44,000 --> 00:34:45,520 Missed. 214 00:34:47,040 --> 00:34:50,000 Others watch to learn from his mistakes. 215 00:34:59,640 --> 00:35:01,000 Or... 216 00:35:03,400 --> 00:35:05,560 ..to steal his prize. 217 00:35:42,600 --> 00:35:44,640 Enough is enough. 218 00:35:46,880 --> 00:35:49,560 There is one way to beat the thieves. 219 00:35:54,440 --> 00:35:56,080 The archer himself... 220 00:35:57,720 --> 00:35:59,400 ..becomes the arrow. 221 00:36:20,760 --> 00:36:24,999 Mangroves are unusually stable coastal environments, 222 00:36:25,000 --> 00:36:28,960 where an archerfish can focus on beating the competition. 223 00:36:48,920 --> 00:36:52,919 But on the exposed coast of Mexico's Yucatan, 224 00:36:52,920 --> 00:36:55,000 life is precarious. 225 00:36:57,640 --> 00:37:00,799 Concentrated by the tropical sunshine, 226 00:37:00,800 --> 00:37:05,920 the brine in these shallow lagoons cannot be tolerated by most animals. 227 00:37:10,400 --> 00:37:14,079 And yet, these Caribbean flamingos 228 00:37:14,080 --> 00:37:17,440 have flown hundreds of miles to gather here. 229 00:37:53,440 --> 00:37:57,760 These hypersaline waters keep many predators at bay... 230 00:38:01,040 --> 00:38:03,600 ..so it's here they choose to nest. 231 00:38:06,880 --> 00:38:09,999 There are more than 10,000 pairs here. 232 00:38:10,000 --> 00:38:13,400 It's the largest breeding colony in North America. 233 00:38:27,320 --> 00:38:30,639 Nest mounds keep chicks clear of the brine 234 00:38:30,640 --> 00:38:33,280 while they are still at their most vulnerable. 235 00:39:09,920 --> 00:39:12,760 But this generation faces a problem. 236 00:39:21,120 --> 00:39:26,040 The storms that come each season are arriving earlier every year. 237 00:39:30,280 --> 00:39:33,640 And the colony lies directly in their path. 238 00:39:43,960 --> 00:39:47,519 Rising winds create a storm surge 239 00:39:47,520 --> 00:39:51,280 that overwhelms the most exposed nests. 240 00:40:14,240 --> 00:40:15,760 And then... 241 00:40:16,840 --> 00:40:18,360 ..it rains. 242 00:40:26,480 --> 00:40:30,520 The adults do what they can, bailing out their nests. 243 00:40:37,800 --> 00:40:40,040 But they can only do so much. 244 00:40:56,840 --> 00:41:01,880 The storm passes, but leaves devastation in its wake. 245 00:41:06,640 --> 00:41:09,040 Most nests are submerged. 246 00:41:25,480 --> 00:41:28,240 The chicks are soaked and cold... 247 00:41:29,960 --> 00:41:31,640 ..and will soon perish... 248 00:41:32,880 --> 00:41:35,240 ..unless they can get out of the water. 249 00:41:49,360 --> 00:41:52,000 The adults are unable to help. 250 00:41:56,640 --> 00:41:59,080 A chick must save itself. 251 00:42:25,560 --> 00:42:30,160 Some years, no chicks survive in this colony. 252 00:42:33,920 --> 00:42:36,600 Our coasts are vulnerable places. 253 00:42:38,440 --> 00:42:43,920 Increasingly so, as rising global temperatures create bigger storms. 254 00:42:48,080 --> 00:42:51,280 The biggest are hurricanes. 255 00:42:55,200 --> 00:42:59,920 They form over warm tropical water, building in strength at sea. 256 00:43:03,880 --> 00:43:08,000 But their full force is unleashed on our coasts... 257 00:43:10,800 --> 00:43:15,880 ..where 40% of the world's human population have made their homes. 258 00:43:29,200 --> 00:43:31,160 In this changing world... 259 00:43:32,800 --> 00:43:35,240 ..coasts are on the front line. 260 00:43:51,800 --> 00:43:53,400 Raine Island. 261 00:43:54,640 --> 00:43:57,719 One of the planet's most important breeding sites 262 00:43:57,720 --> 00:44:00,960 for one particularly precious species. 263 00:44:14,520 --> 00:44:16,240 The green turtle. 264 00:44:20,800 --> 00:44:23,399 On a few special nights each year, 265 00:44:23,400 --> 00:44:27,640 as many as 20,000 females come ashore here. 266 00:44:30,440 --> 00:44:32,720 Their instinct to nest is strong... 267 00:44:35,160 --> 00:44:40,920 ..and many haul themselves far inland in search of nesting space. 