0:00:17 > 0:00:20Our planet is unique.
0:00:20 > 0:00:23An extraordinary piece of engineering,
0:00:23 > 0:00:26over four and a half billion years old.
0:00:28 > 0:00:33And to show you how it works, we've created something rather special.
0:00:36 > 0:00:38We've collected the latest information
0:00:38 > 0:00:40from scientists around the world.
0:00:40 > 0:00:42We've added satellite maps, sonar and radar images
0:00:42 > 0:00:45and we've brought it all together to make this.
0:00:47 > 0:00:50We've created a virtual planet earth.
0:00:52 > 0:00:59In here we can dismantle the earth's machinery piece by piece,
0:00:59 > 0:01:03and see how an enormous energy source,
0:01:03 > 0:01:06buried deep within the planet, shapes our world,
0:01:06 > 0:01:09up here on the surface.
0:01:10 > 0:01:15Many of the most powerful effects happen on the ocean floor.
0:01:19 > 0:01:23And it was the movement of the sea bed 80 miles off the coast of Japan
0:01:23 > 0:01:27that triggered the tsunami in March 2011.
0:01:28 > 0:01:32So to reveal how the earth machine works,
0:01:32 > 0:01:35we need to drain the oceans.
0:01:48 > 0:01:52Every now and then, we get a glimpse of what's below the surface.
0:01:55 > 0:01:59We can shine a light or we can go down in a sub.
0:02:00 > 0:02:03But it's hard to get the whole picture.
0:02:03 > 0:02:07The more I think about the sea beneath me,
0:02:07 > 0:02:08the more questions I have.
0:02:08 > 0:02:11What if we could drain the oceans?
0:02:14 > 0:02:16What would we see? What surprises are down there?
0:02:16 > 0:02:18And what dangers lurk?
0:02:20 > 0:02:23- Have you ever had anybody panic completely?- Yes.
0:02:25 > 0:02:29Why does more volcanic activity take place underwater than on land?
0:02:29 > 0:02:31Seeing as I'm already dressed...
0:02:31 > 0:02:35What's one of the biggest underwater threats to the Internet...
0:02:35 > 0:02:39- If that phone goes...? - If that phone goes, I'll get all...
0:02:39 > 0:02:42..and our lives?
0:02:46 > 0:02:49How can chimneys spout gold
0:02:49 > 0:02:51and be home to snails made of metal?
0:02:51 > 0:02:55And why have more men been to the moon
0:02:55 > 0:02:59than to the deepest point in our oceans?
0:02:59 > 0:03:03We've combined the latest scientific data
0:03:03 > 0:03:06with some very clever computer software
0:03:06 > 0:03:09to show you the wonders of the deep ocean.
0:03:09 > 0:03:14Wonders created by a machine hidden beneath the sea floor.
0:03:14 > 0:03:18A machine so powerful, it not only affects all our lives,
0:03:18 > 0:03:20it drives the planet.
0:03:20 > 0:03:23We're going to take you on a journey to the bottom of the sea
0:03:23 > 0:03:26and beyond even that.
0:03:50 > 0:03:53On Friday 11th March, 2011...
0:03:58 > 0:04:02..a devastating tsunami crashed into the coast of Japan.
0:04:05 > 0:04:09In some places, the waves reached 98 feet high.
0:04:13 > 0:04:16It was caused by a powerful earthquake
0:04:16 > 0:04:18that measured nine on the Richter scale.
0:04:39 > 0:04:44This was the worst earthquake to hit Japan for over 100 years.
0:04:46 > 0:04:50The death toll was at least 25,000.
0:04:54 > 0:04:58This was the earth machine in action on an awesome scale.
0:05:00 > 0:05:04The source of this devastation was 80 miles offshore
0:05:04 > 0:05:07and deep below the surface of the ocean.
0:05:18 > 0:05:20Oh, yeah, that's me. I'm doing that.
0:05:23 > 0:05:24I did that then.
0:05:26 > 0:05:29In order to show you how the earth machine works
0:05:29 > 0:05:34and see how it affects us, we need first to get down to the ocean floor.
0:05:34 > 0:05:38And we start, I'm delighted to say, down there.
0:05:38 > 0:05:40The English Channel.
0:05:40 > 0:05:44I know it may not be the most obvious place
0:05:44 > 0:05:47to start a journey to the bottom of the sea, but bear with me.
0:05:50 > 0:05:55The waters between Dover and Calais are about 40 metres deep,
0:05:55 > 0:05:58which, in sea terms, is pretty shallow.
0:06:03 > 0:06:07That's because this part of the seabed is just flooded land.
0:06:07 > 0:06:089,000 years ago you could walk -
0:06:08 > 0:06:12give or take the odd river - from England to France.
0:06:17 > 0:06:20Now we can reveal what that looks like today.
0:06:22 > 0:06:24So, let's drain it and have a look.
0:06:39 > 0:06:42With a bit of computer technology, we can do in seconds
0:06:42 > 0:06:46what it takes the earth machine thousands of years to do.
0:06:57 > 0:07:03And, well, frankly, the English Channel is a bit of a mess.
0:07:03 > 0:07:05From up here, it looks like a scrap yard.
0:07:07 > 0:07:13There are over 8,000 shipwrecks in this stretch of water alone.
0:07:18 > 0:07:21What the Channel does show us is that, over time,
0:07:21 > 0:07:25the boundaries of the land we live on can change.
0:07:25 > 0:07:28The earth machine has such power
0:07:28 > 0:07:31that it continually changes the surface of the earth.
0:07:48 > 0:07:52The earth's surface is made up of a series of giant tectonic plates
0:07:52 > 0:07:54which are constantly on the move.
