07x12 - Cave Bells in Mexico

[bunniefuu]

[bright music]

- [Narrator] Today on Blue World,

the spectacular spawning
behavior of bumphead parrot fish,

but first, rare mysterious
formations in a Yucatan cenote.

Meet Jonathan Berg.

[water splashes]

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.

[bright music continues]

- [Jonathan] The jungles
of the Yucatan in Mexico

are filled with incredible wonders.

The limestone beneath the jungle

is filled with caves.

All the water in the
Yucatan is underground.

There are no surface rivers.

It flows through these cave systems.

In places, the ceiling of
the cave has collapsed,

producing formations called cenotes.

These cenotes were sacred sources of water

for the ancient Maya,

but for us they are also entrances

to the cave systems below the jungle.

There are all kinds of
interesting things to see

in these cenotes in caves,

from speleothems like
stalagmites and stalactites,

to blind cave fish.

Sometimes there are bones
from animals and even humans,

but a few cenotes hold
something incredibly rare

and not well understood.

In cenote Zapote, yes
that's the actual name,

near Puerto Morelos,

there are mysterious
formations known as cave bells.

To see these mysterious formations,

cameraman Todd and I are
heading down to the Yucatan

for a cave diving adventure.

We meet up with my good
friend Christine Lowe,

an experienced local cave
diving instructor and guide.

She knows just about every
cave and Cenote in the area.

We drive to Puerto
Morelos to visit Zapote.

Todd, Christine and I head
way out into the jungle

to reach Zapote.

Zapote is located in a nature park.

There's a platform above
the cenote to jump in,

but you have to look carefully first

because there are often divers down there.

The rare formations make
this a popular dive site.

- Or you go the second level,

then it's like 11 meters.

- [Jonathan] We have a
walk down to the water

to check it out.

From the surface it sure
doesn't look like much,

but the water seems very
inviting on a hot day.

There are some divers already in there.

- [Christine] We let them
go in the water first.

- [Todd] Yeah.

- [Christine] And then we go down.

- [Jonathan] Stairs make
diving very civilized.

Ooh, that's my favorite part of this.

- That is so awesome.

- I love that part.

Carrying heavy stuff.

Can't forget the cameras.

Finally, it's time to suit up.

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You have to be very careful
not to drop anything

while you do this because
the cenote is so deep

you will never get it back.

Zapote is shaped like a bottle.

It's small at the surface,

but gets wider as we go deeper.

[calm music]

The first thing we see is an ancient tree

that fell in here thousands of years ago.

In this low oxygen environment,

the tree has not decomposed.

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Soon we find the cave bell formations

which look like sponges growing
downward from an overhang.

These are like nothing I've ever seen,

and while they look like sponges,

they definitely don't feel like them.

They're as hard as stone
made of tiny crystals

all growing on top of each other.

In most caves, speleothem
formations like stalactites

and stalagmites were formed long ago

during ice ages when
sea levels were lower,

so the water table was lower.

At the time, the caves were not submerged,

they were dry.

The speleothems were formed
by water dripping from above,

leaving trace elements of calcite

that formed icicle looking
structures of stone.

But the bell formations
have been thorium dated

and they've formed within
the last 5,000 years,

meaning the water level
has not been low enough

during this time for them
to have formed in air.

They're actually forming under water.

Scientists are not sure
exactly how they form,

but they're only found in
seven cenotes in the world,

all of them within a few miles of Zapote.

The current theory is that
there's something special

about the water chemistry
in these seven cenotes,

and there might be a special bacteria

involved in the process,

but somehow calcite crystallizes
into these formations

which start as small nubs
and then grow downward,

getting wider as they grow like bells.

[calm music continues]

Since they're thought to be formed by

a unique relationship with bacteria,

they're often referred to as biothems

rather than speleothems.

Analysis of the growth patterns

has shown that the formations grow

only one millimeter every 10 years,

but even growing that slowly

after about 4,000 years

they get so big and heavy,

weighing hundreds of pounds,

that they break under their own weight.

They fall to the bottom of the
cenote nearly 200 feet deep.

[calm music]

As we wander around the entire
circumference of the cenote,

we can observe thousands
of these formations,

but they only grow in a narrow depth range

of about a hundred feet deep.

It's possible that the water
chemistry is only right

to form the bells for a
narrow range of depths.

As we get a little deeper,
the water gets cloudier.

We're entering a toxic
hydrogen sulfide layer

produced by decomposition
of organic material

that falls in from the forest above.

The bells seem to form right at the edge

of the hydrogen sulfide layer.

Christine leads us into
the center of the cenote

to have a look at the tree.

Carbon dating tells us that this tree

is about 3,500 years old,

but it's well preserved down here

and on one part of the tree

there are little bells forming.

They start out as just tiny little nubs.

The fact that they're forming
on a tree of known age

was the first clue that
helped researchers understand

that the bells form underwater.

We spent a long time
down at a hundred feet,

so now it's time to head up
and do a decompression stop

in the shallows before we
can head to the surface.

We spend some time looking at the plants

thriving in the sunshine,

and of course,

hoping nobody jumps on
us from the platform.

[water splashes]

Whoa.

And we can't leave without cameraman Todd

taking the plunge from the platform.

- Woo!

[water splashes]

Zapote is an amazing place.

Every time I think I've seen it all,

I get to see something new that
I had no idea even existed.

The cave bell formations are super rare

and so mysterious that scientists still

don't even know exactly how they form.

It's just another fascinating
mystery of the blue world.

[bright music]

- [Narrator] Coming up, Jonathan films

the bumphead parrotfish
mass spawning event.

- [Jonathan] The Republic of Palau

is an island nation
consisting of more than 500

beautiful unspoiled
islands in the Pacific.

