The Bottom of the Ocean Richard Hammond's Journey To...


The Bottom of the Ocean

What lies at the bottom of the oceans? What would happen if the planet lost its oceans? Richard Hammond is going to drain the oceans to find out.


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Transcript


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Our planet is unique.

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An extraordinary piece of engineering,

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over four and a half billion years old.

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And to show you how it works, we've created something rather special.

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We've collected the latest information

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from scientists around the world.

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We've added satellite maps, sonar and radar images

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and we've brought it all together to make this.

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We've created a virtual planet earth.

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In here we can dismantle the earth's machinery piece by piece,

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and see how an enormous energy source,

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buried deep within the planet, shapes our world,

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up here on the surface.

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Many of the most powerful effects happen on the ocean floor.

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And it was the movement of the sea bed 80 miles off the coast of Japan

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that triggered the tsunami in March 2011.

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So to reveal how the earth machine works,

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we need to drain the oceans.

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Every now and then, we get a glimpse of what's below the surface.

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We can shine a light or we can go down in a sub.

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But it's hard to get the whole picture.

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The more I think about the sea beneath me,

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the more questions I have.

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What if we could drain the oceans?

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What would we see? What surprises are down there?

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And what dangers lurk?

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-Have you ever had anybody panic completely?

-Yes.

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Why does more volcanic activity take place underwater than on land?

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Seeing as I'm already dressed...

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What's one of the biggest underwater threats to the Internet...

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-If that phone goes...?

-If that phone goes, I'll get all...

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..and our lives?

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How can chimneys spout gold

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and be home to snails made of metal?

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And why have more men been to the moon

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than to the deepest point in our oceans?

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We've combined the latest scientific data

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with some very clever computer software

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to show you the wonders of the deep ocean.

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Wonders created by a machine hidden beneath the sea floor.

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A machine so powerful, it not only affects all our lives,

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it drives the planet.

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We're going to take you on a journey to the bottom of the sea

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and beyond even that.

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On Friday 11th March, 2011...

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..a devastating tsunami crashed into the coast of Japan.

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In some places, the waves reached 98 feet high.

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It was caused by a powerful earthquake

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that measured nine on the Richter scale.

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This was the worst earthquake to hit Japan for over 100 years.

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The death toll was at least 25,000.

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This was the earth machine in action on an awesome scale.

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The source of this devastation was 80 miles offshore

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and deep below the surface of the ocean.

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Oh, yeah, that's me. I'm doing that.

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I did that then.

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In order to show you how the earth machine works

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and see how it affects us, we need first to get down to the ocean floor.

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And we start, I'm delighted to say, down there.

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The English Channel.

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I know it may not be the most obvious place

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to start a journey to the bottom of the sea, but bear with me.

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The waters between Dover and Calais are about 40 metres deep,

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which, in sea terms, is pretty shallow.

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That's because this part of the seabed is just flooded land.

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9,000 years ago you could walk -

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give or take the odd river - from England to France.

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Now we can reveal what that looks like today.

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So, let's drain it and have a look.

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With a bit of computer technology, we can do in seconds

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what it takes the earth machine thousands of years to do.

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And, well, frankly, the English Channel is a bit of a mess.

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From up here, it looks like a scrap yard.

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There are over 8,000 shipwrecks in this stretch of water alone.

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What the Channel does show us is that, over time,

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the boundaries of the land we live on can change.

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The earth machine has such power

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that it continually changes the surface of the earth.

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The earth's surface is made up of a series of giant tectonic plates

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which are constantly on the move.

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Over time, as the continents have shifted

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and sea levels rise and fall,

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what was once land has sunk underwater.

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As we begin to drain the ocean, the first thing we see

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is that the continents we live on extend far out from the shore.

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In some places, hundreds of miles.

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This submerged land makes up the continental shelf.

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The continental shelf has become one of the most valuable places on earth.

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And there's a very good reason for this.

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If we plot all the oil and gas platforms found out at sea,

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it becomes clear that almost all of these

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are concentrated on the continental shelf.

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For millions of years, dead sea creatures

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and sediment from the land have rained down on the sea bed.

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With time, pressure and heat, this debris turns into oil

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and this has made the shelf immensely valuable.

