Original subtitles

[narrator] Previously on Blind Frog Ranch.

On their expedition to an abandoned pit mine...

Eric and Chad hit pay dirt.

-[laughs] That's it. -This is it.

We got gold, boys.

[narrator] While at the Bead Site,

Duane and the team have discovered what they believe is an Aztec altar.

-What are you seeing? What? -It looks like some type of crematorium.

[narrator] And intensified their efforts to locate the entrance

into the keyhole chamber.

-What do you got? -Just dead ants.

I think what we need to do is go up on top and start drilling.

[narrator] Unable to punch into the cave system from below,

Duane makes the bold choice to drill down from above,

sending a sonic drill to blindly penetrate into the mysterious void.

Did you hear that?

-Turn it down. -Watch out.

[narrator] Legends of ancient treasures.

This has to be hundreds of years back.

-[narrator] And unexplained phenomenon... -What the hell is that?

...meet at a 160-acre property in northeast Utah known as Blind Frog Ranch.

Where Duane Ollinger and his team

are digging in search of long-lost Aztec gold.

The Aztecs have discovered this.

-[narrator] But the closer they get... -[Chad] Finally get to

hold some [bleep] gold in my hand.

[narrator] ...the more the land fights back.

-Poison gas. -Go! [bleep] Go!

[narrator] Now Duane will more heaven...

-There we go. Fire in the hole. -...and earth

until he gets to the bottom of this mystery.

We've started this whole deal and we're sure as hell gonna finish it.

[narrator] ...and solves what's lurking below...

Holy [bleep], there's something in there.

Josh!

[narrator] at Blind Frog Ranch.

Drill, boy!

[narrator] After failing to find an entrance below the Bead Site,

Duane is trying to access the keyhole chamber

by drilling along a smoke vent through the rock formation.

Hey, you feel that?

Hey.

It's not me.

Shut her down. Shut it down, Denzel.

[Charlie] Where all that come from?

What happened?

-[Josh] Your pipe dropped. -[Denzel] About ten foot.

It's got to be in that cave system.

What the heck?

Where'd that come from?

You guys got mining going on over there?

-No. -No, no mining whatsoever.

Who's down there, Charlie?

As far as I know, nobody, but I'm checking.

Charlie to Chad. You copy?

[bleep]

Yeah, Charlie. Do you hear that?

No, we're out in the open.

But we felt it, man

[bleep]

All right, we'll head back.

Come on. I just got an alert.

-What do you got, Charlie? -I got motion at the pond.

Let me check my cameras.

Wait. There's water shooting up out of the pond?

What the hell you mean, Charlie?

[Charlie] Yeah, hang on.

-The water came up in the pond after the water blew here? -Yeah.

It was just bubbling up.

That's weird.

Ground water wouldn't act like that.

This is not a coincidence.

These damn things are connected.

-You know they are. -Yeah.

Let's go meet on this and figure out what we're gonna do.

What the [bleep] happened over here?

You know, we're drilling, we're pumping the air,

and then... and then we've got a kickback of water.

Shooting straight up.

It went up probably 40 or 50 foot.

It was like somebody had a fire hose down there

and just shooting it straight back up. Unbelievable.

I mean, it's just strange that we have that much flow.

Why do we have this much pressure all of a sudden?

It could have been an air pocket that's been sitting there for years.

Like we get in the oil field, and when we release that air,

then that lets the water come up.

It'll blow like a well.

[narrator] When drilling for oil,

if the drill head hits an air pocket, a reservoir of trapped gas,

the released gas immediately forces its way back up the drill shaft.

The results can sometimes be deadly.

Air pressure will create havoc.

[Josh] It's possible, but there's another option.

It seemed like the water had head pressure on it.

Like there was pressure coming from, like, up above, pushing all that water.

So all that water just blew straight up out of the hole.

[Chad] There's movement below.

-Is that what you're saying? -That's what I'm thinking.

