1
00:00:00,270 --> 00:00:05,480
Blue.Planet.II《蓝色星球2》S01E01

2
00:00:05,880 --> 00:00:10,000
Sync & Encoded by Owen Lee

3
00:00:10,576 --> 00:00:16,120
看电影学英语 看美剧学英语，请关注：

4
00:00:16,400 --> 00:00:22,000
=-www.en580.com-=『英语我帮您』

5
00:00:32,320 --> 00:00:33,913
DAVID ATTENBOROUGH: Antarctica.

6
00:00:37,720 --> 00:00:43,114
The coldest, the harshest, and the most remote continent on Earth.

7
00:00:50,000 --> 00:00:54,517
No human being has ever descended into the depths that surround it...

8
00:00:57,920 --> 00:00:59,149
...until now.

9
00:01:06,560 --> 00:01:11,271
The deep ocean is as challenging to explore as space.

10
00:01:14,240 --> 00:01:16,835
We know more about the surface of Mars

11
00:01:16,920 --> 00:01:19,833
than we do about the deepest parts of our seas.

12
00:01:43,480 --> 00:01:47,110
Now we can dive these uncharted depths,

13
00:01:47,240 --> 00:01:49,630
to discover what secrets lie beneath.

14
00:02:24,640 --> 00:02:28,793
Sinking down beside the submerged wall of an iceberg,

15
00:02:28,880 --> 00:02:31,475
we enter an unforgiving world.

16
00:02:41,760 --> 00:02:44,992
These waters are the coldest on Earth.

17
00:02:49,560 --> 00:02:51,597
As we descend into the deep,

18
00:02:51,680 --> 00:02:54,434
the pressure increases relentlessly.

19
00:03:11,880 --> 00:03:14,918
And the light from above all but disappears.

20
00:03:22,280 --> 00:03:23,794
Yet, incredibly...

21
00:03:27,920 --> 00:03:29,673
there is life here.

22
00:03:51,200 --> 00:03:52,600
We might have expected

23
00:03:52,680 --> 00:03:55,718
that deep beneath the surface of the Polar seas,

24
00:03:56,760 --> 00:03:59,594
the waters would be truly barren.

25
00:04:07,000 --> 00:04:11,836
But, in fact, we find life here in unimaginable abundance.

26
00:04:25,880 --> 00:04:30,238
Nor is such great abundance confined to Antarctic waters.

27
00:04:33,440 --> 00:04:35,557
Currents carry this richness

28
00:04:35,640 --> 00:04:39,600
into the depths of almost every ocean around the world.

29
00:04:43,640 --> 00:04:46,030
Astonishingly, in the deep sea,

30
00:04:46,120 --> 00:04:49,875
there is more life than anywhere else on Earth.

31
00:05:17,200 --> 00:05:19,237
The sunlight fades,

32
00:05:19,680 --> 00:05:21,273
and the seas darken.

33
00:05:25,080 --> 00:05:28,278
Here, in the Pacific, 200 metres down,

34
00:05:28,360 --> 00:05:31,080
we enter an alien world.

35
00:05:33,440 --> 00:05:35,750
The Twilight Zone,

36
00:05:35,840 --> 00:05:38,560
a sea of eternal gloom.

37
00:05:46,280 --> 00:05:48,476
There are strange creatures here.

38
00:05:50,040 --> 00:05:51,315
A pyrosome.

39
00:05:52,600 --> 00:05:57,436
A tube of jelly two metres long that dwarfs a visitor from above,

40
00:05:58,520 --> 00:06:00,637
an oceanic whitetip shark.

41
00:06:09,240 --> 00:06:13,314
Only a tiny amount of light filters down this far.

42
00:06:17,960 --> 00:06:22,910
Survival here means making the most of every last glimmer.

43
00:06:32,000 --> 00:06:33,229
A swordfish.

44
00:06:42,200 --> 00:06:47,480
Its eyes are as big as tennis balls to help it see in the perpetual dusk.

45
00:06:52,800 --> 00:06:56,635
A squid, but this is one that lives only here.

46
00:06:57,960 --> 00:07:01,112
Its right eye looks permanently downwards.

47
00:07:03,400 --> 00:07:06,598
But its left eye is much bigger and trained upwards

48
00:07:06,720 --> 00:07:10,680
to detect the silhouettes of prey swimming nearer the surface.

49
00:07:12,800 --> 00:07:16,032
No wonder it's nicknamed the "cock-eyed squid".

50
00:07:22,320 --> 00:07:24,312
And even stranger,

51
00:07:26,480 --> 00:07:28,711
this is barreleye,

52
00:07:31,560 --> 00:07:34,280
a fish with a transparent head,

53
00:07:35,000 --> 00:07:36,832
filled with jelly,

54
00:07:36,920 --> 00:07:39,913
so that it can look up through its skull.