0:07:58 > 0:08:01Over time, as the continents have shifted
0:08:01 > 0:08:03and sea levels rise and fall,
0:08:03 > 0:08:06what was once land has sunk underwater.
0:08:15 > 0:08:18As we begin to drain the ocean, the first thing we see
0:08:18 > 0:08:22is that the continents we live on extend far out from the shore.
0:08:29 > 0:08:31In some places, hundreds of miles.
0:08:35 > 0:08:40This submerged land makes up the continental shelf.
0:08:51 > 0:08:55The continental shelf has become one of the most valuable places on earth.
0:08:55 > 0:08:58And there's a very good reason for this.
0:08:58 > 0:09:02If we plot all the oil and gas platforms found out at sea,
0:09:02 > 0:09:05it becomes clear that almost all of these
0:09:05 > 0:09:08are concentrated on the continental shelf.
0:09:14 > 0:09:17For millions of years, dead sea creatures
0:09:17 > 0:09:21and sediment from the land have rained down on the sea bed.
0:09:22 > 0:09:27With time, pressure and heat, this debris turns into oil
0:09:27 > 0:09:30and this has made the shelf immensely valuable.
0:09:32 > 0:09:35Today, these large oil and gas fields
0:09:35 > 0:09:37help fuel our cars...
0:09:39 > 0:09:41..boats...
0:09:41 > 0:09:43and jets.
0:09:52 > 0:09:56As we drain the water from the seas and leave the shore far behind,
0:09:56 > 0:09:59we come to the edge of the continental land mass,
0:09:59 > 0:10:03where the sea bed slopes steeply down to the ocean floor.
0:10:07 > 0:10:12The edge of the continental shelf is often unstable and easily eroded.
0:10:12 > 0:10:15It's here that we find some of the shelf's biggest features.
0:10:20 > 0:10:22Deep canyons.
0:10:46 > 0:10:49To get an idea of the scale of these underwater canyons,
0:10:49 > 0:10:54think the Grand Canyon in the USA.
0:10:54 > 0:11:00It's one mile deep, 18 miles wide and 277 miles long.
0:11:03 > 0:11:08Yet the canyons on the continental shelf can be even larger.
0:11:11 > 0:11:14Anyone can visit the Grand Canyon. I've done it myself.
0:11:14 > 0:11:19But to see these underwater canyons is a much more serious challenge.
0:11:31 > 0:11:33This is Monterey Bay, California,
0:11:33 > 0:11:38and just out there is one of the wonders of the ocean.
0:11:38 > 0:11:43To show you it, I need a pretty specialised vehicle. This.
0:11:50 > 0:11:52Oh, yeah.
0:11:52 > 0:11:54'It may look like a glass bubble but this little baby
0:11:54 > 0:12:01'is actually a two-man sub that can dive nearly one mile beneath the surface.
0:12:01 > 0:12:06'It's one of the world's most technologically advanced glass bubbles.
0:12:08 > 0:12:09'And it needs to be,
0:12:09 > 0:12:14'because to get to the bottom of an undersea canyon is a deep, dark
0:12:14 > 0:12:16'and potentially dangerous dive.'
0:12:18 > 0:12:23You've got the fire extinguisher, mask, oxygen system. And that's it.
0:12:24 > 0:12:27Our visibility is good.
0:12:29 > 0:12:31'Now, which way is the ocean?'
0:12:33 > 0:12:37'Luckily, I'm in the capable hands of pilot Mike Caplehorn.'
0:12:43 > 0:12:49'Monterey Bay Canyon begins just a few hundred metres off the shore,
0:12:49 > 0:12:51'so we don't have to go out too far.'
0:12:53 > 0:12:56I'm steering 203, south.
0:12:56 > 0:12:57Roger, stand by.
0:13:01 > 0:13:04'The support diver unhooks us from the boat
0:13:04 > 0:13:07'and we'll then head down into the abyss.'
0:13:07 > 0:13:09This is where it's going to come up the window
0:13:09 > 0:13:13and, I presume, feel pretty unnerving.
0:13:13 > 0:13:16- Mike, have you ever had anyone panic completely?- Yes.
0:13:18 > 0:13:19OK...
0:13:19 > 0:13:23'I wasn't scared, I was just sweating...cos it's warm in there.'
0:13:23 > 0:13:26My main vents are about to be closed.
0:13:26 > 0:13:29'High speed with four wheels on land,
0:13:29 > 0:13:32'not usually a problem for me. But trapped in here,
0:13:32 > 0:13:37'heading vertically down, it was a BIT scary.'
0:13:37 > 0:13:39There goes the sun.
0:13:45 > 0:13:49- That's it. We are now, just, officially underwater.- Yeah.
0:13:50 > 0:13:55I'm trying very hard to be cool about this, but arrrhhh!
0:13:56 > 0:13:58OK, we're commencing our descent.
0:14:01 > 0:14:03Comm is good and we are tracking you.
0:14:03 > 0:14:06O2 is 19.2...
0:14:06 > 0:14:10'The Monterey Canyon is deep.
0:14:10 > 0:14:14'From the surface of the ocean to the bottom of the canyon, it's over two miles.'
0:14:14 > 0:14:16Yeah, Deep Sea, Deep Sea...
0:14:16 > 0:14:18Heading 160.
0:14:26 > 0:14:28'We're now more than 300 feet down,
0:14:28 > 0:14:32'rapidly descending into the mouth of the canyon.'
0:14:34 > 0:14:37There's the monster.