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Today, these large oil and gas fields

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help fuel our cars...

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..boats...

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and jets.

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As we drain the water from the seas and leave the shore far behind,

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we come to the edge of the continental land mass,

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where the sea bed slopes steeply down to the ocean floor.

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The edge of the continental shelf is often unstable and easily eroded.

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It's here that we find some of the shelf's biggest features.

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Deep canyons.

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To get an idea of the scale of these underwater canyons,

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think the Grand Canyon in the USA.

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It's one mile deep, 18 miles wide and 277 miles long.

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Yet the canyons on the continental shelf can be even larger.

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Anyone can visit the Grand Canyon. I've done it myself.

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But to see these underwater canyons is a much more serious challenge.

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This is Monterey Bay, California,

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and just out there is one of the wonders of the ocean.

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To show you it, I need a pretty specialised vehicle. This.

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Oh, yeah.

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'It may look like a glass bubble but this little baby

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'is actually a two-man sub that can dive nearly one mile beneath the surface.

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'It's one of the world's most technologically advanced glass bubbles.

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'And it needs to be,

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'because to get to the bottom of an undersea canyon is a deep, dark

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'and potentially dangerous dive.'

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You've got the fire extinguisher, mask, oxygen system. And that's it.

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Our visibility is good.

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'Now, which way is the ocean?'

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'Luckily, I'm in the capable hands of pilot Mike Caplehorn.'

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'Monterey Bay Canyon begins just a few hundred metres off the shore,

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'so we don't have to go out too far.'

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I'm steering 203, south.

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Roger, stand by.

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'The support diver unhooks us from the boat

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'and we'll then head down into the abyss.'

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This is where it's going to come up the window

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and, I presume, feel pretty unnerving.

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-Mike, have you ever had anyone panic completely?

-Yes.

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OK...

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'I wasn't scared, I was just sweating...cos it's warm in there.'

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My main vents are about to be closed.

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'High speed with four wheels on land,

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'not usually a problem for me. But trapped in here,

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'heading vertically down, it was a BIT scary.'

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There goes the sun.

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-That's it. We are now, just, officially underwater.

-Yeah.

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I'm trying very hard to be cool about this, but arrrhhh!

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OK, we're commencing our descent.

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Comm is good and we are tracking you.

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O2 is 19.2...

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'The Monterey Canyon is deep.

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'From the surface of the ocean to the bottom of the canyon, it's over two miles.'

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Yeah, Deep Sea, Deep Sea...

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Heading 160.

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'We're now more than 300 feet down,

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'rapidly descending into the mouth of the canyon.'

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There's the monster.

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Two miles deep from the surface of the sea

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down to the bottom of the deepest part.

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That's 3km that way.

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'You'd think the water down here would be crystal clear,

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'but it's like a snow storm.

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'Much of this sediment has been washed off the land

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'and funnelled into the deep,

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'a process that helps carve out the canyon.'

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-Look at the jellyfish. See them?

-Where, where? Oh, God!

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-That is enormous!

-It is very big.

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OK, I'm going a little bit deeper, see if we can get more vertical.

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'The sun's rays can't penetrate this far down.

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'We're now 700 feet down and can only see as far as our lights can shine.

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'It's cold, dark and just a bit intimidating.

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'This is where creatures glow in the dark.

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'I'm in the realm of aliens.'

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That one flashed neon when it hit the light.

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Lit up.

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'So far, so good,

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'and I was just about getting used to this deep ocean business,

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-'when, all of a sudden...'

-CRACK

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What was that?

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That was just a crack in the glass, nothing to worry about.

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That's not a sound I want to hear! Don't ever say that to me again!

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OK, we'll turn around and head for the wall.

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'Yeah, I hope Mike's a better pilot that he is comedian.

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'Because somewhere up in front of us is the wall of the canyon.

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'The visibility is getting worse.

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'This is where it gets tense.'

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If you go forward 200 south, 200 south.

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-That is it.

-That's the wall?

-That's the wall.

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Look at that. That really is the walls of a canyon.

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Mike, well done!

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'Mike tells me the walls extend for hundreds of feet below

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'and for miles either side but with the poor visibility

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'and the fact we can't go any deeper,

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'it's time to head back to the surface.'