55
00:07:56,920 --> 00:08:00,152
We now know that the Twilight Zone is a refuge

56
00:08:00,280 --> 00:08:05,036
for an incredible 90% of all fish in the ocean.

57
00:08:10,800 --> 00:08:14,919
Only at night, do vast shoals of lanternfish

58
00:08:15,000 --> 00:08:18,994
migrate to the surface to feed on tiny plankton.

59
00:08:29,520 --> 00:08:33,070
By day, they retreat back down here.

60
00:08:48,360 --> 00:08:50,397
Humboldt squid.

61
00:09:02,560 --> 00:09:05,598
Two metres long and 50 kilos in weight.

62
00:09:10,760 --> 00:09:14,037
Like most squid, they're voracious hunters.

63
00:09:21,960 --> 00:09:23,280
There are hundreds of them.

64
00:09:34,320 --> 00:09:36,676
They found a shoal of lanternfish

65
00:09:36,760 --> 00:09:40,549
hiding 800 metres down, off the coast of South America.

66
00:09:53,040 --> 00:09:55,794
Their tentacles are armed with powerful suckers

67
00:09:55,880 --> 00:09:57,917
with which they grab their prey.

68
00:10:14,080 --> 00:10:17,152
And when there are no more lanternfish to be found,

69
00:10:19,200 --> 00:10:21,351
they turn on each other.

70
00:10:32,320 --> 00:10:35,916
This squid has caught a smaller one in its tentacles.

71
00:10:40,560 --> 00:10:42,677
To hide its capture from the rest,

72
00:10:42,760 --> 00:10:45,400
it releases a smokescreen of black ink.

73
00:10:58,200 --> 00:11:01,113
But then, an even bigger one challenges it

74
00:11:07,720 --> 00:11:09,996
and steals its catch.

75
00:11:18,800 --> 00:11:20,154
The Twilight Zone

76
00:11:20,240 --> 00:11:23,233
is the Humboldt squid's favourite hunting ground.

77
00:11:25,080 --> 00:11:26,514
They seldom go deeper

78
00:11:28,000 --> 00:11:31,277
into the world of perpetual blackness below.

79
00:11:36,520 --> 00:11:38,432
The Midnight Zone.

80
00:11:49,080 --> 00:11:51,754
Two-thirds of a mile from the surface,

81
00:11:51,840 --> 00:11:54,036
beyond the reach of the sun.

82
00:11:59,280 --> 00:12:01,715
A giant black void

83
00:12:01,800 --> 00:12:05,589
larger than all the rest of the world's habitat's combined.

84
00:12:10,840 --> 00:12:12,399
There's life here,

85
00:12:13,880 --> 00:12:15,599
but not as we know it.

86
00:12:26,680 --> 00:12:28,353
Alien-like creatures

87
00:12:28,440 --> 00:12:31,194
produce dazzling displays of light.

88
00:12:43,560 --> 00:12:46,598
Nearly all animals need to attract mates

89
00:12:46,680 --> 00:12:48,160
and repel predators.

90
00:12:51,000 --> 00:12:54,391
This language of light is so widespread here,

91
00:12:54,480 --> 00:12:58,872
that these signals are probably the commonest form of communication

92
00:12:59,920 --> 00:13:01,559
on the entire planet.

93
00:13:03,040 --> 00:13:05,600
And yet, we still know little about them.

94
00:13:29,840 --> 00:13:31,672
Hunters illuminate themselves,

95
00:13:31,760 --> 00:13:33,114
and by doing so

96
00:13:33,200 --> 00:13:35,510
attract inquisitive prey.

97
00:13:47,760 --> 00:13:49,956
This is fangtooth.

98
00:13:51,840 --> 00:13:55,550
It has the largest teeth for its size of any fish.

99
00:13:58,040 --> 00:14:01,477
There are pressure sensors all over its head and body

100
00:14:01,560 --> 00:14:04,951
which can detect anything moving in the surrounding water.

101
00:14:11,600 --> 00:14:15,150
It's the Midnight Zone's most voracious fish.

102
00:14:17,120 --> 00:14:20,318
But prey use light as a distraction.

103
00:14:25,000 --> 00:14:27,799
A decoy of luminous ink.

104
00:14:36,840 --> 00:14:39,196
Down here, in this blackness,

105
00:14:41,200 --> 00:14:44,796
creatures live beyond the normal rules of time.

106
00:14:51,360 --> 00:14:54,751
Siphonophores are virtually eternal.

107
00:14:54,840 --> 00:14:58,595
They repeatedly clone themselves,

108
00:14:58,760 --> 00:15:02,436
some eventually growing longer than a blue whale.

109
00:15:26,400 --> 00:15:29,438
Down here, it snows.

110
00:15:37,560 --> 00:15:40,473
Continuous clouds of organic debris

111
00:15:40,560 --> 00:15:43,200
drift slowly down from above.

112
00:15:50,280 --> 00:15:52,476
This is food,

113
00:15:52,560 --> 00:15:56,600
and a whole variety of filter feeders depend on it.