It's not like we just drilled into, like, a little underground pond

or something that would be in a cave.

-There's a ton of pressure. -Yep.

[narrator] When water flows downhill from higher elevation,

the force of the flow is called "head pressure."

An underground river originating high up in the mountains

would have considerable head pressure.

Penetrating that flow with a drill

could create a significant burst of water.

I mean, we're at the foot of the Uintas.

So I mean, think of the mountain like a giant water tank.

Oh, yeah.

And then he just... he just punctured it at the bottom.

And that's kind of what it acted like,

and it just blew straight up and out of there.

I think we're dealing with a lot of water.

We gave it a place to escape.

I heard all that. I immediately started looking at cameras.

It was like a burst of water, but I've never seen it do

what I saw on the cameras today.

It was a real disturbance at the pond.

No way.

So this was all at the same time that your thing happened.

-Might be less than a minute apart. -[Chad] Really?

I don't think it's a coincidence.

We know that the pond and the energy zone are all connected.

Maybe there's another connection with the Bead Site.

[narrator] Last year when the team was drilling at the energy zone,

the area suddenly flooded and the water also rose at the pond,

suggesting that the two sites were connected underground.

Did we crack open an underground river or something?

[narrator] Now, the sudden flooding at the Bead Site and the pond...

...suggests it's the possibility of yet another underground connection.

-They could all be connected. -I believe so.

[narrator] But it's the timing of the water bursts, only one minute apart,

that reveals something even more critical.

What if this is some type of underground water diversion system

like the manmade aqueduct?

[narrator] When water travels naturally underground,

it flows on a slow and meandering path.

But the quick succession of bursts at the Bead Site and the pond

indicate that the water must be flowing swiftly and directly,

such as in an underground aqueduct.

Water doesn't lie. There's something going on there.

What if chicomoztoc really is underneath our feet?

We're talking maybe hundreds, if not thousands of people

having lived underground at some point, you know.

They would have required a water system.

And we drill into like an aqueduct or something like that.

I mean, it's a possibility that they were diverting water.

[narrator] An aqueduct is a manmade structure that carries water

from one place to another using gravity.

They can be open air canals, elevated arches or even underground channels.

The earliest aqueducts are from the 7th century BC Egypt,

and carried water from the hills

to irrigate crops on the plains.

Later, in the 4th century BC, the Romans constructed

an elaborate system of aqueducts throughout the Empire,

which supplied water to major cities for drinking, bathing and sanitation,

But by the 14th century,

the Aztecs had mastered the control of water.

Their capital, Tenochtitlan, was built in the middle of a lake,

and they used an intricate system of underground aqueducts

to contain and manage the water.

The Aztecs, I mean, they managed water underground.

It's crazy. I mean, there's still remnants of it today.

[narrator] What James is suggesting is that the team

might have drilled into the remains of an aqueduct

built by the Aztecs,

that is still channeling fresh water down from the Uintas today.

Duane, so if it is the Aztec or their ancestors,

maybe you and I need to head to Mexico.

Go and see how they were diverting all that water.

And see how the Aztec themselves were actually doing it.

I think we want to see how this underground system works

and see if we can find some similarities to here at Blind Frog Ranch.

I think that's one hell of a good idea.

James and I will go to Old Mexico and see if we get any hints down there.

I don't know jack [bleep] about aqueducts,

but I hope it's going to give us

the answers that we need to make this project go forward.

Let's go.

Let's get the hell out of here.

It's good to be back in Mexico City, and wait till you see it.

It's going to be interesting if we can put any of this together.

[narrator] James and Duane have traveled nearly

2000 miles south to Mexico City to meet with a local expert.

I want you to meet a historian that I know

that has a wealth of information on the Aztec aqueducts.

I think that will help us understand

what the hell we're dealing with up there at BFR.

-Julio. -There he is.

Hola. What's up, James?

-Julio. -Duane, the man himself.