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Oh, land! It's there.

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It might not be the most original thought

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but that really is another world down there.

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And bobbing about back up on the surface, waiting to be picked up,

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again, it's not the most original thought,

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but I felt like we were two returning astronauts in our capsule, all sealed in.

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I need a cup of tea more than anything else in the whole world.

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I've been lucky to get a glimpse of the canyon

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but there's only one way to see the whole thing.

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With our virtual earth, we can drain all the water from Monterey Bay Canyon.

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It took around ten million years to carve this canyon

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into the side of the continental shelf.

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But if you think THAT's big, just hold on.

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A few thousand miles northwest of California,

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just off the coast of Russia,

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there's a canyon that makes Monterey look like a teacup.

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The largest canyon on the planet is the Zhemchug.

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It's nearly two miles deep at its deepest point

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and 144 miles long and 62 miles wide.

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Of course, it's normally hidden by the Pacific Ocean

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but the Zhemchug is so wide it's impossible to see from one side to the other

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unless you are above the curvature of the Earth.

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So far on our journey to the bottom of the sea,

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we've drained the water from the beaches to the edge of the continental shelf.

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We've drained the water from the cliffs and canyons

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and now we've reached the floor of the deep ocean.

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For the first time, we can see direct evidence

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of the earth machine and how it affects this part of the sea floor.

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It's called the abyssal plain

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and it covers over half the planet's surface.

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For years, it was thought to be flat and lifeless,

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but in the middle of the Atlantic, you find one of the biggest geological features on the planet.

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It is one of the most important parts of the earth machine.

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This huge mountain range is called the Mid-Atlantic Ridge

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and it's one of the largest and most active geological structures

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in the entire solar system.

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It's part of a vast tear in the planet's surface -

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a single line of underwater mountains and volcanoes

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that runs for over 40,000 miles around the planet.

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At the mid-ocean ridge, lava forces its way up from below.

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It's supplied by the mantle, a searing-hot layer below the crust.

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This tear in the crust shows the power

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of the machine that drives planet earth.

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As the lava flows out,

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it spreads away from the centre of the ridge and cools.

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This pushes the whole sea floor ahead of it

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and creates incredible stresses and strains.

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This pressure triggers earthquakes and landslides,

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makes deep valleys and huge undersea mountains.

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This continuous process produces a square mile of new rock every year.

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If we travel north, up here we come to a place

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where the vast volcano range rises out of the water,

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creating an island like no other.

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Iceland.

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Iceland is the only place in the world where the mid-ocean ridge

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rises above the waves, exposing over 100 active volcanoes.

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At one time, this whole landscape would have been underwater.

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It's the closest I'll get to the ocean floor.

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Iceland gives me the chance to take a look

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at the mid-ocean ridge from the inside.

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That is Lake Thingvellir

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and this crack is part of the Mid-Atlantic Ridge.

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It's known locally as Silfra and it's considered

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one of the most beautiful and spectacular dives in the world.

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And seeing as I'm already dressed...

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'You can swim through the gap

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'between the two halves of the mid-ocean ridge.

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'They're moving apart by about an inch a year.'

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On this side, the United States.

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On that side, Europe.

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And they're just metres apart.

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'A couple of million years ago, there would have been lava pouring up through this crack.

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'Now it's cooled and solidified, it's left an incredible opportunity

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'for us to see inside the mid-ocean ridge.'

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Because the ground in Iceland is very thin -

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in some places only a few miles deep -

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you can see other effects caused by the volcanic machine below.

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The thermal power of the earth is evident everywhere here.

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This is one of Iceland's many famous geysers,

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and the way it works is actually pretty simple.

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It's like switching on a giant, instantly boiling kettle every few minutes.

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The rocks down there are at about 200 degrees centigrade.

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When water enters an underground chamber about 60 feet down,

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it's boiled instantly, so it expands hugely,

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it explodes into steam and fires out of the hole,

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creating this magnificent spectacle.

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Surprisingly, geysers exist all along the mid-ocean ridge.

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One mile down, on the ocean floor, they look like this.

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They're called black smokers

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and they were only discovered about 30 years ago.