114
00:15:59,680 --> 00:16:00,955
Jellyfish.

115
00:16:09,400 --> 00:16:12,120
And delicate sea cucumbers.

116
00:16:30,960 --> 00:16:33,680
The 1% of marine snow they miss

117
00:16:34,400 --> 00:16:36,869
eventually settles on the sea floor.

118
00:17:04,560 --> 00:17:06,279
Over millions of years,

119
00:17:06,360 --> 00:17:10,877
it forms a layer of mud up to a mile thick.

120
00:17:15,080 --> 00:17:16,912
It's an empty plain

121
00:17:17,000 --> 00:17:19,879
that covers half the surface of our planet.

122
00:17:45,680 --> 00:17:49,833
The deep seabed may, at first, appear lifeless,

123
00:17:52,000 --> 00:17:56,438
but it's home to a unique cast of mud dwellers.

124
00:17:59,080 --> 00:18:00,594
The sea toad.

125
00:18:03,360 --> 00:18:07,240
It is an ambush predator with an enormous mouth

126
00:18:09,120 --> 00:18:11,157
and infinite patience.

127
00:18:21,720 --> 00:18:25,077
This fish has been living for so long here

128
00:18:25,160 --> 00:18:28,517
that its fins have changed into something more useful.

129
00:18:34,720 --> 00:18:35,949
Feet.

130
00:18:40,760 --> 00:18:43,958
They help it shuffle about on the sea floor.

131
00:19:04,080 --> 00:19:06,470
The flapjack octopus.

132
00:19:11,280 --> 00:19:13,840
It hovers just above the surface of the mud

133
00:19:13,920 --> 00:19:17,834
as it delicately sifts through it searching for worms.

134
00:19:21,200 --> 00:19:25,194
But it can jet away at the first sign of danger.

135
00:19:43,760 --> 00:19:46,798
A sixgill shark, as big as a great white.

136
00:19:48,360 --> 00:19:51,831
It may not have eaten for an entire year.

137
00:19:58,240 --> 00:20:00,277
It patrols the mud plains

138
00:20:00,360 --> 00:20:03,034
using a minimum amount of energy.

139
00:20:16,600 --> 00:20:17,750
High above,

140
00:20:17,840 --> 00:20:20,309
the carcass of a huge sperm whale

141
00:20:20,400 --> 00:20:22,517
is slowly decaying.

142
00:20:28,840 --> 00:20:32,117
This will be a bonanza for the creatures of the deep.

143
00:20:33,120 --> 00:20:34,349
Food.

144
00:20:34,920 --> 00:20:36,513
Thirty tonnes of it.

145
00:20:49,520 --> 00:20:53,480
Finally it settles on the ocean floor

146
00:20:55,080 --> 00:20:58,039
and its presence is soon detected.

147
00:21:07,280 --> 00:21:09,158
Sixgills sharks

148
00:21:09,240 --> 00:21:11,994
have an exceptionally acute sense of smell.

149
00:21:16,760 --> 00:21:20,754
Just 25 minutes after the whale's carcass arrives,

150
00:21:22,880 --> 00:21:24,758
a sixgill finds it.

151
00:21:45,840 --> 00:21:49,151
Each bite releases blood into the current.

152
00:22:30,600 --> 00:22:33,877
The news that food is here spreads quickly.

153
00:22:42,000 --> 00:22:45,516
Two more ravenous sixgills arrive.

154
00:22:54,120 --> 00:22:57,670
Within 12 hours, there are seven enormous sharks

155
00:22:57,760 --> 00:22:59,240
jostling with one another

156
00:22:59,320 --> 00:23:01,994
as they compete to tear off mouthfuls.

157
00:23:13,920 --> 00:23:16,480
No one is prepared to back off.

158
00:23:59,520 --> 00:24:01,273
Twenty-four hours later,

159
00:24:01,360 --> 00:24:04,273
and a third of the carcass has gone.

160
00:24:35,240 --> 00:24:37,471
The first arrival has gorged

161
00:24:37,560 --> 00:24:39,517
until it's completely full.

162
00:24:44,360 --> 00:24:46,033
This single meal

163
00:24:46,120 --> 00:24:49,636
may be enough to sustain it for a whole year.

164
00:24:55,760 --> 00:24:59,037
Now, the clean up team arrives.

165
00:25:02,120 --> 00:25:05,431
Spider crabs carrying coral in their hind legs,

166
00:25:06,040 --> 00:25:08,999
presumably as makeshift body armour.

167
00:25:17,080 --> 00:25:19,151
There are rock crabs here too.

168
00:25:21,640 --> 00:25:25,873
They probably detected the carcass almost as soon as the sharks,

169
00:25:27,240 --> 00:25:29,311
but they can't move as fast.