I hear you're the expert of this whole deal.

The reason we're here is we think there's some underground

water systems at Blind Frog Ranch,

and we think you can tell us what's going on up there.

[Julio] You're in the right place.

The ancient Aztecs, they were masters of managing water and aqueducts.

So why don't we head to Tlatelolco.

There's the remains of the water systems and some aqueducts.

-I'm all for it. Lead the way, man. -Ready?

Welcome now to Tlatelolco.

This is one of the most important archeological sites inside Mexico City.

-[James] Wow. -What you're looking at is just a small percentage

of what it used to be.

This was a great ceremonial area.

[narrator] The ruins of Tlatelolco

show evidence of over 60 Aztec temples, ceremonial altars

and a recently discovered mass burial site

containing the remains of nearly 200 sacrifices,

as well as a complex system of aqueducts leading to a great cistern

in the heart of the ancient city.

The indigenous people, they couldn't drink the water around the cities

because it was salty.

Aqueducts used to bring water more than four miles

from the inside of the mountains into the center of this area.

Wow.

[Julio] They built aqueducts underneath so that the water could flow

inside the temples.

For the indigenous people, water inside the earth,

They would go into this water and they would deposit offerings.

Really?

Offerings were placed there for religious ceremonies.

Just like what we're finding at the Bead Site up in Blind Frog Ranch.

There's an eye socket right there.

[James] This is amazing.

[Duane] So you showed us all the above ground stuff.

What about seeing the underground?

Well, there's a perfect place called Teotihuacan.

[narrator] To better understand the kinds of aqueducts and tunnels

the Mesoamericans were capable of building underground,

Julio takes Duane and James thirty miles outside of the city,

to the ancient pyramids of Teotihuacan.

[Julio] Gentlemen, welcome to Teotihuacan.

[James] Wow. Wow. Wow.

Just amazing.

[Julio] We are up in northeast of Mexico City

and we're walking on the first cosmopolitan city of the Americas.

[James] Really?

[narrator] At its height in the 5th century AD,

Teotihuacan was home to some 200,000 people,

making it one of the most densely populated cities in the world.

To accommodate the needs of so many, they engineered a vast network

of water collection stations, storage reservoirs and sewer systems.

[James] Look at the size of this.

[Duane] Who built this, it's pretty amazing.

Teotihuacan translates as "The city of the gods."

-[Duane] Yeah. -This This was a sacred place, where a lot of ancient people,

ancient rulers, they would come up here

to worship important deities

totally related to water, fire and corn.

-The elements. -[James] That's interesting.

Here, the most important deities the storm, the rain.

Tlaloc is one of his names.

Tlaloc give us the rain.

The frogs sing to Tlaloc. They sink to the rain.

And that's true because here, when we have the rainy season,

other frogs come out and they sing.

That's what we're named for up there.

It kind of makes you wonder if there's any, uh, similarities.

I guess, you know, I know that's kind of farfetched,

but maybe it's not.

The same people. They had the same gods.

It doesn't matter where they were.

[frogs croaking]

It's interesting the way they built with the concrete

that they were using here, the different rock.

[Julio] The concrete covered everything here.

-Kind of reminds you of somewhere, huh? -Yeah.

[James] The altar we found at the Bead Site

was made of very similar materials.

-Almost like concrete. -Concrete?

I'm 99% sure it's concrete.

Look at the water system.

[Julio] That's the way they would drain the water to the river.

[James] I'll be darned.

[narrator] Julio leads them beneath Teotihuacan's largest structure

the Pyramid of the Sun.

[Duane] Wow.

These are sunken patios, and all this was filled with water.

Here we are. We actually see symbols

related to Tlaloc, the rain deity.

But also the deity of the... of the mountains.

The natural flow of the water coming from the mountains.

They would fill in all these spaces.

-Where the water collection took place underground. -[Julio] Yeah.

Exactly.

The real deal is underneath.