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Superheated water laced with precious minerals -

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gold, silver and iron - races up from the volcanic rocks below.

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As they hit the cold sea water, the minerals turn black.

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They then solidify into chimneys that can grow up to 180 feet high.

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The chimneys would be worth a fortune

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but right now they're just too difficult to mine.

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But scientists have recently discovered a little chap

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who's been mining the black smokers for years.

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A metal snail.

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This snail makes its shell and the scales on its foot

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from the metals in the water around it.

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The scaly-foot is the most extraordinary thing I've found.

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These scaly-foot snails were discovered nearly two miles down

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in the ocean by Professor Cindy Van Dover.

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We were sampling the large common snails,

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and in the handful of snails that we brought to the surface,

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we discovered these small, scaly-foot snails.

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We wondered for a couple of weeks, what could they be? We didn't know.

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There is no other known snail that has a metal-fortified shell.

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Even in the animal kingdom, we don't know of anything else that has a metal-fortified shell.

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The animals have spent evolutionary time

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honing the composition of their shell

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to make it deflect predators, to make it strong.

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So, it's like having armour.

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What a weird little fellow.

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Each time scientists visit these volcanic worlds,

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over half the animals they find are unknown to science.

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Here's this little animal that sits in this warm water that's coming out,

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that's metal-rich, and it's sitting there mining these metals.

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That is extraordinary.

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Super snails and precious metals are just a tiny part of the riches

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produced by the volcanic machine below.

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A machine that has a much more destructive side.

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When the new sea floor spreads out from the mid-ocean ridge,

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the sea floor buckles, and causes massive undersea movements and landslides.

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Although these happen miles beneath the ocean, they can affect us all.

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You might not know this, but pretty much all Internet traffic

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is carried between the continents by undersea cables.

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In December 2006, nine fibre optic cables

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between Taiwan and the Philippines suddenly went dead.

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Computers across Asia crashed.

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Engineers soon discovered that the cables had been severed.

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But...by what?

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Let's take a look beneath the waves.

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Sediment collects in huge quantities

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on the edge of underwater ledges and canyons.

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Earthquakes then trigger underwater landslides.

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On this occasion, just off the coast of Taiwan,

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thousands of tonnes of rock and debris were dislodged.

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The Internet cables were out of action for weeks.

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It was an economic disaster.

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The cables didn't stand a chance.

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Help is at hand, but it needs a serious bit of kit.

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Underwater landslides happen all the time.

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The problem is, it's all too common for them to sever the cables

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that support the Internet.

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And that means someone's got to go around fixing them.

0:31:290:31:33

And that's these chaps here.

0:31:330:31:35

I'm on board the Wave Sentinel.

0:31:460:31:49

It's one of a fleet of high-tech vessels

0:31:490:31:51

whose job it is to keep the world connected.

0:31:510:31:54

The hot phone. That rings, we start running.

0:31:580:32:00

-That's it?

-That's it.

0:32:000:32:02

-Seriously? Is it on now?

-Yeah, it's on.

0:32:020:32:05

-So, if that phone goes...

-If that phone goes, I'll get all...

0:32:050:32:09

So this whole thing is on permanent standby,

0:32:090:32:12

-this whole operation?

-Permanent standby.

0:32:120:32:14

MOBILE RINGS Excuse me.

0:32:140:32:16

Wave Sentinel captain.

0:32:160:32:17

Contract at 24 hours' notice.

0:32:190:32:22

We're fuelled up, water, provisions, we're ready to go.

0:32:230:32:28

You get that phone call, all of a sudden everyone's in a hurry.

0:32:280:32:31

We get as much information as fast as we can and make a plan.

0:32:390:32:43

And the plan involves heading to the most remote parts of the ocean

0:32:440:32:49

and risking life and limb to fix the cables quickly.

0:32:490:32:53

99% of all Internet business and communication

0:32:550:33:00

that flows between the continents passes through ocean-floor cables.

0:33:000:33:03

They search for the broken cables at depths of up to three miles

0:33:050:33:09

with high-tech, remote-operated vehicles.

0:33:090:33:11

-RADIO:

-Back to normal speed. Keep it nice and slow.