170
00:25:33,760 --> 00:25:37,197
A month on, and over 30 species of scavenger

171
00:25:37,280 --> 00:25:40,512
are clearing away the last edible fragments.

172
00:25:42,880 --> 00:25:46,874
But now, the scavengers are attracting their own predators.

173
00:25:53,080 --> 00:25:56,278
Scabbardfish, habitually swimming upright,

174
00:25:56,360 --> 00:25:58,716
are picking them off one by one.

175
00:26:19,440 --> 00:26:22,035
Some of the whale's teeth have been dislodged

176
00:26:22,120 --> 00:26:24,715
as the skeleton starts to fall apart.

177
00:26:28,120 --> 00:26:32,876
Four months later, there is nothing left but a few bones.

178
00:26:40,400 --> 00:26:42,357
But even they are food

179
00:26:46,600 --> 00:26:47,829
for something.

180
00:26:54,560 --> 00:26:56,313
Zombie worms.

181
00:27:00,240 --> 00:27:03,756
They tunnel into the bones by injecting acid

182
00:27:04,640 --> 00:27:08,554
and so reach the tiny amounts of fat that still remain there.

183
00:27:10,880 --> 00:27:12,439
It may take decades,

184
00:27:12,520 --> 00:27:16,514
but eventually, the last of the bones will crumble,

185
00:27:16,600 --> 00:27:21,072
and the whole 30-tonne carcass will have been recycled.

186
00:27:28,120 --> 00:27:31,397
A whale fall is a temporary oasis

187
00:27:31,480 --> 00:27:33,472
in the desert of the sea floor.

188
00:27:36,840 --> 00:27:39,560
But there are permanent oases here too.

189
00:27:53,760 --> 00:27:56,070
Rocks projecting above the mud

190
00:27:56,160 --> 00:27:59,471
provide anchorage for deep sea corals.

191
00:28:17,360 --> 00:28:21,070
As far down as three and a half miles,

192
00:28:21,160 --> 00:28:23,959
there are more species of coral in the deep

193
00:28:24,040 --> 00:28:26,509
than on shallow tropical reefs.

194
00:28:35,120 --> 00:28:38,909
Without sunlight, they rely solely on food

195
00:28:39,000 --> 00:28:40,559
drifting in the current.

196
00:28:43,840 --> 00:28:45,354
And they grow

197
00:28:45,520 --> 00:28:48,752
just a hair's breadth a year.

198
00:28:54,240 --> 00:28:58,029
But some of them can live for 4,000 years.

199
00:29:04,600 --> 00:29:07,638
They, like their shallow water relatives,

200
00:29:07,760 --> 00:29:11,151
provide homes for all kinds of other creatures.

201
00:29:36,480 --> 00:29:38,312
Growing among the corals,

202
00:29:38,400 --> 00:29:41,120
is one of the most beautiful of sponges.

203
00:29:44,600 --> 00:29:48,230
This is Venus' flower basket.

204
00:29:55,640 --> 00:29:57,791
These sponges have lodgers.

205
00:29:58,680 --> 00:29:59,875
Shrimps.

206
00:30:08,400 --> 00:30:10,551
There are plenty of predators on the reef

207
00:30:10,960 --> 00:30:12,917
so the shrimps are fortunate.

208
00:30:17,320 --> 00:30:19,357
Both this male and female,

209
00:30:19,440 --> 00:30:22,512
were swept into this sponge when they were tiny larvae,

210
00:30:22,720 --> 00:30:25,440
along with the minute particles of food

211
00:30:25,520 --> 00:30:27,432
on which the sponge feeds.

212
00:30:31,360 --> 00:30:35,195
They found each other and have been here ever since.

213
00:30:49,960 --> 00:30:51,997
Now, they're full-grown

214
00:30:52,080 --> 00:30:54,595
and the female is carrying eggs.

215
00:31:07,400 --> 00:31:11,599
Once hatched, the larvae will swim out through the sponge's walls.

216
00:31:17,840 --> 00:31:20,480
But the shrimps will never leave.

217
00:31:21,760 --> 00:31:22,910
They can't.

218
00:31:29,360 --> 00:31:33,240
They're now far too big to go out the way they came in.

219
00:31:33,840 --> 00:31:35,957
And, no doubt, they will live longer here

220
00:31:36,040 --> 00:31:40,557
than they would if they were wandering about on the reef unprotected.

221
00:31:53,280 --> 00:31:56,432
But how one of the simplest of all animals,

222
00:31:56,560 --> 00:32:01,077
a sponge, is able to build such a complex structure

223
00:32:01,520 --> 00:32:03,432
to the great benefit of the shrimps

224
00:32:05,160 --> 00:32:06,355
is a mystery.

225
00:32:07,280 --> 00:32:09,511
And, surely, a marvel.

226
00:32:26,120 --> 00:32:27,190
But today,

227
00:32:27,280 --> 00:32:31,069
their timeless world is being reduced to rubble.

