Journey Into Amazing Caves Page #2

lie buried beneath 500 ft. of ice.

The team cannot descend the deep

until there is a four day cold snap ...

to stop the flow of water.

They soon get their wish.

The other day it was -12 centigrade

with a windshield of -26 centigrade ...

which is colder than a freezer ...

so it was very cold, bitterly cold.

Big-time.

Too cold to be pleasant.

Waiting for the water to

freeze up is the hardest part,

because we're out in

the middle of an ice cap,

there's not a whole lot to do.

This is definitely a caver's haircut.

To prepare for the deep descent,

Nancy has to learn to measure

the movement of the ice,

as the cave walls are slowly pushed in by

the tremendous weight of the glacier.

Oh, so from this point to this point ...

is what we measure

how it closes, okay.

Four days into the cold snap,

Janot decided to risk perhaps

his deepest descent ever,

to get samples for Hazel.

Only days ago this

was a deadly waterfall.

The deeper you go,

the more unstable the ice becomes.

Janot has seen ice boulders burst

from the walls like cannon shots.

loose without warning.

So he purges the

walls of loose ice,

to protect the team

members who will follow.

Sometimes to set ice

screws in the safest spot,

Janot turns himself

into a human pendulum.

Assisting Janot on the descent,

Luc is concerned

about dripping water ...

icing up the rope at 200 ft.

I have rappeled under hundreds

of vertical pits around the world,

but never anything like this.

Ice adds an element

of unpredictable risk.

At just over 500 ft.,

Janot grows increasingly concerned

about the instability of the ice.

This is the second deepest ice

cave Janot has ever explored.

As Hazel rappels,

Janot radios up and warns

her not to descend too far.

Instead, he will bring

her the deepest sample.

A large block of ice above

Janot seems ready to break loose.

He wastes no time in collecting

the samples for Hazel ...

before starting the

long climb back out.

Perhaps the microbes Janot

risked his life for ...

will one day offer

a cure for disease.

But it will take years of

research to unlock that secret.

Some extremophiles can

stay out here for 100 years,

but I have found a few

weeks was quite my limit.

I knew I would miss my

new French friends though.

When you go caving with someone,

you trust your life to them ...

and they to you,

you become friends for life.

The hills near my

home in Georgia ...

are ideal terrain for

the formation of caves.

Just as extremophiles thrive

in the ice cap of Greenland,

bats are well adapted to

classic limestone caves.

These flying mammals sleep all

day and come out at sunset to feed.

are endangered,

but not this colony.

The 20 million bats here eat a half

a million pounds of insects every night.

Thanks to special training,

Nancy can introduce

her class to this ...

under appreciated creature

on a field trip.

Any questions?

What to do bats eat?

Well, this kind of

bat eats, scorpions.

Do you believe that?

I wouldn't want to eat

a scorpion, would you?

And bats eat a lot of insects too,

they get rid of those nasty

mosquitoes that bite your legs,

make you itch.

Like bats, serious cavers will

go a long way to find a good cave.

So when Hazel invited me on another

far flung search for extremophiles,

I was raring to go.

Southern Mexico,

the Yucatan peninsula

juts defiantly into the Gulf.

These ancient Mayan temples ...

were built on one huge

limestone plateau.

The plateau holds hundreds

of miles of cave passage,

the longest underwater

cave system in the world.

The caves are entered

through cenotes,

natural wells.

How did it go, did you

all find anything?

Hey kids, I'm still down

here in Mexico with Hazel,

and we are looking for something

called a halocline.

A halocline is where the freshwater

from the stream, like this,

meets the salt water of the ocean,

and it forms this really blurry layer.

You see this blurry layer?

Hazel thinks there are some special

bugs which live in this halocline,

so that's why we are looking for it.

Well, that's about

it for right now.

And I love you all and give

yourselves a big hug from me.

Goodbye.

To find an uncontaminated halocline,

our guide, Jorge Gonzalez,

led us to a remote cave,

deep in the jungle.

If the freshwater in this cave

flows all the way to the sea,

it must pass through a halocline.

To find out, Nancy and Hazel

used fluorescein dye,

which does not harm

the environment.

If this green dye comes

out where we expect,

at a coastal lagoon,

then we will know that this cave

is connected directly to the sea.

Hazel retrieved the water collector

she placed at the mouth of the

underground stream the day before.

The slightest trace of fluorescein

will show up under my black light.

Since the green dye went

through to the ocean,

we went back to the

cave the next day.

I respect Hazel's decision

to take up cave diving,

but I promised my

family I'd never do it.

Cave diving has been called the most

dangerous adventure in the world.

Survival takes training,

caution and luck.

We are laying a dive line,

it is a bit like leaving

trail of breadcrumbs ...

to find your way back home.

Jorge affixes arrows to the line,

to guide the divers

back to the exit.

There are rules

that we never break.

We always turn around

and head for the exit ...

when we have used up

third of our air,

so we have extra air in case we

run into problems on the way out.

Life in total darkness has made

this species of fish blind.

To compensate, its other senses

have become more acute.

When debris rains down

from the ceiling,

you know that no one has

ever been this way before.

If the silt gets kicked up in a huge cloud

and you lose sight of the dive line,

you may never find it again.

And you could run out of air before you

ever find your way out of the cave.

When we reached a breakdown pall,

I wasn't sure if I could get

through the small passage,

but the volume of

water flowing through ...

suggested that was more

cave on the other side,

so I had to find out.

Open ocean divers wear scuba

tanks on their backs,

but cave divers go sidemount,

so we can squeeze through

narrow passages.

In any really tight spot,

you can remove your tanks,

push them ahead ...

and then follow them

through the hole.

We were approaching

our turnaround.

I will not break that

rule, no matter what.

Just when the cave seemed to be reaching

the right depth for a halocline,

we hit a dead end.

In the few moments it took for

us to hunt for an opening,

we kicked up a huge cloud of silt.

As soon as Hazel and Jorge worked

their way out of the silt cloud,

they headed for the exit.

Just because fluorescein dye

makes it through a passage,

that doesn't mean that we can.

You don't look too happy,

what happened?

I wasn't in much of a talking

mood but my mind was made up,

we'd try a different cave.

The rainforest is an important

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