0:33:130:33:18

When they find the cable, it's brought back on deck

0:33:200:33:24

and taken to a state-of-the-art operating theatre.

0:33:240:33:28

-So that's what's in there, inside all that cladding, doing the job?

-Yes.

0:33:450:33:50

Everything this is about - you, all of your time, the ship,

0:33:500:33:54

the seas, the struggle, the toil - it's in there

0:33:540:33:59

and it's a fraction a thickness of a hair and that's it?

0:33:590:34:02

That's correct.

0:34:020:34:04

How much information is flowing along those?

0:34:040:34:08

Each fibre comes in a pair

0:34:080:34:10

and each fibre pair, at a conservative estimate,

0:34:100:34:13

can transmit 150 million simultaneous phone calls.

0:34:130:34:16

All at the same time.

0:34:160:34:18

It must get very crowded in there.

0:34:180:34:21

It's a very delicate-looking thing to send to the bottom of the sea.

0:34:210:34:25

It's a very fiddly job.

0:34:350:34:37

How the hell do you do this on a moving ship?

0:34:390:34:42

With a great deal of difficulty.

0:34:430:34:46

We're trained professionals.

0:34:460:34:48

Each repair can cost half a million pounds.

0:34:500:34:53

All the big global telecoms companies have these guys on speed dial.

0:34:530:34:58

There are hundreds of landslides each year in the Atlantic.

0:35:040:35:08

It's ships like the Wave Sentinel that keep the World Wide Web connected.

0:35:080:35:12

Having seen a tiny bit of the sea floor myself,

0:35:140:35:19

I now realise just how vast it is,

0:35:190:35:21

yet the only sign of human activity

0:35:210:35:23

is the odd deep-sea sub and some cables.

0:35:230:35:26

Strange how we still think we dominate our planet.

0:35:260:35:30

But of course, the planet is really dominated by the earth machine.

0:35:330:35:39

And that means volcanoes.

0:35:390:35:40

80% of Earth's volcanic activity is hidden underwater

0:35:410:35:45

and some of the volcanoes on the sea floor are big. Very big.

0:35:450:35:51

We think of Everest as the world's tallest mountain.

0:35:510:35:54

But strictly speaking, that accolade belongs to a mountain in the middle of the Pacific Ocean.

0:35:540:35:59

The summit of Mauna Kea volcano on Hawaii

0:36:050:36:08

has grown over two and a half miles above sea level.

0:36:080:36:12

But it's another three and a half miles down to the sea floor.

0:36:120:36:17

And it doesn't stop there.

0:36:170:36:19

Because the island is so heavy, it's sunk into in the sea floor.

0:36:190:36:23

And that means the true base is another five miles further down.

0:36:250:36:29

From top to bottom, Mauna Kea is over 11 miles high.

0:36:320:36:36

That's twice the height of Mount Everest.

0:36:360:36:39

Now we're going to go from the tallest mountain

0:36:400:36:44

to the deepest place on earth.

0:36:440:36:46

So far, we've drained down the oceans down to about three miles,

0:36:490:36:52

which has revealed most of the sea floor.

0:36:520:36:55

But surprisingly, there is more to drain - another four miles, in fact.

0:36:590:37:05

We're about to go to the deepest point on the surface of the earth.

0:37:050:37:09

Normally hidden by water, there is a huge ravine in the earth's crust,

0:37:110:37:16

where two tectonic plates meet.

0:37:160:37:18

And this is it, the Mariana Trench in the western Pacific.

0:37:220:37:26

This baby reaches down nearly seven miles deep.

0:37:260:37:30

At 1,500 miles long and 40 miles wide,

0:37:430:37:46

this massive trench contains the deepest point on earth...

0:37:460:37:50

..the Challenger Deep.

0:37:550:37:57

What's it like down there, nearly seven miles below the surface?

0:38:190:38:23

And why would anyone go there?

0:38:230:38:26

There is a man who knows, first-hand.

0:38:260:38:30

12 men have stood on the moon,

0:38:300:38:31

but only two have been to the deepest place on earth.

0:38:310:38:35

One of them is Don Walsh

0:38:360:38:38

and he's here in San Diego, where it all began.