228
00:32:39,040 --> 00:32:43,592
As over-fishing empties the surface waters of the seas,

229
00:32:43,720 --> 00:32:47,111
trawlers have started to ransack the deep.

230
00:32:50,360 --> 00:32:53,159
Now, countless numbers of the reefs

231
00:32:53,240 --> 00:32:55,675
that have flourished here for millennia

232
00:32:55,760 --> 00:32:57,672
lie in ruins.

233
00:33:27,040 --> 00:33:28,190
Over time,

234
00:33:28,280 --> 00:33:31,830
organic matter on the sea floor slowly decays

235
00:33:32,680 --> 00:33:34,000
producing methane.

236
00:34:35,720 --> 00:34:37,837
In the Gulf of Mexico,

237
00:34:37,920 --> 00:34:41,755
these eruptions also release a super salty liquid.

238
00:34:49,840 --> 00:34:50,990
Brine.

239
00:35:02,000 --> 00:35:04,720
Five times heavier than sea water,

240
00:35:05,360 --> 00:35:08,637
it accumulates in great pools on the sea floor.

241
00:35:14,320 --> 00:35:17,040
It's difficult to make sense of the sight.

242
00:35:24,120 --> 00:35:27,192
A lake of concentrated salt water,

243
00:35:27,280 --> 00:35:29,078
fifteen metres deep,

244
00:35:30,080 --> 00:35:31,673
at the bottom of the sea.

245
00:35:39,520 --> 00:35:43,070
Around its margin, perhaps even more strangely,

246
00:35:43,160 --> 00:35:45,720
there is a profusion of life.

247
00:35:52,680 --> 00:35:56,799
Giant mussels that can live or grow for a century or more,

248
00:35:56,880 --> 00:35:58,439
pack tightly together,

249
00:35:58,520 --> 00:36:02,514
dwarfing the shrimps and squat lobsters that feed around them.

250
00:36:31,120 --> 00:36:34,272
Cutthroat eels, scavengers,

251
00:36:34,360 --> 00:36:36,591
come to the shores of the brine lake

252
00:36:36,680 --> 00:36:38,512
in search of something edible.

253
00:36:47,040 --> 00:36:49,919
Some even venture into the brine.

254
00:37:23,360 --> 00:37:27,798
Spending too long in it can send an eel into toxic shock.

255
00:37:39,640 --> 00:37:42,553
Its only hope is to rise above it.

256
00:37:57,120 --> 00:37:58,713
It manages to escape.

257
00:38:07,840 --> 00:38:09,718
Others are not so lucky.

258
00:38:17,040 --> 00:38:19,396
The brine embalms their bodies,

259
00:38:21,200 --> 00:38:26,229
and the casualties of decades accumulate around the margins.

260
00:38:46,080 --> 00:38:49,676
But parts of the deep are even more hostile.

261
00:38:57,200 --> 00:38:58,350
In places,

262
00:38:58,440 --> 00:39:03,310
gigantic cracks stretch for many miles across the ocean floor.

263
00:39:18,120 --> 00:39:22,000
Canyons that plunge towards the centre of the earth.

264
00:39:29,360 --> 00:39:31,477
Scans from survey vessels

265
00:39:31,560 --> 00:39:35,031
make it possible to graphically reconstruct an image

266
00:39:35,120 --> 00:39:37,635
of this vast submarine landscape.

267
00:39:45,240 --> 00:39:48,438
The deepest of all, at almost seven miles,

268
00:39:48,520 --> 00:39:51,399
is the Mariana Trench in the Pacific Ocean.

269
00:39:57,160 --> 00:40:00,710
Even Mount Everest could disappear inside it.

270
00:40:15,720 --> 00:40:19,111
Down here, in these deep ravines,

271
00:40:19,200 --> 00:40:23,513
it was once thought that nothing whatever could possibly survive.

272
00:40:30,200 --> 00:40:32,999
But there is life even here.

273
00:40:39,480 --> 00:40:41,312
A kind of sea slug.

274
00:40:48,840 --> 00:40:51,116
A so-called sea pig.

275
00:40:53,000 --> 00:40:55,356
They, and other simple creatures,

276
00:40:55,440 --> 00:41:00,674
manage to survive on the miniscule amount of food that drifts down here.

277
00:41:04,040 --> 00:41:05,679
Like this starfish,

278
00:41:05,760 --> 00:41:09,754
they can withstand pressure equivalent of 50 jumbo jets

279
00:41:09,840 --> 00:41:12,036
stacked on top of one another.

280
00:41:33,120 --> 00:41:34,918
A remote camera probe

281
00:41:35,000 --> 00:41:38,391
reveals the most extraordinary discovery of all.

282
00:41:45,600 --> 00:41:48,832
The ethereal snailfish.

283
00:41:52,480 --> 00:41:54,472
At five miles down,

284
00:41:54,560 --> 00:41:58,474
this is the deepest living fish so far discovered.