268 00:44:43,680 --> 00:44:49,200 In a single night, they may lay as many as two million eggs. 269 00:45:01,960 --> 00:45:03,400 Dawn. 270 00:45:06,480 --> 00:45:09,559 This exhausted female has nested, 271 00:45:09,560 --> 00:45:12,839 but now she faces a long return journey 272 00:45:12,840 --> 00:45:15,160 through the dunes to the sea. 273 00:45:28,320 --> 00:45:30,160 As the sun rises... 274 00:45:32,480 --> 00:45:35,760 ..she's at risk of being baked alive. 275 00:45:43,640 --> 00:45:47,560 Every inch she travels is gruelling. 276 00:45:55,880 --> 00:46:00,000 And the ebbing tide has exposed a rocky reef. 277 00:46:04,920 --> 00:46:07,840 It has already claimed many lives. 278 00:46:12,800 --> 00:46:17,120 Other females overcome by heat and exhaustion. 279 00:46:27,080 --> 00:46:28,840 Her temperature is rising. 280 00:46:29,800 --> 00:46:31,840 She has to keep going. 281 00:46:56,840 --> 00:47:02,680 As many as 2,000 female turtles may die here each year. 282 00:47:24,560 --> 00:47:27,120 But the coast is always changing. 283 00:47:36,960 --> 00:47:39,839 And the turning tide 284 00:47:39,840 --> 00:47:41,760 may yet save her. 285 00:48:10,480 --> 00:48:15,439 Half of all the green turtles in the Pacific come here to nest, 286 00:48:15,440 --> 00:48:19,120 as they have done for at least 1,000 years. 287 00:48:28,000 --> 00:48:30,240 But for how much longer? 288 00:48:36,160 --> 00:48:41,159 If sea levels rise as predicted, within the next 30 years, 289 00:48:41,160 --> 00:48:45,520 Raine Island will disappear beneath the waves. 290 00:48:53,400 --> 00:48:57,240 Coasts are dynamic, dangerous frontiers... 291 00:48:59,440 --> 00:49:03,880 ..and they are changing faster than ever before in human history. 292 00:49:07,480 --> 00:49:10,040 Life is remarkably resilient... 293 00:49:11,440 --> 00:49:13,960 ..and adapts to new challenges. 294 00:49:16,720 --> 00:49:21,280 But there is a limit on how fast it can do so. 295 00:49:42,520 --> 00:49:44,279 As far as I know, 296 00:49:44,280 --> 00:49:49,280 I was one of the first people to film on Raine Island, back in 1957. 297 00:49:51,920 --> 00:49:54,199 After a fortnight of travelling north, 298 00:49:54,200 --> 00:49:56,480 we at last sighted Raine Island. 299 00:49:57,760 --> 00:50:02,839 From the sea, it looked no more than a low sandbank covered in scrub. 300 00:50:02,840 --> 00:50:05,479 But as we rowed ashore, 301 00:50:05,480 --> 00:50:09,559 we were deafened by the cries of thousands of sea birds 302 00:50:09,560 --> 00:50:12,480 which hung above the island like a black cloud. 303 00:50:15,800 --> 00:50:20,680 I was 31 and it was here that I first met a green turtle. 304 00:50:22,240 --> 00:50:24,799 The turtles come up to lay at night, 305 00:50:24,800 --> 00:50:28,839 and after a night spent laying maybe over 100 eggs, 306 00:50:28,840 --> 00:50:33,000 she's very weary and very anxious to get back to the sea. 307 00:50:36,480 --> 00:50:38,439 Nearly 70 years later, 308 00:50:38,440 --> 00:50:41,719 the Planet Earth III team are welcomed by people 309 00:50:41,720 --> 00:50:45,959 whose connection to the island goes back very much further than mine. 310 00:50:45,960 --> 00:50:47,719 Welcome to Raine! 311 00:50:47,720 --> 00:50:49,799 The Wuthathi and Meriam people 312 00:50:49,800 --> 00:50:52,760 have been coming here for several thousand years. 313 00:50:54,480 --> 00:50:56,839 Raine Island's a beautiful and special place. 314 00:50:56,840 --> 00:50:59,359 Like, there's nowhere else on the planet 315 00:50:59,360 --> 00:51:01,839 where you come and see this much turtles. 316 00:51:01,840 --> 00:51:03,640 It's a wonder to see. 317 00:51:07,320 --> 00:51:10,599 Since I was there, it's been discovered that Raine Island 318 00:51:10,600 --> 00:51:14,760 attracts more nesting green turtles than anywhere else on the planet. 319 00:51:20,960 --> 00:51:22,599 There's so many, isn't there? 