This blue water paradise
is a top destination

for scuba divers from around the world.

There's something for
everyone here in Palau,

including massive coral caverns,

beautiful reefs,

ship and plane wrecks from World w*r II,

high energy reef hook
dives in strong current,

sharks,

and even swarms of harmless jellyfish.

And among all the fish
frequently seen here,

the bumphead parrotfish
growing to more than

a meter in length is one of the biggest.

This magnificent fish survives

by chewing the algae from the reef

with its massive front teeth.

Because of its size,
the bumphead parrot fish

has been overfished
throughout the Pacific,

but in Palau protection since 2006

has created one of the
largest and most healthy

bumphead populations in the world.

Located 500 miles east of the Philippines

in the middle of the Pacific Ocean,

Palau is well off the beaten path,

a remote oasis in the sea.

Julia and I have come
here to dive for a week

with the Rock Island's Aggressor,

a luxury dive yacht based in Palau.

We will live, eat, sleep, and
dive from this beautiful boat.

Today we're heading out to do a dive

at a famous site called Chandelier Cave.

[bright music]

A short boat ride later

we reach a spot with a
spooky hole in the sea floor.

As we head into the cave,

I immediately start to wonder
about doing a cave dive

without proper cave diving gear.

But this cave has something
making it different

from most of my cave dives.

The chambers are only three
quarters full of water,

so we are in a true cave
with no ambient sunlight,

but we can surface to breathe.

That's why they can bring
open water divers in here

without cave training or
serious cave diving gear.

In an emergency, you can
always surface to breathe.

Inside there are beautiful
flow stone formations

still forming from dripping
water above the surface.

[calm music]

As we explore further, I
can see a change in color

on the formations indicating
the boundary layer

called the halocline.

The white rock above the line

indicates the freshwater layer.

The darker rock below the line

has marine growth from the seawater layer.

Of course, during the last ice age

when so much water was
locked up in glaciers,

the oceans were a hundred meters lower.

This cave would've been bone dry.

I'm swimming across the
ceiling of a huge room.


I would have to walk on
the floor 50 feet below.

I follow our guide into the next room.

There's a place where we can climb up

out of the water a little.

This allows me some leverage
to lift my heavy camera

out of the water for a shot of the room.

As we continue back out of the cave,

the walls below the
halocline show patterns

created by thousands of years

of being eroded and
dissolved by sea water.

The softer parts have dissolved away,

but the harder parts,

probably marine creatures encapsulated

within the ancient reef limestone,

are still there, defiantly sticking out.

Soon we can see the light of the entrance

and make our way back to the sun.

After the dive, we head
back to the Aggressor.

Later, we enjoy an amazing Palau sunset.

[calm music continues]

[background chatter]

Early, and I mean early the next morning,

we get up for a special dive briefing.

Each month on the new moon,

the bump head parrotfish spawn.

It happens really early in the morning.

We need to be in the water by 7:00 AM.

You can tell I'm not really awake yet,

but I need to get my game face on

because this is an important sh**t

for our upcoming IMAX
film, Secrets of the Sea.

We suit up with anticipation
that the fish will spawn

and we'll be able to get good
shots of it for our IMAX film.

When we reach the spot
where the fish spawn,

I can already count six other boats.

Our captain jockeys for a good position.

- One, two, three.

[water splashes]

I hit the water and quickly look around.

I'm not even sure what I'm
supposed to be looking for.

I've never seen this
spawning event before.

Then I notice deep below,

fish gathering.

But all around me divers everywhere.

I slowly sink down into
the midst of the fish.

It's deeper than I expected.

They don't seem to be doing anything,

but you know they're up to something

because you don't normally see this many

bumphead parrot fish together.

There's hundreds, maybe thousands of them,

but then something changes.

The fish all start swimming
in the same direction.

As the females get ready
to release their eggs,

they swim in order to release
them over a larger area,

so they can't be eaten
by predators as easily.

The males follow,

waiting for their chance to spawn.

Meanwhile, I'm swimming as
hard as I can to keep up.

With this much exertion at 90 feet,

I'm going through my air quickly.

I won't have long to get the shots.

Then it starts.

The females rise up in the water column

to release their eggs with
a dozen males following.

[bright music]

When the female releases the eggs,

the males rush in to be the
first to fertilize them.

The entire school of bump heads

breaks up into smaller
groups that are spawning.

[bright music continues]

They leave behind thick clouds of eggs,

the next generation of bumpheads.

I must keep swimming to stay with the fish

and ahead of the other divers,

but I slow down as much as I
can to keep my shots steady,

and I'm getting lucky.

I'm right in the middle of the action.

[bright music]

Julia, who's filming me,

is staying back just a little

so she won't get in my shots.

[bright music continues]

Soon it seems like the
action is winding down.

I mean, how long can they keep at it?

I'm kind of hoping it's over
because I'm getting low on air,

but then another spawning run

right in front of my camera.

Perfect.

However, now we really have to go.

Julia and I are both low on air,

so we rise up to 20
feet for a safety stop,

and Julia does a victory dance.

[bright music]

I can't believe our luck,

I have the shots in the can.

Even though we are done,

the fish aren't.

Deep down below us,

the spawning is still happening.

It's k*lling me that I
can't go back down there,

but I just don't have enough air for that,

or energy.

Palau is one of the most amazing
dive destinations on earth.

Chandelier Cave gives open
water certified divers

a chance to get a feel for
what cave diving is like.

And Palau's spectacular marine life means

there's always something to see.

Bumphead parrotfish,

highly endangered in other places,

thrive here because of Palau's commitment

to the protection of
the marine environment.

It gives us the chance
to see true spectacles

of the blue world.

[bright music]