0:14:37 > 0:14:39Two miles deep from the surface of the sea
0:14:39 > 0:14:42down to the bottom of the deepest part.
0:14:42 > 0:14:45That's 3km that way.
0:14:50 > 0:14:54'You'd think the water down here would be crystal clear,
0:14:54 > 0:14:56'but it's like a snow storm.
0:14:56 > 0:14:59'Much of this sediment has been washed off the land
0:14:59 > 0:15:01'and funnelled into the deep,
0:15:01 > 0:15:04'a process that helps carve out the canyon.'
0:15:12 > 0:15:15- Look at the jellyfish. See them? - Where, where? Oh, God!
0:15:15 > 0:15:19- That is enormous!- It is very big.
0:15:27 > 0:15:31OK, I'm going a little bit deeper, see if we can get more vertical.
0:15:33 > 0:15:37'The sun's rays can't penetrate this far down.
0:15:37 > 0:15:43'We're now 700 feet down and can only see as far as our lights can shine.
0:15:46 > 0:15:51'It's cold, dark and just a bit intimidating.
0:15:53 > 0:15:56'This is where creatures glow in the dark.
0:16:00 > 0:16:03'I'm in the realm of aliens.'
0:16:03 > 0:16:05That one flashed neon when it hit the light.
0:16:05 > 0:16:07Lit up.
0:16:12 > 0:16:14'So far, so good,
0:16:14 > 0:16:17'and I was just about getting used to this deep ocean business,
0:16:17 > 0:16:20- 'when, all of a sudden...' - CRACK
0:16:20 > 0:16:22What was that?
0:16:22 > 0:16:25That was just a crack in the glass, nothing to worry about.
0:16:25 > 0:16:29That's not a sound I want to hear! Don't ever say that to me again!
0:16:29 > 0:16:32OK, we'll turn around and head for the wall.
0:16:34 > 0:16:39'Yeah, I hope Mike's a better pilot that he is comedian.
0:16:39 > 0:16:43'Because somewhere up in front of us is the wall of the canyon.
0:16:43 > 0:16:45'The visibility is getting worse.
0:16:45 > 0:16:48'This is where it gets tense.'
0:16:48 > 0:16:53If you go forward 200 south, 200 south.
0:17:03 > 0:17:06- That is it.- That's the wall?- That's the wall.
0:17:06 > 0:17:10Look at that. That really is the walls of a canyon.
0:17:14 > 0:17:17Mike, well done!
0:17:28 > 0:17:31'Mike tells me the walls extend for hundreds of feet below
0:17:31 > 0:17:35'and for miles either side but with the poor visibility
0:17:35 > 0:17:37'and the fact we can't go any deeper,
0:17:37 > 0:17:39'it's time to head back to the surface.'
0:17:49 > 0:17:52Oh, land! It's there.
0:17:56 > 0:17:58It might not be the most original thought
0:17:58 > 0:18:01but that really is another world down there.
0:18:01 > 0:18:04And bobbing about back up on the surface, waiting to be picked up,
0:18:04 > 0:18:07again, it's not the most original thought,
0:18:07 > 0:18:12but I felt like we were two returning astronauts in our capsule, all sealed in.
0:18:12 > 0:18:16I need a cup of tea more than anything else in the whole world.
0:18:17 > 0:18:20I've been lucky to get a glimpse of the canyon
0:18:20 > 0:18:23but there's only one way to see the whole thing.
0:18:26 > 0:18:30With our virtual earth, we can drain all the water from Monterey Bay Canyon.
0:18:37 > 0:18:41It took around ten million years to carve this canyon
0:18:41 > 0:18:45into the side of the continental shelf.
0:18:45 > 0:18:48But if you think THAT's big, just hold on.
0:18:48 > 0:18:51A few thousand miles northwest of California,
0:18:51 > 0:18:53just off the coast of Russia,
0:18:53 > 0:18:57there's a canyon that makes Monterey look like a teacup.
0:19:17 > 0:19:20The largest canyon on the planet is the Zhemchug.
0:19:20 > 0:19:24It's nearly two miles deep at its deepest point
0:19:24 > 0:19:29and 144 miles long and 62 miles wide.
0:19:29 > 0:19:32Of course, it's normally hidden by the Pacific Ocean
0:19:32 > 0:19:37but the Zhemchug is so wide it's impossible to see from one side to the other
0:19:37 > 0:19:40unless you are above the curvature of the Earth.
0:20:09 > 0:20:12So far on our journey to the bottom of the sea,
0:20:12 > 0:20:16we've drained the water from the beaches to the edge of the continental shelf.
0:20:16 > 0:20:19We've drained the water from the cliffs and canyons
0:20:19 > 0:20:22and now we've reached the floor of the deep ocean.
0:20:22 > 0:20:24For the first time, we can see direct evidence
0:20:24 > 0:20:29of the earth machine and how it affects this part of the sea floor.
0:20:29 > 0:20:32It's called the abyssal plain
0:20:32 > 0:20:35and it covers over half the planet's surface.
0:20:36 > 0:20:40For years, it was thought to be flat and lifeless,
0:20:40 > 0:20:45but in the middle of the Atlantic, you find one of the biggest geological features on the planet.
0:20:49 > 0:20:53It is one of the most important parts of the earth machine.
0:20:53 > 0:20:58This huge mountain range is called the Mid-Atlantic Ridge
0:20:58 > 0:21:03and it's one of the largest and most active geological structures
0:21:03 > 0:21:05in the entire solar system.
0:21:08 > 0:21:13It's part of a vast tear in the planet's surface -
0:21:13 > 0:21:17a single line of underwater mountains and volcanoes
0:21:17 > 0:21:22that runs for over 40,000 miles around the planet.
