08x05 - Blue World

[bunniefuu]

- [Narrator] Coming up, Jonathan and Zach

head down to Florida
looking for bull sharks.

But first, Jonathan
ventures into Florida caves

in the name of science,
learning how the aquifer works.

Meet Jonathan Bird,

one of the world's top underwater
nature cinematographers.

Traveling the world on assignment

for all the major networks,

he is an Emmy award-winning authority

on the underwater world.

In freshwater or salt,
reefs, wrecks, or caves,

Jonathan documents the
world beneath the waves.

Welcome to the Blue World.

- For many divers, cave
diving is a passion.

It might seem crazy to want

to explore a submerged underground world

where running out of air
means almost certain death.

But exploring underwater
caves is incredibly exciting

and it has opened our eyes to the way

that aquifers function.

Life on earth depends on water.

While most of the planet's
water exists in the oceans,

evaporation separates
some water from the salt.

When it rains, most of
that precious fresh water

seeps into the ground.

Some is soaked up by the roots of plants,

but some enters the aquifer,
a layer of semi-permeable rock

or gravel that holds
the water like a sponge.

In places where the
topography goes downhill,

the water in the aquifer often flows

slowly downhill with it.

In Florida, the rock beneath
the soil is limestone,

a soft rock made by coral reef animals

millions of years ago
when it was a sea floor.

Rrain falling through the
sky picks up carbon dioxide,

which creates a very mild
acid called carbonic acid.

Over thousands of years,

this mild acid eats
away at soft limestone,

eventually hollowing out caves.

This turned the aquifer in
Florida into underground rivers.

Sometimes the river comes close
to the surface of the ground

and the ceiling gets
thinner until it falls in.

In Mexico, they call it a cenote,

but in Florida, it's called a sinkhole.

This gives divers way into the caves.

Sometimes the underground river
finds a place to spring out.

Florida is full of springs

where this crystal clear water emerges

from the aquifer into daylight.

The Blue World team is heading
to one such place today.

A lot of people don't realize

how important the cave
systems are down here.

They contain the fresh water
that is the drinking water

for everybody in Florida.

They're the planet's plumbing,

and people don't realize
how extensive they are,

how far they go.

They go under the forest,
they go under parking lots,

they go under your house.

They're very extensive systems.

So today we want to demonstrate that.

We have brought with us a
transmitter to take underwater.

Todd and I are gonna
take this transmitter.

We're gonna swim through the cave system,

and the two Zachs are gonna
be up above following us

with the receiver, and they're
gonna see just how far we go.

We've come to Wes Skiles
Peacock Springs State Park

in Florida, home to one of
the most popular cave dives

in the world.

The Peacock Springs system
spans more than six miles

of surveyed underwater passages.

Todd and I are ready for
a long day of exploration

and cave diving always starts
out with lugging the gear.

Man, these are heavy.

Somebody needs to lay off the pizza.

I'm pretty sure he's gonna
get an academy award someday.

Alright, good to go.

Now the fun can begin.

The transmitter is sealed up

inside a homemade PVC housing.

Todd, did you turn on the transmitter?

- Turned it on.

Got it clipped off right here on my side.

- Alright, cool, are we ready, let's go.

We sink down into the cavern zone.

I'm filming and Todd is
responsible for the transmitter

and handling our reels.

- Are you getting a signal?

- Yeah, it looks like I got it.

- Let's see where it goes.
- Let's see where it goes.

Oh, I lost it.

Oh, there it is, there it is.

- As we head away from
the light of the entrance,

we pass the stop sign,

which warns people without
cave training of the danger.


the Zachs are following our
journey with the receiver.

- Think they have this
much underbrush down there.

Probably not, probably
a smooth trip for them.

- Every so often, Todd stops
to hold the transmitter close

to the rock for a good signal.

We have no idea if the Zachs are with us

or not, so we try to
make it easy for them.

- Signal's really strong right here.

- They've gotta be real
close to the surface.

- Then we push on deeper into the cave.

- It's getting weaker.

Oh, gotta keep going.

[light music]

Ooh, the single's getting
really strong now.

They must be pretty close.

- We reach a section of the cave

that angles down much deeper.