0:38:380:38:42

Don, then a Navy Lieutenant

0:38:480:38:50

set sail with Swiss oceanographer Jacques Piccard,

0:38:500:38:53

on secret US Navy mission.

0:38:530:38:56

At 6am on 23rd January 1960,

0:38:590:39:03

they climbed into the confined space of the research submarine, Trieste.

0:39:030:39:08

The space inside the cabin was about 35, 38 cubic feet.

0:39:130:39:19

The average household refrigerator has about that same capacity.

0:39:190:39:24

The temperature inside wasn't much different.

0:39:240:39:26

To get an idea, climb into your refrigerator

0:39:260:39:28

for a beer with a six-foot tall friend,

0:39:280:39:31

-close the door and spend nine hours in there?

-Nine hours.

-Right.

0:39:310:39:34

The Trieste had five-inch-thick walls,

0:39:340:39:37

and the 13-tonne pressure sphere hung under a massive tank

0:39:370:39:41

filled with 22,500 gallons of gasoline for buoyancy.

0:39:410:39:46

The pressure is eight tons per square inch,

0:39:490:39:51

so in an area that size, you'd have eight tons pushing down.

0:39:510:39:55

Total pressure on the cabin was 200,000 tons,

0:39:550:40:00

like 100 WW2 Navy destroyers piled on top of you.

0:40:000:40:06

You will have thought of this, Don,

0:40:060:40:08

if something had gone wrong, what happened?

0:40:080:40:11

It was over.

0:40:110:40:12

The great danger to the mission was the tremendous pressure at these depths.

0:40:130:40:18

At 31,000 feet on our way down, we had a huge bang.

0:40:180:40:22

BANG

0:40:220:40:25

There's a window in the hatch and that had cracked.

0:40:250:40:27

The descent took nearly five hours.

0:40:300:40:33

They'd reached the bottom of the Mariana Trench,

0:40:370:40:40

seven miles below the surface.

0:40:400:40:42

We were in a space ship. It was like visiting another planet.

0:40:440:40:47

Once we'd disconnected from the surface, it was like going through a void of space

0:40:470:40:51

and then landing on an alien planet, it was very much like that.

0:40:510:40:55

After we surfaced, Jacques and I were sitting there,

0:40:550:40:58

waiting for the boats to come fetch us.

0:40:580:41:01

We're talking about this, "When do you think somebody will be back next?"

0:41:010:41:05

We kind of agreed, between one and two years.

0:41:050:41:07

That was a half century ago.

0:41:130:41:15

No-one's been back.

0:41:170:41:19

Don is now the only living man to have been to the deepest place on earth.

0:41:270:41:33

On my little trip into Monterey Bay, I went down a few hundred feet.

0:41:330:41:36

It's extraordinary to think he went down a further six and a half miles.

0:41:360:41:42

Those early glimpses of the deep ocean floor

0:41:420:41:45

suggested very little happened down there.

0:41:450:41:49

But that couldn't have been more wrong.

0:41:490:41:51

We've got to the bottom of the ocean but it's not the end of the journey.

0:41:510:41:56

Because the power of the earth machine beneath the sea floor

0:41:580:42:01

affects the lives of millions of people.

0:42:010:42:05

As the sea floor spreads out from the mid-ocean ridge,

0:42:080:42:12

it eventually collides with the land.

0:42:120:42:14

Massive pressure builds up...

0:42:180:42:20

..until suddenly...

0:42:250:42:27

EXPLOSION

0:42:280:42:30

..it gives.

0:42:300:42:31

This is what happened off the coast of Japan in March 2011.

0:42:500:42:54

An earthquake beneath the sea floor created the devastating tsunami that hit Japan.

0:43:010:43:07

It was a horribly powerful reminder that the whole of the Pacific region

0:43:220:43:27

is very unstable, and earthquakes are frequent.

0:43:270:43:31

Seven years earlier, there was an even bigger earthquake

0:43:310:43:35

and an even more destructive tsunami.

0:43:350:43:37

On 26th December 2004, Indonesia was hit by a devastating earthquake

0:43:390:43:44

that came from beneath the sea floor.

0:43:440:43:47

Just off the coast of Indonesia, the sea bed was ripped open.

0:43:560:44:01

In just six seconds, part of the ocean floor shot up by as much as 20 metres.