320 00:51:22,600 --> 00:51:25,479 As soon as you're up, you're like, "Oh, there are a lot." 321 00:51:25,480 --> 00:51:28,360 And the crew soon meet some other residents too. 322 00:51:29,600 --> 00:51:31,600 This is behind the behind the scenes! 323 00:51:36,520 --> 00:51:37,880 See you, mate! 324 00:51:41,400 --> 00:51:43,359 The team are here to record 325 00:51:43,360 --> 00:51:46,400 the mother turtles' perilous journeys back to the sea. 326 00:51:48,400 --> 00:51:50,240 Oh, God. 327 00:51:52,560 --> 00:51:55,159 Trapped turtles can often free themselves 328 00:51:55,160 --> 00:51:57,360 with the help of the rising tide. 329 00:51:58,600 --> 00:52:01,839 Nearly. Just a bit more to the right there. Yeah, there. 330 00:52:01,840 --> 00:52:05,920 But in this case, Keron makes the decision to intervene. 331 00:52:07,160 --> 00:52:09,919 Ready? One, two, three. 332 00:52:09,920 --> 00:52:12,519 Yeah, any time we're here we'll walk the beach. 333 00:52:12,520 --> 00:52:16,199 Any turtles that have no chance of making it back to the ocean, 334 00:52:16,200 --> 00:52:21,319 if we can save them, we save them, because every turtle is precious. 335 00:52:21,320 --> 00:52:23,439 At the time of my first visit, 336 00:52:23,440 --> 00:52:26,799 little was known to outsiders about Raine Island. 337 00:52:26,800 --> 00:52:28,959 But for the last few decades, 338 00:52:28,960 --> 00:52:32,999 scientists have been working with the Wuthathi and Meriam people 339 00:52:33,000 --> 00:52:36,000 to understand more about this special place. 340 00:52:36,960 --> 00:52:40,279 Scientists have been coming to Raine Island since about the mid '70s 341 00:52:40,280 --> 00:52:42,839 and over that time they've been monitoring 342 00:52:42,840 --> 00:52:44,760 the nesting population here. 343 00:52:46,320 --> 00:52:48,360 This work involves long hours... 344 00:52:50,360 --> 00:52:52,239 98.7. 345 00:52:52,240 --> 00:52:54,720 ..and a certain degree of patience. 346 00:52:56,800 --> 00:52:58,479 Oh! 347 00:53:03,480 --> 00:53:07,040 We're going to be wearing half of Raine Island by the end of tonight! 348 00:53:09,720 --> 00:53:13,200 Helping the year's first hatchlings is a little easier. 349 00:53:14,600 --> 00:53:16,559 So we'll take these ones down to the water's edge 350 00:53:16,560 --> 00:53:18,839 and so hopefully we'll see these turtles back here, 351 00:53:18,840 --> 00:53:20,480 laying eggs in 30 years' time. 352 00:53:21,760 --> 00:53:24,359 With the help of this dedicated team, 353 00:53:24,360 --> 00:53:28,040 Raine Island's turtles might seem to have a good future. 354 00:53:32,920 --> 00:53:36,040 But research is revealing a hidden threat. 355 00:53:40,720 --> 00:53:43,480 The direct effects of climate change. 356 00:53:47,680 --> 00:53:51,279 Do you want to hold this against the flat part of the data-logger? 357 00:53:51,280 --> 00:53:53,359 A developing turtle's sex 358 00:53:53,360 --> 00:53:56,320 is determined by the temperature of its nest. 359 00:53:57,720 --> 00:54:01,280 Higher temperatures produce female hatchlings. 360 00:54:03,120 --> 00:54:07,680 The temperature of the sand on Raine Island is now at a record high. 361 00:54:08,960 --> 00:54:13,600 So 99% of the turtles that hatch here are female. 362 00:54:15,040 --> 00:54:18,399 More alarmingly, we now know this has been case 363 00:54:18,400 --> 00:54:20,880 for at least the last 20 years. 364 00:54:22,000 --> 00:54:23,639 You do the maths. 365 00:54:23,640 --> 00:54:27,999 All females, no males. What's going to happen? 366 00:54:28,000 --> 00:54:30,239 There's going to be a population crash 367 00:54:30,240 --> 00:54:31,880 and there'll be no more turtle. 368 00:54:35,320 --> 00:54:38,519 Work is under way to find solutions. 369 00:54:38,520 --> 00:54:40,600 But that's not their only problem. 370 00:54:42,200 --> 00:54:46,720 Not only are temperatures rising, sea levels are too. 371 00:54:48,360 --> 00:54:50,919 Increasingly, high tides on Raine 372 00:54:50,920 --> 00:54:54,040 are flooding many of the nests from below... 