[Duane] Lead the way.

The water from the patios outside,

that water was collected from the rain.

And that water would flow into these rooms.

And here it would be like a shower.

They're going to perform rituals on that side.

And here they were washed.

[James] The engineering is amazing.

They were taking ritual baths here,

but the Europeans were maybe taking several baths the entire year.

Someone must have stunk.

[Julio] Hey, watch your step, everyone.

-Careful. -[Duane] Got it. Got it.

[narrator] Duane and James follow Julio

to the lowest depths of Teotihuacan

through a maze of recently discovered hidden tunnels.

It was just amazing how dark it was.

As we went deeper and deeper, I could barely see.

It was so quiet.

You could hear a pin drop from 20 feet away.

It almost felt unnatural.

They must have it felt like it was a holy place.

[Julio] So, gentlemen, now we're going to go to an interesting spot.

Damn, that's a long ways down.

-How deep? -[Julio] Twenty-three meters.

[narrator] The shaft descends over 75 feet deep.

Experts are still unsure of exactly how the shaft was created.

But they know it was dug by hand.

We've had equipment all our lives, big equipment,

and I didn't see how our equipment

could even come close to building what they got.

It was crazy to think they did that by hand.

I'm convinced that we've got an Aztec aqueduct underneath the ranch.

Now we just have to figure out a way to test that theory.

Well, Duane, just think about this.

I mean, if they were capable of doing this here.

What's underneath the ranch?

-[Duane] Oh, yeah, yeah. -[James] I mean, look at how down.

I mean, that's deep, and that's in a super hard rock.

[Duane] Yeah.

You know, it's damn sure as deep as the energy is on, really.

-Yeah. -We saw a 75-foot shaft, it appeared to be the same

as what we saw in the energy zone.

[narrator] Last year when mapping the energy zone with a magnetometer...

[device beeping]

[narrator] ...James discovered a similar hole that was nearly 90 feet deep.

There is a void right here.

Look at that [bleep].

There has been a hole there before. Right here.

[narrator] At the time, they believed it might be a ventilation shaft.

[James] If we have some type of underground cavern system,

what are they going to have to do to be able to breathe?

-So you're saying that could be a vent? -[James] Exactly.

[Julio] They found at the bottom the remains of a female in pregnancy.

-Down at the bottom. -Yeah.

In Mesoamerica,

women that passed away during pregnancy were considered sacred.

-So this is a sacred burial site. -Wow.

It just makes you wonder what exactly is underneath our feet

at Blind Frog Ranch,

Thought we found a vent shaft.

But maybe it's a burial chamber.

What's going on?

-Gentlemen, where's the tequila? -[James] Hey, Josh.

[Josh] What'd you learn in Mexico?

[James] Man, it was really interesting.

The entire city of Tenochtitlan

was based on multiple aqueduct systems.

Both above and below ground.

We were able to see quite a bit of how the Aztec, like,

stored, routed and collected massive amounts of water.

I mean, they knew what the hell they were doing.

So moving water was central to their culture.

They moved a crap ton of water.

-Huh. -And looking at what we saw,

I really think that what we have between

the Bead Site and the pond may be very similar.

So that could explain what happened at the Bead Site.

It's damn sure interesting.

[James] Yeah, I think there's a good potential

that what we have happening at the Bead Site is an Aztec aqueduct system.

That makes a lot of sense.

Look, Josh, we need to come up with a plan.

Maybe that aqueduct will lead us to another entrance.

I want to know how that's connected.

[narrator] If there is an aqueduct beneath the Bead Site

flowing down to the pond,

then it must lead somewhere.

But the question is where?

How can we figure out a way to track the water below ground?

Would a ground-penetrating radar work?

We're down there pretty deep, and I don't think GPR

is gonna be able to give us the detail

that we need to be able to map out where the water is moving.

I think we just drop a beacon down in there.

And it will flow with that water.