285
00:42:04,560 --> 00:42:06,199
No one imagined

286
00:42:06,280 --> 00:42:09,159
than an animal as complex as a fish

287
00:42:09,240 --> 00:42:12,278
could exist in such extreme pressures.

288
00:42:24,320 --> 00:42:25,993
From the greatest depths

289
00:42:26,080 --> 00:42:28,959
to the uppermost limit of the Twilight Zone,

290
00:42:29,040 --> 00:42:32,317
it seems that there is nowhere in the deep sea

291
00:42:32,400 --> 00:42:35,234
where life of some kind can't survive.

292
00:42:39,880 --> 00:42:40,996
And we now think

293
00:42:41,080 --> 00:42:44,630
that the deep sea may well be where life on Earth began.

294
00:42:58,520 --> 00:42:59,590
Here,

295
00:42:59,680 --> 00:43:04,391
in a world hidden within the greatest geological feature on Earth,

296
00:43:07,520 --> 00:43:11,150
running right down the middle of the world's oceans,

297
00:43:11,240 --> 00:43:13,516
an underwater mountain range

298
00:43:13,640 --> 00:43:15,757
spanning the entire globe.

299
00:43:20,720 --> 00:43:22,598
The mid-ocean ridge.

300
00:43:36,560 --> 00:43:38,153
In the South Pacific,

301
00:43:38,240 --> 00:43:41,039
the ocean floor is being torn apart.

302
00:44:53,440 --> 00:44:56,558
Over three quarters of the planet's volcanic activity

303
00:44:56,640 --> 00:44:58,791
occurs in the deep.

304
00:45:05,560 --> 00:45:09,270
Almost all of it along the mid-ocean ridge.

305
00:45:13,240 --> 00:45:15,994
But from this titanic violence

306
00:45:16,080 --> 00:45:18,037
come great riches.

307
00:45:26,920 --> 00:45:30,516
Gases and scalding water gush up through the crevices.

308
00:45:39,760 --> 00:45:42,275
Minerals condensing from these jets

309
00:45:42,360 --> 00:45:44,192
build up great chimneys.

310
00:45:45,640 --> 00:45:47,472
Hydrothermal vents.

311
00:45:51,280 --> 00:45:53,590
This one, 30 metres tall,

312
00:45:53,680 --> 00:45:55,672
has been named "Godzilla".

313
00:46:04,040 --> 00:46:06,316
Astonishingly, we now know

314
00:46:06,400 --> 00:46:10,394
that they hold as much life as tropical rainforests.

315
00:46:18,120 --> 00:46:21,875
In places, half a million individual animals

316
00:46:21,960 --> 00:46:24,839
are crammed into a single square metre.

317
00:46:37,240 --> 00:46:40,836
They depend entirely for their food on bacteria.

318
00:46:43,320 --> 00:46:45,596
And they feed on chemicals

319
00:46:45,680 --> 00:46:48,354
dissolved in the searingly hot fluid.

320
00:46:55,080 --> 00:46:58,630
Crabs consume the bacterial mats

321
00:46:58,720 --> 00:47:00,632
that coat their shells.

322
00:47:14,000 --> 00:47:16,799
Others maintain bacterial cultures,

323
00:47:16,880 --> 00:47:19,349
actually within their bodies.

324
00:47:25,720 --> 00:47:29,236
Shrimps carry such cultures in their mouth parts.

325
00:47:29,880 --> 00:47:32,714
But that is a strategy fraught with danger.

326
00:47:37,120 --> 00:47:41,160
To provide sustenance for these microbes,

327
00:47:41,320 --> 00:47:44,392
the shrimps must dash into the hot vents,

328
00:47:46,360 --> 00:47:49,478
and that risks being boiled alive.

329
00:48:03,000 --> 00:48:04,480
In the last decade,

330
00:48:04,560 --> 00:48:08,474
the number of hydrothermal vents discovered has doubled.

331
00:48:16,360 --> 00:48:20,513
Every one has its own unique character and community.

332
00:48:27,080 --> 00:48:31,154
But, perhaps, the most important one of all is in the Atlantic.

333
00:48:32,560 --> 00:48:36,110
It has been named "The Lost City".

334
00:48:39,560 --> 00:48:42,200
Within its 60-metre towers,

335
00:48:42,280 --> 00:48:45,796
something truly extraordinary is taking place.

336
00:48:49,440 --> 00:48:52,319
Under extremes of pressure and temperature,

337
00:48:52,560 --> 00:48:54,438
hydrocarbons,

338
00:48:54,520 --> 00:48:58,799
the molecules that are the basic component of all living things,

339
00:48:59,640 --> 00:49:02,712
are being created spontaneously.

340
00:49:13,920 --> 00:49:17,197
Indeed, many scientists now believe

341
00:49:17,280 --> 00:49:22,878
that life on Earth may have begun around a vent like this

342
00:49:23,280 --> 00:49:25,476
four billion years ago.