0:21:25 > 0:21:29At the mid-ocean ridge, lava forces its way up from below.
0:21:32 > 0:21:36It's supplied by the mantle, a searing-hot layer below the crust.
0:21:40 > 0:21:44This tear in the crust shows the power
0:21:44 > 0:21:47of the machine that drives planet earth.
0:21:50 > 0:21:52As the lava flows out,
0:21:52 > 0:21:56it spreads away from the centre of the ridge and cools.
0:22:00 > 0:22:03This pushes the whole sea floor ahead of it
0:22:03 > 0:22:07and creates incredible stresses and strains.
0:22:09 > 0:22:13This pressure triggers earthquakes and landslides,
0:22:13 > 0:22:17makes deep valleys and huge undersea mountains.
0:22:20 > 0:22:27This continuous process produces a square mile of new rock every year.
0:22:31 > 0:22:34If we travel north, up here we come to a place
0:22:34 > 0:22:37where the vast volcano range rises out of the water,
0:22:37 > 0:22:40creating an island like no other.
0:22:54 > 0:22:56Iceland.
0:23:02 > 0:23:06Iceland is the only place in the world where the mid-ocean ridge
0:23:06 > 0:23:11rises above the waves, exposing over 100 active volcanoes.
0:23:18 > 0:23:23At one time, this whole landscape would have been underwater.
0:23:23 > 0:23:25It's the closest I'll get to the ocean floor.
0:23:32 > 0:23:34Iceland gives me the chance to take a look
0:23:34 > 0:23:37at the mid-ocean ridge from the inside.
0:23:41 > 0:23:43That is Lake Thingvellir
0:23:43 > 0:23:46and this crack is part of the Mid-Atlantic Ridge.
0:23:46 > 0:23:49It's known locally as Silfra and it's considered
0:23:49 > 0:23:53one of the most beautiful and spectacular dives in the world.
0:23:53 > 0:23:56And seeing as I'm already dressed...
0:24:08 > 0:24:11'You can swim through the gap
0:24:11 > 0:24:14'between the two halves of the mid-ocean ridge.
0:24:14 > 0:24:18'They're moving apart by about an inch a year.'
0:24:18 > 0:24:21On this side, the United States.
0:24:21 > 0:24:25On that side, Europe.
0:24:25 > 0:24:27And they're just metres apart.
0:24:27 > 0:24:32'A couple of million years ago, there would have been lava pouring up through this crack.
0:24:32 > 0:24:36'Now it's cooled and solidified, it's left an incredible opportunity
0:24:36 > 0:24:40'for us to see inside the mid-ocean ridge.'
0:24:52 > 0:24:55Because the ground in Iceland is very thin -
0:24:55 > 0:24:58in some places only a few miles deep -
0:24:58 > 0:25:03you can see other effects caused by the volcanic machine below.
0:25:10 > 0:25:14The thermal power of the earth is evident everywhere here.
0:25:14 > 0:25:16This is one of Iceland's many famous geysers,
0:25:16 > 0:25:19and the way it works is actually pretty simple.
0:25:19 > 0:25:23It's like switching on a giant, instantly boiling kettle every few minutes.
0:25:23 > 0:25:26The rocks down there are at about 200 degrees centigrade.
0:25:26 > 0:25:30When water enters an underground chamber about 60 feet down,
0:25:30 > 0:25:33it's boiled instantly, so it expands hugely,
0:25:33 > 0:25:36it explodes into steam and fires out of the hole,
0:25:36 > 0:25:38creating this magnificent spectacle.
0:26:01 > 0:26:05Surprisingly, geysers exist all along the mid-ocean ridge.
0:26:18 > 0:26:22One mile down, on the ocean floor, they look like this.
0:26:22 > 0:26:24They're called black smokers
0:26:24 > 0:26:27and they were only discovered about 30 years ago.
0:26:40 > 0:26:44Superheated water laced with precious minerals -
0:26:44 > 0:26:48gold, silver and iron - races up from the volcanic rocks below.
0:26:51 > 0:26:55As they hit the cold sea water, the minerals turn black.
0:26:55 > 0:27:01They then solidify into chimneys that can grow up to 180 feet high.
0:27:05 > 0:27:07The chimneys would be worth a fortune
0:27:07 > 0:27:11but right now they're just too difficult to mine.
0:27:13 > 0:27:17But scientists have recently discovered a little chap
0:27:17 > 0:27:19who's been mining the black smokers for years.
0:27:26 > 0:27:29A metal snail.
0:27:31 > 0:27:34This snail makes its shell and the scales on its foot
0:27:34 > 0:27:38from the metals in the water around it.
0:27:38 > 0:27:41The scaly-foot is the most extraordinary thing I've found.
0:27:42 > 0:27:46These scaly-foot snails were discovered nearly two miles down
0:27:46 > 0:27:49in the ocean by Professor Cindy Van Dover.
0:27:52 > 0:27:55We were sampling the large common snails,
0:27:55 > 0:27:58and in the handful of snails that we brought to the surface,
0:27:58 > 0:28:02we discovered these small, scaly-foot snails.
0:28:02 > 0:28:06We wondered for a couple of weeks, what could they be? We didn't know.
0:28:08 > 0:28:12There is no other known snail that has a metal-fortified shell.
0:28:14 > 0:28:20Even in the animal kingdom, we don't know of anything else that has a metal-fortified shell.
0:28:20 > 0:28:23The animals have spent evolutionary time
0:28:23 > 0:28:25honing the composition of their shell
0:28:25 > 0:28:28to make it deflect predators, to make it strong.