We know this will make our signal weaker,

so we can only hope that the
Zachs stay on the same heading

until they pick us up again.

- It's getting weak, it's getting weaker.

It looks like they're going this way.

- Down here, the bottom is
silty, so we have to be cautious.

I can only wonder where the
Zachs are now, what's above us?

- Still got 'em.

- Where are they?

- I don't know.

- Todd tries the ceiling trick
again, hoping it will work

through 60 feet of rock.

[light music]

I am keeping an eye on
the floor of the cave

for one of my favorite cave critters,

and then I find one, a cave crayfish

completely without pigment or eyesight.

As we continue, the Zachs
are crossing a tree farm

and the cave has gone weirdly circular.

Soon, the cave angles shallower

and we have hope that the
transmitter is getting through.

It turns out we're right
underneath the local supermarket.

We can't talk, but fortunately Todd

and I are good at diver sign language.

Which one are they in?

- I'm noticing that in this section,

the water's a little murky.

It turns out we're right
under a cow pasture

and this is no coincidence.

- That way.

- Eventually we turn and head
back to the cave entrance.

What a dive.

- That was great, I
think we got pretty far.

- Yeah, we went really far.

I can't wait to see what those
guys came up with up here.

Our journey has taken us all
over town, beneath roads,

beneath a parking lot, and
most of all, beneath farmland.

While farming is obviously
extremely important

to our food supply,

there can be serious
side effects from farming

or ranching above the aquifer.

A cow, for example, generates

So 100 cows in a field generates
as much as 1,000 people,

and all that waste just sitting in a field

gets washed into the ground when it rains.

Pesticides and fertilizer
on crops do the same thing.

All this contamination
ends up seeping down

into the aquifer.

And guess what else is in the aquifer?

Everyone's drinking water supply.

We're contaminating our own wells,

and when the water comes out
of the spring into sunlight,

the nutrients in the water like nitrates

and phosphates from manure and fertilizer,

fuels the growth of algae and bacteria,

which further contaminates the water

and sometimes even chokes off the oxygen,

which kills the fish.

Legendary cave explorer
and filmmaker, Wes Skiles,

was one of the first
people to sound the alarm.

He used his extensive
knowledge of the aquifer,

gained by years of
diving into these caves,

to help government agencies
understand what was happening

and pass legislation to reduce
pollution in the aquifer

so we all could have safe drinking water.

So yes, cave divers can be
pretty useful sometimes.

Scuba divers are the most passionate

and vocal defenders of the ocean

because we're the ones down
there seeing what's going on.

We can't help but want to
protect the places we love.

Cave divers are a rare breed,

but they're the only
people who actually see

what is in these caves

and have come to appreciate
the importance of the aquifer

and the life that depends on it.

And so cave divers have
become powerful advocates

for the health of these
incredible environments,

the underground heart of the Blue World.

- [Narrator] Don't go away.

Coming up, Jonathan jumps in the ocean

with a bunch of bull sharks.

- I love sharks

and I've been lucky enough to dive

with sharks all over the world.

I've filmed great white sharks in Mexico,

blue sharks in New England,

sand tiger sharks on the
wrecks of North Carolina

and tiger sharks in The Bahamas.

I even learned how to handle
tiger sharks up close.

I've filmed sharks during
the day and at night.

I've filmed them on the
reef and in the open ocean.

I've even filmed them in caves.

It may seem like there's
nothing I haven't done

when it comes to sharks,
but the ocean's a big place

and new adventures always await.

You know I love shark diving,

but I've never done it here in Florida.

Unfortunately, they have a law

that you can't feed sharks here in Florida

within three miles of shore.

So they've developed an interesting way

of doing shark dives way out at sea.

Today, Zach of all Trades and I

have come to beautiful
West Palm Beach, Florida.

The we diving with Pirate's Paradise.

I like the sound of that.

I mean, we're diving
with Pirate's Paradise.

I like the sound of that.

I meet with Captain Rob to
get an idea what to expect.

Arg, the dread Captain Robert the Beard.

Then Zach and I fill out some paperwork

and meet our dive master, Mike Brady.

That's a really lame pirate name.

Alright, here we go.

Then we load our gear onto
the boat for an adventure.