343
00:49:44,440 --> 00:49:47,194
We now know that there are deep seas

344
00:49:47,280 --> 00:49:50,318
on the moons of Jupiter and Saturn.

345
00:49:57,200 --> 00:50:01,717
If life can exist under such extreme conditions down here,

346
00:50:02,000 --> 00:50:06,438
then surely it could exist somewhere out there.

347
00:50:31,440 --> 00:50:33,875
The team spent more than a thousand hours

348
00:50:33,960 --> 00:50:35,360
filming in the deep ocean,

349
00:50:35,600 --> 00:50:38,399
mostly from the research vessel Alucia,

350
00:50:38,480 --> 00:50:42,713
and her twin submersibles, Deep Rover and Nadir.

351
00:50:48,000 --> 00:50:51,152
Their most ambitious mission was to Antarctica,

352
00:50:52,240 --> 00:50:55,199
hoping to film life two-thirds of a mile down,

353
00:50:55,280 --> 00:50:57,397
something never attempted before.

354
00:51:02,520 --> 00:51:05,194
We honestly do not know what we're gonna find down there.

355
00:51:05,280 --> 00:51:08,557
We're going to a place that has never been explored.

356
00:51:08,680 --> 00:51:11,354
There could be nothing, there could be a carpet of life.

357
00:51:11,440 --> 00:51:14,035
There could be anything in between. Who knows?

358
00:51:18,160 --> 00:51:20,720
It's a huge technical challenge.

359
00:51:27,400 --> 00:51:29,039
The water temperature here

360
00:51:29,120 --> 00:51:32,670
can reach minus 1.8 degree centigrade.

361
00:51:37,760 --> 00:51:39,035
No one knows for sure

362
00:51:39,120 --> 00:51:42,113
how the subs will cope with this extreme environment.

363
00:51:47,480 --> 00:51:49,870
Okay, all right, I'm gonna soak it up. Uh...

364
00:51:49,960 --> 00:51:51,599
Okay.

365
00:51:51,720 --> 00:51:54,440
Just half an hour into the very first dive,

366
00:51:54,520 --> 00:51:57,354
a puddle is forming on the floor of the sub.

367
00:52:00,640 --> 00:52:02,677
Orla confirms it's sea water.

368
00:52:04,080 --> 00:52:08,120
Yeah, roger, I'm just trying to soak up this puddle of water

369
00:52:08,560 --> 00:52:10,119
and then see if any more comes.

370
00:52:11,320 --> 00:52:14,472
They must find the leak and repair it fast.

371
00:52:14,800 --> 00:52:16,917
DOHERTY: Uh, are you gonna...yeah.

372
00:52:17,000 --> 00:52:17,990
RALPH: Yeah.

373
00:52:18,080 --> 00:52:20,879
When you're 450 metres in a small bubble

374
00:52:20,960 --> 00:52:22,155
and water's coming in...

375
00:52:22,240 --> 00:52:26,120
That's a half an hour straight shot back up to the surface.

376
00:52:26,200 --> 00:52:28,954
You're kind of thinking about, "Are we gonna fill up with water?

377
00:52:29,040 --> 00:52:31,475
"And if we are, there's no way out."

378
00:52:32,400 --> 00:52:33,720
Yeah.

379
00:52:33,800 --> 00:52:36,679
The sub pilots are well drilled for emergencies.

380
00:52:39,720 --> 00:52:41,791
RALPH: Pass it over. DOHERTY: Yeah.

381
00:52:42,440 --> 00:52:45,399
Ralph quickly finds the flood and fixes it.

382
00:52:47,400 --> 00:52:50,996
He made it all seem absolutely ordinary and normal.

383
00:52:51,080 --> 00:52:53,151
And, "I've got this covered. Don't you worry."

384
00:52:53,240 --> 00:52:54,959
And within 20 minutes, he did.

385
00:53:00,280 --> 00:53:03,876
The waters of the Antarctic Sound are potentially rich,

386
00:53:03,960 --> 00:53:05,440
but also treacherous.

387
00:53:07,040 --> 00:53:11,353
The Sound is ominously known as "Iceberg Alley".

388
00:53:12,920 --> 00:53:14,400
We've got to find a place where we can get

389
00:53:14,480 --> 00:53:16,153
the submarines down and up safely

390
00:53:16,240 --> 00:53:18,709
without any icebergs coming along and bowling them over.

391
00:53:18,800 --> 00:53:21,759
Uh, I've got a feeling it's going to be a bit like a game of Space Invaders.

392
00:53:23,280 --> 00:53:25,749
BUCK TAYLOR: A metre cube of ice weighs a tonne.

393
00:53:25,840 --> 00:53:28,912
You start to, sort of, grinding that around the sphere, it's...

394
00:53:29,000 --> 00:53:31,515
It's delicate. It's like a big Fabergé egg.