It's going to send a signal back.

And then from the surface, we can track that beacon.

I haven't really used one before.

I can check with Chad. He's a pilot.

I'm all in.

[Josh] All right, let's do it.

-Chad, we got all this stuff right here. -Good deal.

So, Josh suggested that we drop a beacon

to track the water flow between the Bead Site and the pond.

With aviation, if they ever have a wrecked airplane over the ocean...

-Mmm-hmm. -...they have these beacons they can track.

So this is called an acoustic beacon right here.

The noise this makes is it's like a sonic ping, like a submarine.

-Cool. -When it touches water, it starts activating.

-So we can track it. -Perfect.

As long as you have a continuous body of water,

you can hear acoustic beacons from hundreds of miles away.

So even though the aqueduct runs deep underground,

we should be able to hear the beacon signal

from the surface body of water,

even if there's only a tiny bit of water connecting it.

But if there's rocks in between blocking the water,

we won't be able to hear the beacon signal.

Our beacon also has a low frequency transmitter

that should be able to reach us

if we're within a few hundred feet.

So we'll be able to track this signal through the water.

But the trick is, we need to be listening to this.

And here's our hydrophone to track it.

Just put it on like a headphone.

-Okay. -These things will pick up the ping that this sends out,

-and you can hear it. -Okay, so this end goes in the water

-and this is what picks up the sound. -Right.

-Yeah. -[Josh] I plug this into a phone.

-Yeah. -All right. Gotcha. Gotcha.

[Chad] And then we also have, like, a tracking app.

That'll take the pings we hear and triangulate

the relative location of the beacon

based on the strength of those pings

-and the change in the frequency. -[Josh] Okay.

[Chad] So if it's moving towards us, the frequency speeds up.

And when it's moving away from us, it slows down.

[Josh] Got it.

So if the water that you found here at the borehole

is truly connected to the pond,

then we should be able to hear it

with the hydrophones in the pond.

And if we're really lucky, this could lead to a new entrance.

-[Charlie] That should give us some answers. -[Chad] Yeah, exactly.

Okay. So we'll get the hydrophones in the water, be set up,

-and then you're gonna let it rip. -[Chad] Yep.

Radio me, and then I'll drop it.

-Perfect. -Good job, Chadro.

[narrator] While Chad waits for the signal to drop the beacon

down into the borehole,

Duane, Charlie and Josh hurry over to the pond.

[Josh] All right, here we go.

[Charlie] Yeah, let's do it.

[Josh] I got two of these hydrophones.

Perfect, Josh, right in there.

[narrator] Josh has placed two hydrophones in the pond

to try to trace the path of the underground water

that flows from the Bead Site to the pond.

[Josh] All right, Duane. The system's up and running.

All right. Back up.

When we drilled that hole up top, this pond reacted.

So we need to know, what is that connection?

-And if that beacon moves... -[beacon beeping]

...and if we can pick up that signal,

then we know there's actually flowing water

underneath us in a cave system,

and that can lead us to a new entrance.

Josh for Chad. The system is up.

It's ready. Go ahead and drop that beacon down the drill hole.

Here we go.

Three, two, one.

All right. It's in the hole.

[Duane] Let's see what we've got here, Josh.

I'm not picking up anything. On the pad there's nothing, either.

I got nothing.

This should show us that the beacon is actually sending out a signal.

It's not done nothing yet.

What's the distance between the pond and the drill hole?

[Duane] Probably a thousand foot.

Where's it at?

I'm not getting anything just quite yet.

With any technology, I mean, especially when

you're putting stuff underground,

you have no idea if this stuff is really gonna work.

So, I don't know. I don't know what to do from here.

I don't know that I can do anything.

This beacon could have turned down another path or been diverted.

Who knows what's going on under there?

This could be all for naught.

Wait, wait a minute. Hang on.

I'm getting something, Duane.

Okay, there we go. There we go.

The beacon's sending a signal right now. You see it.