0:28:28 > 0:28:30So, it's like having armour.
0:28:34 > 0:28:37What a weird little fellow.
0:28:37 > 0:28:40Each time scientists visit these volcanic worlds,
0:28:40 > 0:28:45over half the animals they find are unknown to science.
0:28:45 > 0:28:48Here's this little animal that sits in this warm water that's coming out,
0:28:48 > 0:28:52that's metal-rich, and it's sitting there mining these metals.
0:28:52 > 0:28:53That is extraordinary.
0:29:02 > 0:29:07Super snails and precious metals are just a tiny part of the riches
0:29:07 > 0:29:10produced by the volcanic machine below.
0:29:10 > 0:29:14A machine that has a much more destructive side.
0:29:17 > 0:29:21When the new sea floor spreads out from the mid-ocean ridge,
0:29:21 > 0:29:26the sea floor buckles, and causes massive undersea movements and landslides.
0:29:34 > 0:29:39Although these happen miles beneath the ocean, they can affect us all.
0:29:47 > 0:29:50You might not know this, but pretty much all Internet traffic
0:29:50 > 0:29:53is carried between the continents by undersea cables.
0:29:53 > 0:29:58In December 2006, nine fibre optic cables
0:29:58 > 0:30:01between Taiwan and the Philippines suddenly went dead.
0:30:01 > 0:30:03Computers across Asia crashed.
0:30:03 > 0:30:07Engineers soon discovered that the cables had been severed.
0:30:07 > 0:30:10But...by what?
0:30:12 > 0:30:15Let's take a look beneath the waves.
0:30:20 > 0:30:23Sediment collects in huge quantities
0:30:23 > 0:30:26on the edge of underwater ledges and canyons.
0:30:36 > 0:30:40Earthquakes then trigger underwater landslides.
0:30:45 > 0:30:47On this occasion, just off the coast of Taiwan,
0:30:47 > 0:30:50thousands of tonnes of rock and debris were dislodged.
0:31:00 > 0:31:03The Internet cables were out of action for weeks.
0:31:03 > 0:31:05It was an economic disaster.
0:31:08 > 0:31:11The cables didn't stand a chance.
0:31:14 > 0:31:18Help is at hand, but it needs a serious bit of kit.
0:31:20 > 0:31:25Underwater landslides happen all the time.
0:31:25 > 0:31:28The problem is, it's all too common for them to sever the cables
0:31:28 > 0:31:29that support the Internet.
0:31:29 > 0:31:33And that means someone's got to go around fixing them.
0:31:33 > 0:31:35And that's these chaps here.
0:31:46 > 0:31:49I'm on board the Wave Sentinel.
0:31:49 > 0:31:51It's one of a fleet of high-tech vessels
0:31:51 > 0:31:54whose job it is to keep the world connected.
0:31:58 > 0:32:00The hot phone. That rings, we start running.
0:32:00 > 0:32:02- That's it?- That's it.
0:32:02 > 0:32:05- Seriously? Is it on now? - Yeah, it's on.
0:32:05 > 0:32:09- So, if that phone goes... - If that phone goes, I'll get all...
0:32:09 > 0:32:12So this whole thing is on permanent standby,
0:32:12 > 0:32:14- this whole operation? - Permanent standby.
0:32:14 > 0:32:16MOBILE RINGS Excuse me.
0:32:16 > 0:32:17Wave Sentinel captain.
0:32:19 > 0:32:22Contract at 24 hours' notice.
0:32:23 > 0:32:28We're fuelled up, water, provisions, we're ready to go.
0:32:28 > 0:32:31You get that phone call, all of a sudden everyone's in a hurry.
0:32:39 > 0:32:43We get as much information as fast as we can and make a plan.
0:32:44 > 0:32:49And the plan involves heading to the most remote parts of the ocean
0:32:49 > 0:32:53and risking life and limb to fix the cables quickly.
0:32:55 > 0:33:0099% of all Internet business and communication
0:33:00 > 0:33:03that flows between the continents passes through ocean-floor cables.
0:33:05 > 0:33:09They search for the broken cables at depths of up to three miles
0:33:09 > 0:33:11with high-tech, remote-operated vehicles.
0:33:13 > 0:33:18- RADIO:- Back to normal speed. Keep it nice and slow.
0:33:20 > 0:33:24When they find the cable, it's brought back on deck
0:33:24 > 0:33:28and taken to a state-of-the-art operating theatre.
0:33:45 > 0:33:50- So that's what's in there, inside all that cladding, doing the job? - Yes.
0:33:50 > 0:33:54Everything this is about - you, all of your time, the ship,
0:33:54 > 0:33:59the seas, the struggle, the toil - it's in there
0:33:59 > 0:34:02and it's a fraction a thickness of a hair and that's it?
0:34:02 > 0:34:04That's correct.
0:34:04 > 0:34:08How much information is flowing along those?
0:34:08 > 0:34:10Each fibre comes in a pair
0:34:10 > 0:34:13and each fibre pair, at a conservative estimate,
0:34:13 > 0:34:16can transmit 150 million simultaneous phone calls.
0:34:16 > 0:34:18All at the same time.
0:34:18 > 0:34:21It must get very crowded in there.
0:34:21 > 0:34:25It's a very delicate-looking thing to send to the bottom of the sea.
0:34:35 > 0:34:37It's a very fiddly job.
0:34:39 > 0:34:42How the hell do you do this on a moving ship?
0:34:43 > 0:34:46With a great deal of difficulty.
0:34:46 > 0:34:48We're trained professionals.
