BBC Learning English. I'm Neil.

And I'm Rob.

From the ancient Roman sea god,

Neptune, to myths of mermaids,

to modern Hollywood films

like Finding Nemo, people throughout

history have been fascinated

by the idea of living

underwater. In this programme, we'll be

hearing about projects to

create liveable underwater

habitats and the challenges they face.

We'll be finding out how realistic it is

to believe that in a few years we could be

eating breakfast whilst watching fish

swim outside the kitchen window,

before heading

off to work in an office under the ocean...

... and we'll be learning some related

vocabulary as well. But first it's

time for our quiz

question. One of the first adventure

stories to fire the public's

imagination about the

underwater world was the 1870 novel,

Twenty Thousand Leagues Under

the Sea. But who wrote

this underwater classic? Was it:

a) H G Wells?, b) Arthur Conan Doyle?, or

c) Jules Verne?

I think I know this one, Neil.

Wasn't it a) H G Wells?

OK, Rob, we'll find out later if you're

right. Now, one of the

most ambitious designs

for an underwater city is Ocean Spiral,

a huge transparent globe attached

to the seabed -

the solid ground which lies

deep below the sea level.

The top of the globe stands above the

surface of the ocean and

running through the centre

is a tower to add strength, and to provide

space for homes, offices

and even an amusement

park for five thousand

underwater residents.

Ocean Spiral has been dreamt up

by the Japanese Shimizu Corporation.

Here's Shimizu engineer,

Maksaki Takeuchi, explaining to BBC

World Service programme,

CrowdScience, the motivation

behind the idea:

At the moment the world is facing a lot of

serious problems regarding

food, energy, water,

natural resources... however we are trying

to solve the issues just by using our land.

Our idea is to connect the sea surface

and the deep sea vertically

and that way we believe

that we can utilise the capability of the

deep sea and that's the purpose

of this whole project.

The effects of human activity on the land

have led some to look to the

oceans for natural

resources - naturally existing things

such as minerals, oil, coal

and other energy sources

that can be used by people.

This search deep underwater is

happening vertically - at a ninety

degree angle straight up or

down from the ground, as opposed to

horizontally, or flat across the

Earth's surface.

But as yet, Shimizu Corporation's plans

for an underwater city

are still in the planning

stages - no part of the project has yet

been built and the total cost

is thought to exceed

26 billion dollars.

In fact, the longest anyone has spent

living under the sea is only 73 days.

That record

was set by Roger Garcia, ex-military diver

and head of The Aquarius,

currently the world's

only underwater research station.

Here's Roger Garcia, explaining to BBC

World Service programme,

CrowdScience, what happens

to the human body after living

underwater for so long:

... perhaps a change in their voice, not

much 'cos we're not very deep,

that's because

the air becomes denser. Physiologically

the most important thing though,

is that since

you are in this case at two and a half

times atmospheric pressure

you do take on more inner

gas, and in this case - inside The Aquarius

we just breathe normal air - you're gonna

take on more nitrogen and depending on

how long you stay in The Aquarius,

that's going

to incur some sort of

decompressed obligation.

In addition to engineering challenges,

living underwater for long periods

of time also affects

the human body. One example is the

bends - or decompression sickness,

a serious medical

disorder created by nitrogen bubbles in

the muscles when returning

to the surface of the

sea too quickly.

The bends, and changes to the voice,

are examples of how underwater

living changes the body

physiologically - relating to how the

bodies of living humans

and animals function.

As divers descend deep below the

ocean's surface, there is

an increase in atmospheric

pressure - the normal air pressure

within the Earth's atmosphere.

The deeper they dive,

the higher the pressure. Physiological

reactions like the bends are

caused by divers incorrectly

readjusting to normal

atmospheric pressure.

Well, Neil, with so many difficulties,

it's no surprise that HG Wells's

fantasy of living

under the sea is still science-fiction.

Ah, but are you sure it was H G Wells,

Rob? In my quiz question

I asked you who wrote

the classic underwater adventure

Twenty Thousand Leagues

Under the Sea.

Yes, and I said a) H G Wells.

Which was... the wrong answer!

It was, in fact, c) Jules Verne,

the French author who also

wrote Around the World in Eighty Days.

In this programme, we've been discussing

the challenge of living underwater, going

down vertically - at a 90 degree angle -

to the seabed - the solid ground hundreds

of metres under the sea.

Ocean explorers search underwater

for natural resources - useful

materials like coal and oil.

But they face many physiological

problems - problems relating

to how the human body

functions, such as the bends - a painful

medical condition caused by returning too

quickly to atmospheric pressure -

the Earth's usual air pressure.

That's all for this programme,

but we hope

you'll be diving back into 6 Minute English

very soon. Bye for now!

Bye!