0:44:040:44:10

This quake created a powerful tsunami.

0:44:520:44:54

Around South East Asia, more than 200,000 people died.

0:44:540:45:00

The earthquake was so powerful, it shifted the earth on its axis,

0:45:170:45:21

and shortened our days by 2.8 microseconds.

0:45:210:45:25

The quake also moved the North Pole nearly an inch to the east.

0:45:280:45:32

Fortunately, most undersea quakes go unnoticed by you and me.

0:45:420:45:47

But scientists always record the effect they have on earth.

0:45:470:45:51

Normally we can't hear them, but thanks to a clever bit of technology,

0:45:510:45:55

we can hear what the Indonesian undersea earthquake sounded like.

0:45:550:46:01

DISTANT RUMBLING

0:46:010:46:04

The Earth literally rang like a bell for weeks.

0:46:090:46:13

The enormous power of the devastating Indonesian earthquake

0:46:180:46:23

is evidence of a much bigger process that starts on the ocean floor.

0:46:230:46:28

As the heavier rock of the sea floor bumps up against the land,

0:46:290:46:34

it has nowhere to go but down.

0:46:340:46:38

It's a process called subduction.

0:46:470:46:50

This collision between the sea floor and the land creates enormous pressure.

0:46:520:46:57

As it falls, the rock begins to melt.

0:46:590:47:04

The heat and pressure is so great that some of this molten rock

0:47:040:47:07

escapes upwards through cracks in the land above.

0:47:070:47:11

When the lava reaches the surface, the results are spectacular.

0:47:110:47:16

This is engineering on a truly global scale.

0:47:160:47:22

As the sea floor is pushed under the land,

0:47:240:47:26

the melting rock has created a chain of over 200 volcanoes

0:47:260:47:30

along the west coast of South America...

0:47:300:47:33

..and another 50 active volcanoes further up the coast to the USA and Alaska.

0:47:340:47:40

Across and down around the coast of Russia, Japan and China,

0:47:450:47:49

there are hundreds more.

0:47:490:47:50

From back here, they look like rivets holding the planet together.

0:47:530:47:59

This line of coastal volcanoes is known as the Pacific Ring of Fire.

0:48:050:48:11

These volcanoes mark the zone where the sea floor has been pushed down beneath the land.

0:48:290:48:34

When it melts, the searing heat and build-up of pressure

0:48:340:48:38

causes some of the most destructive eruptions ever seen.

0:48:380:48:42

The most volcanically active of these islands is Java in Indonesia,

0:48:480:48:53

with 42 volcanoes in a row.

0:48:530:48:57

I've always thought of volcanoes as purely destructive,

0:48:580:49:01

but, in fact, they bring valuable minerals

0:49:010:49:03

and vital gases to the surface.

0:49:030:49:06

At the Kawah Ijen volcano in Indonesia,

0:49:060:49:09

you can witness one of the most extraordinary sights created by the earth's machine.

0:49:090:49:13

This haunting spectacle is liquid sulphur burning within the crater of the volcano.

0:49:340:49:40

Sulphur is one of the most important chemicals for industry,

0:50:040:50:08

but it's also is one of the key minerals needed

0:50:080:50:10

for all life on earth.

0:50:100:50:12

These liquid rivers of burning sulphur are fed by the sea floor

0:50:140:50:18

melting 60 miles below the land.

0:50:180:50:23

In Kawah Ijen, we can see first-hand how the earth's machine

0:50:390:50:44

produces these valuable chemicals.

0:50:440:50:46

In the craters of volcanoes like this, we can get our hands on raw sulphur.

0:50:480:50:54

The poisonous gases sulphur gives off make this place

0:50:540:50:58

one of the most toxic environments on the planet.

0:50:580:51:02

Every day, hundreds of miners descend into these fumes

0:51:130:51:17

to bring out solid sulphur by hand.

0:51:170:51:20

These gases are so corrosive that the men can only spend

0:51:300:51:34

-a brief time in the crater.

-MEN COUGH

0:51:340:51:37

No wonder they have a short life expectancy.

0:51:370:51:40

Liquid sulphur pours out of the ground at 600 degrees centigrade...