0:34:50 > 0:34:53Each repair can cost half a million pounds.
0:34:53 > 0:34:58All the big global telecoms companies have these guys on speed dial.
0:35:04 > 0:35:08There are hundreds of landslides each year in the Atlantic.
0:35:08 > 0:35:12It's ships like the Wave Sentinel that keep the World Wide Web connected.
0:35:14 > 0:35:19Having seen a tiny bit of the sea floor myself,
0:35:19 > 0:35:21I now realise just how vast it is,
0:35:21 > 0:35:23yet the only sign of human activity
0:35:23 > 0:35:26is the odd deep-sea sub and some cables.
0:35:26 > 0:35:30Strange how we still think we dominate our planet.
0:35:33 > 0:35:39But of course, the planet is really dominated by the earth machine.
0:35:39 > 0:35:40And that means volcanoes.
0:35:41 > 0:35:4580% of Earth's volcanic activity is hidden underwater
0:35:45 > 0:35:51and some of the volcanoes on the sea floor are big. Very big.
0:35:51 > 0:35:54We think of Everest as the world's tallest mountain.
0:35:54 > 0:35:59But strictly speaking, that accolade belongs to a mountain in the middle of the Pacific Ocean.
0:36:05 > 0:36:08The summit of Mauna Kea volcano on Hawaii
0:36:08 > 0:36:12has grown over two and a half miles above sea level.
0:36:12 > 0:36:17But it's another three and a half miles down to the sea floor.
0:36:17 > 0:36:19And it doesn't stop there.
0:36:19 > 0:36:23Because the island is so heavy, it's sunk into in the sea floor.
0:36:25 > 0:36:29And that means the true base is another five miles further down.
0:36:32 > 0:36:36From top to bottom, Mauna Kea is over 11 miles high.
0:36:36 > 0:36:39That's twice the height of Mount Everest.
0:36:40 > 0:36:44Now we're going to go from the tallest mountain
0:36:44 > 0:36:46to the deepest place on earth.
0:36:49 > 0:36:52So far, we've drained down the oceans down to about three miles,
0:36:52 > 0:36:55which has revealed most of the sea floor.
0:36:59 > 0:37:05But surprisingly, there is more to drain - another four miles, in fact.
0:37:05 > 0:37:09We're about to go to the deepest point on the surface of the earth.
0:37:11 > 0:37:16Normally hidden by water, there is a huge ravine in the earth's crust,
0:37:16 > 0:37:18where two tectonic plates meet.
0:37:22 > 0:37:26And this is it, the Mariana Trench in the western Pacific.
0:37:26 > 0:37:30This baby reaches down nearly seven miles deep.
0:37:43 > 0:37:46At 1,500 miles long and 40 miles wide,
0:37:46 > 0:37:50this massive trench contains the deepest point on earth...
0:37:55 > 0:37:57..the Challenger Deep.
0:38:19 > 0:38:23What's it like down there, nearly seven miles below the surface?
0:38:23 > 0:38:26And why would anyone go there?
0:38:26 > 0:38:30There is a man who knows, first-hand.
0:38:30 > 0:38:3112 men have stood on the moon,
0:38:31 > 0:38:35but only two have been to the deepest place on earth.
0:38:36 > 0:38:38One of them is Don Walsh
0:38:38 > 0:38:42and he's here in San Diego, where it all began.
0:38:48 > 0:38:50Don, then a Navy Lieutenant
0:38:50 > 0:38:53set sail with Swiss oceanographer Jacques Piccard,
0:38:53 > 0:38:56on secret US Navy mission.
0:38:59 > 0:39:03At 6am on 23rd January 1960,
0:39:03 > 0:39:08they climbed into the confined space of the research submarine, Trieste.
0:39:13 > 0:39:19The space inside the cabin was about 35, 38 cubic feet.
0:39:19 > 0:39:24The average household refrigerator has about that same capacity.
0:39:24 > 0:39:26The temperature inside wasn't much different.
0:39:26 > 0:39:28To get an idea, climb into your refrigerator
0:39:28 > 0:39:31for a beer with a six-foot tall friend,
0:39:31 > 0:39:34- close the door and spend nine hours in there?- Nine hours.- Right.
0:39:34 > 0:39:37The Trieste had five-inch-thick walls,
0:39:37 > 0:39:41and the 13-tonne pressure sphere hung under a massive tank
0:39:41 > 0:39:46filled with 22,500 gallons of gasoline for buoyancy.
0:39:49 > 0:39:51The pressure is eight tons per square inch,
0:39:51 > 0:39:55so in an area that size, you'd have eight tons pushing down.
0:39:55 > 0:40:00Total pressure on the cabin was 200,000 tons,
0:40:00 > 0:40:06like 100 WW2 Navy destroyers piled on top of you.
0:40:06 > 0:40:08You will have thought of this, Don,
0:40:08 > 0:40:11if something had gone wrong, what happened?
0:40:11 > 0:40:12It was over.
0:40:13 > 0:40:18The great danger to the mission was the tremendous pressure at these depths.
0:40:18 > 0:40:22At 31,000 feet on our way down, we had a huge bang.
0:40:22 > 0:40:25BANG
0:40:25 > 0:40:27There's a window in the hatch and that had cracked.
0:40:30 > 0:40:33The descent took nearly five hours.
0:40:37 > 0:40:40They'd reached the bottom of the Mariana Trench,
0:40:40 > 0:40:42seven miles below the surface.
0:40:44 > 0:40:47We were in a space ship. It was like visiting another planet.
0:40:47 > 0:40:51Once we'd disconnected from the surface, it was like going through a void of space
0:40:51 > 0:40:55and then landing on an alien planet, it was very much like that.