373 00:54:56,240 --> 00:54:59,880 ..drowning the developing turtles before they hatch. 374 00:55:01,640 --> 00:55:03,079 It's really upsetting. 375 00:55:03,080 --> 00:55:06,119 You'll dig down to check to see success, 376 00:55:06,120 --> 00:55:08,399 and you get down to the nests 377 00:55:08,400 --> 00:55:10,680 and you're just pulling up dead eggs. 378 00:55:12,360 --> 00:55:16,960 To try to stop this happening, they have devised a heavy-duty solution. 379 00:55:21,640 --> 00:55:24,879 These machines have been shipped hundreds of miles 380 00:55:24,880 --> 00:55:28,400 from the Australian mainland to re-shape the beach. 381 00:55:31,200 --> 00:55:33,519 They have already shifted sand 382 00:55:33,520 --> 00:55:36,919 that would fill 16 Olympic-sized swimming pools 383 00:55:36,920 --> 00:55:39,960 and doubled the number of safe nesting sites. 384 00:55:42,440 --> 00:55:46,919 The hope is that this will ensure that over five million more eggs 385 00:55:46,920 --> 00:55:48,920 will hatch in the next decade. 386 00:55:52,200 --> 00:55:57,520 But from then on, the future of Raine Island looks very uncertain. 387 00:55:58,800 --> 00:56:02,039 At this stage, we think that we have to about 2050 388 00:56:02,040 --> 00:56:05,080 until we start seeing massive impacts of sea level rise. 389 00:56:06,040 --> 00:56:10,439 It's crazy to think that, you know, the work that we do here, 390 00:56:10,440 --> 00:56:12,599 someone might not be doing this in 30 years' time 391 00:56:12,600 --> 00:56:14,200 cos there's no island to do it on. 392 00:56:17,920 --> 00:56:23,279 What sort of world is it going to be for my children and their children? 393 00:56:23,280 --> 00:56:25,120 Is there going to be anything for... 394 00:56:26,480 --> 00:56:28,160 ..for them? Or is it... 395 00:56:29,600 --> 00:56:31,040 ..all in vain? 396 00:56:36,200 --> 00:56:39,919 We'll always be here fighting for Raine Island, for the turtles. 397 00:56:39,920 --> 00:56:43,759 But we can't do it alone and we need government and big business 398 00:56:43,760 --> 00:56:47,760 to wake up and see what they're doing to the planet and get real. 399 00:56:54,000 --> 00:56:57,199 This little fellow is newly hatched from an egg 400 00:56:57,200 --> 00:56:59,479 which had been laid a month or so earlier 401 00:56:59,480 --> 00:57:02,440 and he too is very anxious to get down to the sea. 402 00:57:06,640 --> 00:57:09,319 Having at last successfully reached the water, 403 00:57:09,320 --> 00:57:13,120 he's still got a great number of hazards to face before he grows up. 404 00:57:15,520 --> 00:57:17,359 Little did I know then 405 00:57:17,360 --> 00:57:20,399 what hazards that little turtle would have to face 406 00:57:20,400 --> 00:57:23,959 or the extraordinary lengths to which people would go 407 00:57:23,960 --> 00:57:26,280 to protect it and its island. 408 00:57:27,800 --> 00:57:32,999 In the 66 years since my visit, Raine Island has remained 409 00:57:33,000 --> 00:57:36,440 the most important green turtle nesting site on the planet. 410 00:57:37,400 --> 00:57:41,240 The question is, can it last another lifetime? 411 00:57:46,200 --> 00:57:47,680 Next time... 412 00:57:49,000 --> 00:57:51,880 ..an extraordinary journey through the ocean. 413 00:57:54,080 --> 00:57:57,240 The last unexplored frontier on our planet... 414 00:58:01,280 --> 00:58:02,880 ..where life has evolved... 415 00:58:04,200 --> 00:58:06,640 ..in the most surprising ways. 416 00:58:11,960 --> 00:58:15,599 Habitat Explorer brings animals and their habitats to life. 417 00:58:15,600 --> 00:58:19,279 Explore this free interactive and make origami animals. 418 00:58:19,280 --> 00:58:23,159 Go to bbc.co.uk/planetearth3 419 00:58:23,160 --> 00:58:25,519 and follow the links to the Open University. 420 00:58:25,520 --> 00:58:27,679 Or to order a free printed version, 421 00:58:27,680 --> 00:58:31,000 visit the website or call the numbers on the screen.