Can't forget the camera.

- Good morning, I'm Rob, I'm
gonna be the captain today.

Some of the basic safety
rules, everybody good?

- We have plenty of time

to assemble our gear while
we travel to the dive site.

Because we have to go three miles offshore

to legally feed sharks in Florida,

that means it will take half an hour

to reach our destination.

I'm starting a cool new look for divers,

sunglasses under water.

Mike says we can expect some bull sharks,

a species not commonly
seen on shark dives.

I sure hope they show up.

This far offshore, the bottom
is more than 100 feet down,

which is too deep for
anything but a short visit.

So the trick is to bring the
sharks up shallower to us.

Mike takes the bait in a milk
crate way down to the bottom

to get the shark's attention.

Once they're interested, he
swims the bait back up to us,

waiting at about 50 feet.

Arg, that'd be 15 meters
for ye metric people.

The first sharks to join
us are the lemon sharks.

Lemon sharks tend to be homebodies.

They find a section of reef to call home

and generally don't stray
too far from that area.

They will come up above the
reef because of the chum.

When you interact with
sharks on the bottom,

they can come up from behind or above,

but they can't sneak in from below.

Here in open water, you have

to keep your eyes constantly
moving to keep track

of sharks in all directions.

Lemon sharks have very pointy
teeth that look aggressive.

The reality is that these teeth
are designed for a purpose.

Lemon sharks feed mostly on fish.

These needle-like teeth
help the shark grab

and hold small slippery
fish to be swallowed whole.

What this means to us as divers

is that these sharks would
never consider us food.

They would not attack
anything as large as a person.

They're simply not designed
to eat food that big.

Their teeth just don't cut well,

so they can't take bites
out of larger prey.

These sharks are just looking for a snack,

something small they can eat in one bite.

Zach of all Trades is
on his first shark dive

and he looks pretty comfortable to me.

- I have to admit, I was a
little nervous to be diving

with sharks for the first
time, but once I got down there

and I was surrounded by sharks,
I realized just how calm

and majestic these animals are
and I was no longer afraid.

- Lemon sharks are
considered a social species.

They often hang out in small
groups, enjoying the company

of other lemon sharks.

So when we chum for lemon
sharks, more often than not,

we get a whole bunch
of them, not just one,

which of course makes for great fun.

The lemon sharks are cool,

but we're really hoping to see bull sharks

and so far, they haven't shown up.

Here off the east coast of Florida,

we're diving in the Gulf Stream,
a strong northward current.

We don't feel the current
at all floating in Midwater

because we're drifting with it.

But as time goes by, we drift northward

with the reef going by down below us.

Soon we've drifted far enough
from the lemon shark's reef

that they begin to leave us

to swim south against
the current back home.

And their departure is
accelerated by the arrival

of another species, bull sharks at last.

Bull sharks look a lot
like plain old reef sharks.

It takes a careful look
to tell them apart.

Bull sharks have a chunkier appearance

and a shorter snout.

For their length,

they're heavier than
similar shark species.

Bull sharks are known for
an aggressive disposition,

especially in the murky shallows
where they normally hunt.

However, here in open water,
the sharks have learned

that divers bring snacks.

They're definitely not on the menu.

It turns out that bull sharks
are actually quite curious.

They spend plenty of time
swimming around between us,

checking us out.

And they seem to like
my lights, so I get lots

of great shots when
they come in for a look.

The action is so exciting that people tend

to breathe rapidly

and go through their air
supply fairly quickly.

So before we know it,

it's time to start making
our way back to the surface.

As long as we still have
some chum, the sharks follow.

After our safety stop,

Captain Rob brings the
boat over to pick us up.

Woo, man, that was some
shark-tacular action, baby, woo!

I've been on literally hundreds

of shark dives all over the world

and not once have I ever
been hurt by a shark.

Sharks are clearly curious

and probably a lot smarter
than most people would expect.

Apex predators like sharks
play an important role

in ocean ecosystems, and their
protection helps preserve

the health of the oceans.

It is my hope

that our adventures filming
these majestic animals

in the wild will help people understand

that sharks are not monsters on the prowl,

but beautiful and crucial
guardians of the blue world.

[bright music]