-[beacon beeping] -[Duane] Damn sure, yes.

-The beacon's about 800 feet from here. Yep. -Yeah.

That's amazing.

Duane, I think that thing's moving.

[beacon beeping]

That beacon is like 300 feet away right now, Charlie.

That thing's traveling pretty fast.

That cave must be a pretty straight shot across there.

It's only a couple hundred feet away from us right now,

-Wow. -So that beacon has traveled from a thousand feet away,

-which is where the drill hole is... -[Charlie] Yeah.

...and it's still moving.

-Guys, that beacon's right here. -Right below us.

[Josh] Yeah, right below us.

[beacon beeping]

[Duane] So what's amazing is this is confirming a theory

that the underground cave system is an aqueduct

leading from the Bead Site to the pond.

We've got to figure out where it's going.

[Josh] It looks like it's moved past us.

-The current's still got it, then. -[Josh] Where's it going?

We should put those hydrophones

in the next closest body of water

and see if we can pick up the signal again.

-What do you think, the creek? -[Duane] Yeah, I think so.

So we need to chase it then.

We got a wild goose on our hands.

Let's go down that creek. Let's go.

[Josh] That was amazing.

This could lead to the entrance.

So I'm gonna name this beacon, Carmen Sandiego,

and follow it wherever it goes in the world.

I'll get us down here to the creek.

-That's the nearest water to the pond then. -Yeah.

[narrator] After tracking the beacon from the Bead Site to the pond,

Josh, Duane and Charlie are now headed to the next closest water source,

Mosby Creek, where they will place the hydrophones in the water

and hopefully trace the beacon signal again.

I need a good spot where the water is kind of slow.

I don't want to be in the quick water.

[Charlie] That's pretty quick down there.

We've got a little eddy right here.

I think that's going to be our best spot.

-[Charlie] Kind of like fishing. -Hang on, guys.

-Hang on. Hang on. -[beacon beeping]

Yeah, guys, I got it. I got it. I got it.

-What's that mean, Josh? -[Josh] Well, it's moving.

It's moving that direction.

It's to the west of us.

How far away are we from the edge of your ranch?

Half a click.

This beacon's gonna leave your ranch, Duane.

How long does that beacon last?

Thirty days.

So here's the deal. If that thing lasts 30 days,

we're gonna have to go from watering hole to watering hole

and find out if we can pick it up.

The sooner the better.

-All right, let's do it. -Yeah.

We're on it now, Duane.

[narrator] The updated triangulation of the beacon signal strength

indicates that it's still moving to the west.

We got a signal. Thank God.

But this beacon looks like it's going off the ranch.

So wherever that beacon goes, we're gonna stay on its tail.

If that beacon winds up in the middle of the Great Salt Lake,

I will be there.

Because as far as I'm concerned,

that beacon takes us to treasure.

-So where'd that beacon go? -The creek over there.

Down... down where we come in the ranch.

And it was moving. That thing was moving.

-Is this your man? -Yeah. Hell yeah.

-He's got a boat with him. -All right.

[narrator] In order to track the beacon

into the deeper Utah water systems,

-Skinner. -...Duane has called on a familiar face.

Welcome back, man.

[narrator] Ryan Skinner, an expert in Uinta Basin geography...

[Ryan] Let's keep going. The ridge is that way.

[narrator] ...who last year helped the team track down the collapsed mine.

Guys, you can feel cold air coming out from down here.

Are you [bleep]?

[narrator] That they know now sits on the South Cave fault line.

Let's go show him around what we've got.

Let's pile in there.

I'm Ryan Skinner. I've written nine books

on the topic of unusual folklore all throughout the basin.

Stories of treasure and other lost history.

[Josh] This is the Bead Site right here.

And we drilled right at the top of the Bead Site.

And we drilled down. We got way down there

and water just shot right back up.

And when that happened, Charlie noticed that down here at the pond,

that thing bubbled, like, almost the same time.