0:40:55 > 0:40:58After we surfaced, Jacques and I were sitting there,
0:40:58 > 0:41:01waiting for the boats to come fetch us.
0:41:01 > 0:41:05We're talking about this, "When do you think somebody will be back next?"
0:41:05 > 0:41:07We kind of agreed, between one and two years.
0:41:13 > 0:41:15That was a half century ago.
0:41:17 > 0:41:19No-one's been back.
0:41:27 > 0:41:33Don is now the only living man to have been to the deepest place on earth.
0:41:33 > 0:41:36On my little trip into Monterey Bay, I went down a few hundred feet.
0:41:36 > 0:41:42It's extraordinary to think he went down a further six and a half miles.
0:41:42 > 0:41:45Those early glimpses of the deep ocean floor
0:41:45 > 0:41:49suggested very little happened down there.
0:41:49 > 0:41:51But that couldn't have been more wrong.
0:41:51 > 0:41:56We've got to the bottom of the ocean but it's not the end of the journey.
0:41:58 > 0:42:01Because the power of the earth machine beneath the sea floor
0:42:01 > 0:42:05affects the lives of millions of people.
0:42:08 > 0:42:12As the sea floor spreads out from the mid-ocean ridge,
0:42:12 > 0:42:14it eventually collides with the land.
0:42:18 > 0:42:20Massive pressure builds up...
0:42:25 > 0:42:27..until suddenly...
0:42:28 > 0:42:30EXPLOSION
0:42:30 > 0:42:31..it gives.
0:42:50 > 0:42:54This is what happened off the coast of Japan in March 2011.
0:43:01 > 0:43:07An earthquake beneath the sea floor created the devastating tsunami that hit Japan.
0:43:22 > 0:43:27It was a horribly powerful reminder that the whole of the Pacific region
0:43:27 > 0:43:31is very unstable, and earthquakes are frequent.
0:43:31 > 0:43:35Seven years earlier, there was an even bigger earthquake
0:43:35 > 0:43:37and an even more destructive tsunami.
0:43:39 > 0:43:44On 26th December 2004, Indonesia was hit by a devastating earthquake
0:43:44 > 0:43:47that came from beneath the sea floor.
0:43:56 > 0:44:01Just off the coast of Indonesia, the sea bed was ripped open.
0:44:04 > 0:44:10In just six seconds, part of the ocean floor shot up by as much as 20 metres.
0:44:52 > 0:44:54This quake created a powerful tsunami.
0:44:54 > 0:45:00Around South East Asia, more than 200,000 people died.
0:45:17 > 0:45:21The earthquake was so powerful, it shifted the earth on its axis,
0:45:21 > 0:45:25and shortened our days by 2.8 microseconds.
0:45:28 > 0:45:32The quake also moved the North Pole nearly an inch to the east.
0:45:42 > 0:45:47Fortunately, most undersea quakes go unnoticed by you and me.
0:45:47 > 0:45:51But scientists always record the effect they have on earth.
0:45:51 > 0:45:55Normally we can't hear them, but thanks to a clever bit of technology,
0:45:55 > 0:46:01we can hear what the Indonesian undersea earthquake sounded like.
0:46:01 > 0:46:04DISTANT RUMBLING
0:46:09 > 0:46:13The Earth literally rang like a bell for weeks.
0:46:18 > 0:46:23The enormous power of the devastating Indonesian earthquake
0:46:23 > 0:46:28is evidence of a much bigger process that starts on the ocean floor.
0:46:29 > 0:46:34As the heavier rock of the sea floor bumps up against the land,
0:46:34 > 0:46:38it has nowhere to go but down.
0:46:47 > 0:46:50It's a process called subduction.
0:46:52 > 0:46:57This collision between the sea floor and the land creates enormous pressure.
0:46:59 > 0:47:04As it falls, the rock begins to melt.
0:47:04 > 0:47:07The heat and pressure is so great that some of this molten rock
0:47:07 > 0:47:11escapes upwards through cracks in the land above.
0:47:11 > 0:47:16When the lava reaches the surface, the results are spectacular.
0:47:16 > 0:47:22This is engineering on a truly global scale.
0:47:24 > 0:47:26As the sea floor is pushed under the land,
0:47:26 > 0:47:30the melting rock has created a chain of over 200 volcanoes
0:47:30 > 0:47:33along the west coast of South America...
0:47:34 > 0:47:40..and another 50 active volcanoes further up the coast to the USA and Alaska.
0:47:45 > 0:47:49Across and down around the coast of Russia, Japan and China,
0:47:49 > 0:47:50there are hundreds more.
0:47:53 > 0:47:59From back here, they look like rivets holding the planet together.
0:48:05 > 0:48:11This line of coastal volcanoes is known as the Pacific Ring of Fire.
0:48:29 > 0:48:34These volcanoes mark the zone where the sea floor has been pushed down beneath the land.
0:48:34 > 0:48:38When it melts, the searing heat and build-up of pressure
0:48:38 > 0:48:42causes some of the most destructive eruptions ever seen.
0:48:48 > 0:48:53The most volcanically active of these islands is Java in Indonesia,
0:48:53 > 0:48:57with 42 volcanoes in a row.
0:48:58 > 0:49:01I've always thought of volcanoes as purely destructive,
0:49:01 > 0:49:03but, in fact, they bring valuable minerals
0:49:03 > 0:49:06and vital gases to the surface.
0:49:06 > 0:49:09At the Kawah Ijen volcano in Indonesia,
0:49:09 > 0:49:13you can witness one of the most extraordinary sights created by the earth's machine.