395
00:53:34,360 --> 00:53:35,555
One dive brings them

396
00:53:35,640 --> 00:53:38,633
right up to the underside face of an iceberg.

397
00:53:41,480 --> 00:53:44,678
DOHERTY: There are icebergs up there that are the size of a small car

398
00:53:44,760 --> 00:53:47,355
and then there are icebergs up there that are

399
00:53:47,440 --> 00:53:49,671
the size of Hyde Park.

400
00:53:49,760 --> 00:53:50,910
Enormous.

401
00:53:52,560 --> 00:53:55,029
Conditions here can change in an instant.

402
00:53:56,360 --> 00:53:58,511
The captain radios down to the subs.

403
00:54:02,720 --> 00:54:03,710
SUB PILOT: Yeah, roger that.

404
00:54:05,360 --> 00:54:07,511
RALPH: We've currently got a couple of big icebergs

405
00:54:07,600 --> 00:54:08,716
coming down the channel.

406
00:54:08,840 --> 00:54:11,036
And it looks like they're on a collision course.

407
00:54:14,920 --> 00:54:16,718
The impact of two icebergs

408
00:54:16,800 --> 00:54:19,952
colliding overhead is clearly heard.

409
00:54:23,280 --> 00:54:24,600
That is ice.

410
00:54:26,440 --> 00:54:28,477
With icebergs colliding above,

411
00:54:28,560 --> 00:54:30,199
and the weather turning fast,

412
00:54:30,280 --> 00:54:32,237
the subs are quickly recalled.

413
00:54:39,400 --> 00:54:41,312
Once again, their efforts are thwarted.

414
00:54:52,560 --> 00:54:54,677
Finally, after two weeks,

415
00:54:54,760 --> 00:54:57,400
conditions are just right.

416
00:54:57,560 --> 00:55:00,792
Once again, the team attempt their 1,000-metre dive

417
00:55:00,880 --> 00:55:02,473
in Iceberg Alley.

418
00:55:06,160 --> 00:55:08,197
An hour after leaving the surface,

419
00:55:08,280 --> 00:55:10,033
they close in on their goal.

420
00:55:14,000 --> 00:55:15,229
Nine-nine-nine.

421
00:55:19,160 --> 00:55:20,560
RALPH: Control, control.

422
00:55:20,640 --> 00:55:27,479
This is Nadir. On bottom. Depth one-zero-zero-zero metres.

423
00:55:27,560 --> 00:55:31,031
Roger. Depth 1,000 metres. Control out.

424
00:55:31,120 --> 00:55:32,349
TAYLOR: New record.

425
00:55:34,160 --> 00:55:37,471
First manned sub-dive to 1,000 metres in Antarctica.

426
00:55:39,800 --> 00:55:42,713
At the bottom of the ocean, at the end of the world,

427
00:55:42,800 --> 00:55:45,872
the amount of life they find is astonishing.

428
00:55:51,680 --> 00:55:54,036
But they're equally astonished to find that

429
00:55:54,120 --> 00:55:56,396
two-thirds of a mile from the surface,

430
00:55:56,480 --> 00:55:59,234
icebergs are still a danger.

431
00:56:00,640 --> 00:56:03,838
Rocks can drop from them as they melt.

432
00:56:03,920 --> 00:56:06,230
And one lands right in front of the sub.

433
00:56:09,280 --> 00:56:12,114
I don't think many people who are diving subs

434
00:56:12,200 --> 00:56:15,830
ever consider big lumps of rock landing on them.

435
00:56:15,920 --> 00:56:18,754
Um, it's... It's not your normal risk.

436
00:56:19,520 --> 00:56:20,749
If it had hit the sphere,

437
00:56:20,840 --> 00:56:23,674
there's a good chance it would've put a nice scratch down it.

438
00:56:23,760 --> 00:56:27,231
If something of 10, 15, 20 tonne had hit the sub,

439
00:56:27,320 --> 00:56:29,039
it would completely destroy it.

440
00:56:33,040 --> 00:56:34,918
But over the following dives,

441
00:56:35,000 --> 00:56:37,799
the team learns it's these very drop stones

442
00:56:37,880 --> 00:56:40,918
that enrich the Antarctic deep seabed

443
00:56:42,240 --> 00:56:44,197
creating firm anchor points

444
00:56:44,280 --> 00:56:46,033
for life to thrive.

445
00:56:50,400 --> 00:56:52,869
Proof that the only way to fully appreciate

446
00:56:52,960 --> 00:56:56,078
the complexity and abundance of life in the deep,

447
00:56:56,160 --> 00:56:58,550
is to go there ourselves.

448
00:57:06,840 --> 00:57:10,436
Next time, we travel to bustling coral reefs.

449
00:57:16,880 --> 00:57:20,556
Here, animals must go to extraordinary lengths

450
00:57:21,840 --> 00:57:26,039
to get ahead of the competition in these crowded cities.