And then we dropped the beacon right down in there.

[Josh] That beacon sends out a pulse.

I can put hydrophones in the water and track that thing,

but we're at a little bit of a standstill right now.

That's why Duane called you in.

That beacon left the ranch.

So now we don't really know exactly where to go

or where the next water source is.

You're the guy 'cause you know this country. I don't at all.

[Ryan] So there's clearly a connection between this point here.

Going down to here.

-And where is it going at that point? -[Josh] Exactly.

[Ryan] I'm really impressed by the technology.

Knowing that they're actually tracking the beacon is pretty exciting to me.

Rather than running around all throughout this place,

we're really going to narrow this down and find out precisely

where this beacon has traveled to.

It has the potential to lead us directly to the entrance.

[Josh] According to the tracking app, we at least know it was headed west.

[Ryan] So if it's headed west, that will take us across Mosby Creek.

Then the next place of water that way are Lake Anaconda

and Pole Creek Sink.

Those are both known to flow underground, so they might connect.

Great.

[Ryan] Josh and I can go check out the sink.

Chad and James, you guys can go check out the lake.

And if those don't work, we can check out Ghost Creek which is just to the west.

Perfect.

-Let's go. -Lead me to the water, man.

Good luck, fellas.

[Josh] All right, Skinner, let's find that beacon.

[narrator] The team heads west, following the beacon's

last known trajectory away from the ranch.

The plan is to deploy the hydrophones in the bodies of water

that Ryan thinks the beacon could be headed towards.

If they can reestablish contact with the beacon,

it could lead them to an entrance

into the Aztec aqueduct system,

that the team could use to backtrack to the keyhole chamber.

I know the creek next door spills into this body of water,

yet it never rises.

Like, it's draining into some other large system.

[Josh] Well, that sounds interesting.

Oh, wow, look at all the sinkholes.

-[Josh] There you go. That's cave formation there. -[Ryan] Yeah.

Yeah, it's a collapsed cave.

Well, if you have this large of a cave system,

you're going to have sinkholes.

[Ryan] That makes sense.

[Chad] This should be it.

Just down the way.

-Look at that right there. He's right. -[James] Oh, yeah.

Let's put the hydrophones in the water and see if we can hear anything.

-Yeah. -[James] We should be able to track it.

if it's in this area.

So Skinner's identified a couple of bodies of water that he wants us to check out

to see if we can hear that beacon signal.

This lake sits in the direct path

that the beacon was headed towards.

If that beacon is here, we'll hear it loud and clear.

[Ryan] All right. The road ends right here.

[Josh] Oh, yeah, it's not even a road anymore.

[Ryan] We're gonna have to get out and get on foot at this point.

Let's track this thing down.

Did you hear that?

That's a good sign.

Holy [bleep]!

We're actually in a cave right now.

That's a lot of moving water.

But if that beacon was coming down this water,

you'd get hung up on one of these rocks.

[Josh] Yeah. Where is this water going?

-It's got to be underground, some sort of channel. -Right underneath here.

[narrator] Subterranean rivers occur in karst topography

composed primarily of limestone,

typically made up of the fossilized remains of ancient sea creatures

cemented together over millions of years.

As acidic water passes through cracks in the limestone layer,

it can carve out tunnels underground

and ultimately form an underground river.

The area where water on the surface enters

into an underground river is known as a sink.

While most caves formed by subterranean rivers are stable,

the continued erosion of limestone by water passing through

can carve away enough supporting rock

that the entire cave collapses, forming a sinkhole.

For a giant cave complex you have to have limestone.

This is a mountain of it.

And we've got limestone back here, too.

We're actually in a cave right now.

The ceiling has collapsed.

So this used to be all the way across here.

This creek eroded all of this out

and then the ceiling collapsed. Golly knows how long ago.

Let's take a look.

That sink should be right around the corner down here.