0:52:070:52:12

..then solidifies.

0:52:170:52:19

Every day, the miners bring out tonnes of the yellow sulphur...

0:52:240:52:28

the hard way!

0:52:280:52:31

Sulphur is used in everything from medicines to fertilisers,

0:52:410:52:45

vulcanising rubber and even for making your sugar that perfect white.

0:52:450:52:49

Volcanoes bring other vital minerals to the surface

0:53:000:53:05

that enrich the soil and release gases that help create the air we breathe.

0:53:050:53:10

Volcanoes are an essential part of the earth's machine.

0:53:140:53:18

But our journey isn't over yet.

0:53:260:53:28

We're about to find out what happens to the sea floor

0:53:280:53:30

when it plunges under the land.

0:53:300:53:32

Having been forced down under the land,

0:53:350:53:38

some of the slabs of melting sea floor continue to fall,

0:53:380:53:42

their weight pulling more sea floor behind them.

0:53:420:53:45

Beneath the mantle is the core.

0:53:470:53:49

The core is the energy source that drives the earth's machine.

0:53:520:53:57

The core is even hotter than the mantle

0:54:010:54:03

and, as the descending sea floor reaches its outer surface,

0:54:030:54:06

it's superheated and rises back up

0:54:060:54:09

in vast plumes towards the surface.

0:54:090:54:12

It's one continuous cycle -

0:54:170:54:20

one that takes millions of years.

0:54:200:54:22

It really is the most amazing piece of engineering.

0:54:220:54:26

And it's all driven by the core of the earth machine.

0:54:290:54:33

So far we've drained the ocean from the coast to the deepest point on earth.

0:54:370:54:42

We've followed the journey of the sea bed

0:54:420:54:45

from its birth at the mid-ocean ridge to where it collides with the land.

0:54:450:54:49

We've seen the enormous forces

0:54:490:54:51

that drive the whole cycle of the sea floor,

0:54:510:54:54

yet we've overlooked the water itself.

0:54:540:54:57

Without it, there would be no life on earth.

0:54:590:55:05

So what would happen if the earth really did lose all its oceans?

0:55:190:55:25

Seriously scary things would happen, that's what!

0:55:250:55:30

Without the weight of the oceans, the mid-ocean ridge

0:55:310:55:34

would erupt violently, the planet would unzip

0:55:340:55:37

around the mid-ocean ridge.

0:55:370:55:40

Vast sheets of lava would explode into the sky.

0:55:430:55:48

Without the weight of water to support their sides,

0:55:500:55:54

the continental shelves would collapse.

0:55:540:55:56

Mud slides and dirt avalanches bigger than anything seen before

0:56:000:56:04

would be unleashed.

0:56:040:56:07

Massive pockets of methane gas would explode.

0:56:100:56:13

All this would cause hundreds of devastating earthquakes.

0:56:160:56:20

And with no water, there would be no weather,

0:56:250:56:28

no rain.

0:56:280:56:30

The entire planet would become a desert.

0:56:300:56:33

There would be nothing left alive.

0:56:330:56:37

Luckily, that's not going to happen.

0:56:450:56:47

So let's put it all back again.

0:56:470:56:50

We've seen how the earth works.

0:56:540:56:56

How the machine beneath the sea floor creates

0:56:560:56:59

the biggest geological features on the planet

0:56:590:57:02

and also drives the movement of the sea floor

0:57:020:57:05

to release minerals and gases so vital to life on earth.

0:57:050:57:10

The oceans are one of the most beautiful sights on our planet.

0:57:200:57:25

Hidden beneath the waves are some extraordinary processes

0:57:250:57:28

without which life on earth simply could not exist.

0:57:280:57:33

Subtitles by Red Bee Media Ltd

0:58:090:58:11

E-mail [email protected]

0:58:110:58:13

What lies at the bottom of the oceans? What would happen if the planet lost its oceans? Richard Hammond is going to drain the oceans to find out.

Hidden beneath all that water are some of the biggest natural formations on earth: The longest mountain ranges, the tallest volcanoes and the deepest canyons.

Richard can reveal all this and more in a way never seen before, because he has the ultimate toy - a vast working 3D virtual Earth in a hangar.


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