0:49:34 > 0:49:40This haunting spectacle is liquid sulphur burning within the crater of the volcano.
0:50:04 > 0:50:08Sulphur is one of the most important chemicals for industry,
0:50:08 > 0:50:10but it's also is one of the key minerals needed
0:50:10 > 0:50:12for all life on earth.
0:50:14 > 0:50:18These liquid rivers of burning sulphur are fed by the sea floor
0:50:18 > 0:50:23melting 60 miles below the land.
0:50:39 > 0:50:44In Kawah Ijen, we can see first-hand how the earth's machine
0:50:44 > 0:50:46produces these valuable chemicals.
0:50:48 > 0:50:54In the craters of volcanoes like this, we can get our hands on raw sulphur.
0:50:54 > 0:50:58The poisonous gases sulphur gives off make this place
0:50:58 > 0:51:02one of the most toxic environments on the planet.
0:51:13 > 0:51:17Every day, hundreds of miners descend into these fumes
0:51:17 > 0:51:20to bring out solid sulphur by hand.
0:51:30 > 0:51:34These gases are so corrosive that the men can only spend
0:51:34 > 0:51:37- a brief time in the crater. - MEN COUGH
0:51:37 > 0:51:40No wonder they have a short life expectancy.
0:52:07 > 0:52:12Liquid sulphur pours out of the ground at 600 degrees centigrade...
0:52:17 > 0:52:19..then solidifies.
0:52:24 > 0:52:28Every day, the miners bring out tonnes of the yellow sulphur...
0:52:28 > 0:52:31the hard way!
0:52:41 > 0:52:45Sulphur is used in everything from medicines to fertilisers,
0:52:45 > 0:52:49vulcanising rubber and even for making your sugar that perfect white.
0:53:00 > 0:53:05Volcanoes bring other vital minerals to the surface
0:53:05 > 0:53:10that enrich the soil and release gases that help create the air we breathe.
0:53:14 > 0:53:18Volcanoes are an essential part of the earth's machine.
0:53:26 > 0:53:28But our journey isn't over yet.
0:53:28 > 0:53:30We're about to find out what happens to the sea floor
0:53:30 > 0:53:32when it plunges under the land.
0:53:35 > 0:53:38Having been forced down under the land,
0:53:38 > 0:53:42some of the slabs of melting sea floor continue to fall,
0:53:42 > 0:53:45their weight pulling more sea floor behind them.
0:53:47 > 0:53:49Beneath the mantle is the core.
0:53:52 > 0:53:57The core is the energy source that drives the earth's machine.
0:54:01 > 0:54:03The core is even hotter than the mantle
0:54:03 > 0:54:06and, as the descending sea floor reaches its outer surface,
0:54:06 > 0:54:09it's superheated and rises back up
0:54:09 > 0:54:12in vast plumes towards the surface.
0:54:17 > 0:54:20It's one continuous cycle -
0:54:20 > 0:54:22one that takes millions of years.
0:54:22 > 0:54:26It really is the most amazing piece of engineering.
0:54:29 > 0:54:33And it's all driven by the core of the earth machine.
0:54:37 > 0:54:42So far we've drained the ocean from the coast to the deepest point on earth.
0:54:42 > 0:54:45We've followed the journey of the sea bed
0:54:45 > 0:54:49from its birth at the mid-ocean ridge to where it collides with the land.
0:54:49 > 0:54:51We've seen the enormous forces
0:54:51 > 0:54:54that drive the whole cycle of the sea floor,
0:54:54 > 0:54:57yet we've overlooked the water itself.
0:54:59 > 0:55:05Without it, there would be no life on earth.
0:55:19 > 0:55:25So what would happen if the earth really did lose all its oceans?
0:55:25 > 0:55:30Seriously scary things would happen, that's what!
0:55:31 > 0:55:34Without the weight of the oceans, the mid-ocean ridge
0:55:34 > 0:55:37would erupt violently, the planet would unzip
0:55:37 > 0:55:40around the mid-ocean ridge.
0:55:43 > 0:55:48Vast sheets of lava would explode into the sky.
0:55:50 > 0:55:54Without the weight of water to support their sides,
0:55:54 > 0:55:56the continental shelves would collapse.
0:56:00 > 0:56:04Mud slides and dirt avalanches bigger than anything seen before
0:56:04 > 0:56:07would be unleashed.
0:56:10 > 0:56:13Massive pockets of methane gas would explode.
0:56:16 > 0:56:20All this would cause hundreds of devastating earthquakes.
0:56:25 > 0:56:28And with no water, there would be no weather,
0:56:28 > 0:56:30no rain.
0:56:30 > 0:56:33The entire planet would become a desert.
0:56:33 > 0:56:37There would be nothing left alive.
0:56:45 > 0:56:47Luckily, that's not going to happen.
0:56:47 > 0:56:50So let's put it all back again.
0:56:54 > 0:56:56We've seen how the earth works.
0:56:56 > 0:56:59How the machine beneath the sea floor creates
0:56:59 > 0:57:02the biggest geological features on the planet
0:57:02 > 0:57:05and also drives the movement of the sea floor
0:57:05 > 0:57:10to release minerals and gases so vital to life on earth.
0:57:20 > 0:57:25The oceans are one of the most beautiful sights on our planet.
0:57:25 > 0:57:28Hidden beneath the waves are some extraordinary processes
0:57:28 > 0:57:33without which life on earth simply could not exist.
0:58:09 > 0:58:11Subtitles by Red Bee Media Ltd
0:58:11 > 0:58:13E-mail subtitling@bbc.co.uk