[narrator] Ryan is guiding Josh to Pole Creek Sink,

a body of water a few miles west of Blind Frog Ranch,

in an attempt to reestablish contact with the acoustic beacon

the team dropped into an underground water system at the Bead Site.

Yeah, that's a lot of water. This is amazing.

Look at this.

Yeah, it's beautiful, but I wouldn't want to go swimming in it.

[narrator] The beacon signal has led Josh and Ryan

to a dangerous natural formation called a sink.

Here, the surface water flows directly underground through a swallow hole.

Get too close and it could drag you under.

This water's going underground right here.

Where the beacon's flowing through.

This water is probably touching it.

This is the perfect place to put in those hydrophones to see if it's here.

I'm gonna put it in right here.

Yeah, it looks like it goes pretty deep.

Nice.

-You hear anything? -I don't hear a thing.

[Chad] Yeah, [bleep].

We're gonna have to find another location that's connected.

Yeah, this body of water is a bust.

We're gonna head to the next body of water that's on, uh, Skinner's list.

-I hear it. -[beacon beeping]

I hear it.

It's a good signal.

Let me check it on the pad, too.

[beacon beeping]

Look here, it's moving.

Do you see that?

We're back in the hunt.

It looks like it's headed right through the mountain.

It's got to be a massive channel going that way.

All right, let's pull these hydrophones.

[beacon beeping]

This way.

Oh, look there.

That's what we wanted to see right there, Skinner.

That ain't from the rain.

Let's put the hydrophone in the water

and see if we can pick up the signal on that beacon.

And then we'll know that this water is connected

to where we dropped the beacon.

-Right away, yeah. -[Josh] You got something?

Holy [bleep], that's loud.

-It is screaming. -[beacon beeping]

I'll tell you what.

That signal is steady.

I'm not hearing a change.

I don't think that beacon is moving.

It's right here.

Let me just triangulate so that we can get closer to it.

Oh, yeah.

[beacon beeping]

Oh, wow.

So the cave itself could be punching right into this body of water.

But how do we pinpoint it?

Let's go back and grab your boat and dump the ROV in

and see if we can find it.

We can't see the beacon, but that beacon is underneath this shoreline somewhere.

We've got to put eyes under the water,

and we've got to see where that beacon actually is.

And hopefully, find an entrance into the underground cave system.

-You ready? -Yeah.

[narrator] Josh and Ryan are launching an underwater ROV,

or a remotely operated vehicle to explore the depths of the lake.

Using his tablet, Josh will be able to maneuver it along the bottom

in search of the beacon.

-[device beeps] -Good, good, good. We're online.

All right. Let's launch this thing.

It's still going down. It's still going down.

Wow, it's deeper than I thought.

-What kind of clarity you got? -The visibility is not good.

[Ryan] Let's just try to scan the shoreline.

[Josh] There we go. There comes some rock right now.

Okay.

There's a lot of rubble right over here.

-[Ryan] Oh, yeah. -And you'd expect to find that if there was, like, a cave in.

So let's keep moving up this direction.

Right over here along the shoreline, Skinner.

-You see that big rock? right across here. -I see it.

I mean, it almost looks like a collapsed wall of stone.

Oh, look, there.

Right there. Right there.

-Look... look at that. -Yeah.

Does that not look like an entrance to you?

Like, No, [bleep], that's it.

That could lead right to a cave.

This could be an opening into a cave system down there.

There's no telling what could be in that cave.

We've been looking for an entrance, and that could be it.

That's awesome.

[narrator] Next time on the season finale of Blind Frog Ranch.

So we think that beacon is in here somewhere.

[narrator] After locating a potential entrance to the keyhole chamber

with the beacon,

Chad must dive into the flooded cave system.

You know, this underwater cave diving, it's dangerous as hell.

[man] Think you could dive that?

Yeah.

We're possibly looking into one of the entrances to chicomoztov.

[grunts]