Original subtitles

NARRATOR: The Andes Mountains, Peru:

towering, inhospitable peaks that push the limits of the human body.

But one lost civilization was notorious for their connection to this rarefied air:

the Inca,

the largest, most expansive empire in the history of the Americas.

In just 100 years, the empire spread across South America,

building elaborate cities and temples, incorporating over 10 million people.

But it disappeared in a matter of years,

leaving mysteries that have puzzled archaeologists for decades.

Now, a scientist is searching for one of their last missing temples,

at a cold and isolated lake, high in the Peruvian Andes.

These sacred waters will push him to the cutting edge of exploration.

♪ ♪

-(vehicle rumbling) -(tires screech)

(men cheer)

In Southeast Peru, a team of scientists are en route

to a remote corner of the country to conduct

the first-ever archaeological survey of Lake Sibinacocha.

Leading the expedition is National Geographic Explorer Preston Sowell,

who's been studying this exotic watershed for nearly 20 years.

PRESTON SOWELL: We're at our base camp elevation... 16,000 feet.

♪ ♪

NARRATOR: Lake Sibinacocha lies at the headwaters of the Amazon River,

surrounded by enormous, glaciated peaks and abundant wildlife.

SOWELL: You never know what you're going to run into

when you take people into the mountains here.

NARRATOR: It's a difficult place to reach,

which has kept out all but the most intrepid scientists.

They've departed from Cusco, the capital city of the Inca empire,

which is still a thriving hub to this day.

From the 1430s, for nearly 100 years, the Inca spread out from Cusco.

They conquered the many existing ethnic groups that spanned

from modern-day Colombia to central Chile,

incorporating their beliefs and temples into a cohesive empire.

But their most important sites are found in the Cusco region.

Places like the ceremonial center of Ollantaytambo,

the spectacular ruins of Sacsayhuaman,

and Machu Picchu, the royal estate of an Inca emperor,

perched atop a sacred mountain, with some of the most precise

and astounding architecture found anywhere in the world.

However, despite its relatively close proximity to Cusco,

Lake Sibinacocha and its surrounding watershed,

have remained largely overlooked by archaeologists,

with little known about its ties to the Inca,

leaving us to wonder what secrets they might have hidden here.

(speaking indistinctly)

Preston Sowell has brought together a group of Peruvian archaeologists

to investigate the lake and its watershed.

They're joined by professional mountain climbers and scuba divers

to navigate the difficult terrain above and below the water.

SOWELL (speaking Spanish): Vamos a Sibinacocha!

NARRATOR: This expedition marks the first time

that trained archaeologists have visited here,

where they will look for structures and artifacts from the past,

exploring the watershed's ridges, peaks, and shoreline

to try and learn what the area might have meant to the Inca.

SOWELL: To convince archaeologists that we might have something special here,

it's really the first step in protecting this place.

-MAN: Beautiful. Man, it's pretty. -TEAM: Woo!

NARRATOR: Arriving at the lake, Preston and the team could finally unlock

the mysteries of this forgotten landscape.

♪ ♪

(birds singing)

At home in Boulder, Colorado,

Preston works as an environmental consultant,

helping corporations and the US government

prevent and clean up environmental contamination.

And for nearly 20 years, he's had his eye on the Sibinacocha watershed,

where he's developed a deep appreciation for the landscape, its wildlife,

and potential significance to the Incas.

SOWELL: I'm not an archaeologist.

My goal is really to use this as a tool to help protect this watershed.

NARRATOR: It all started on an expedition in the early 2000s,

when Preston was studying an emerging frog disease

that was decimating local populations,

and he spotted a surprising species in the water.

SOWELL: I lifted up a rock and a much larger frog took off.

NARRATOR: To Preston, it resembled the critically endangered

Telmatobius Culeus, or Titicaca water frog,

that was known to reside only in the Lake Titicaca watershed,

more than 200 kilometers away.

Titicaca was one of the most sacred places in the world for the Inca,

and if the frog was brought to Sibinacocha for ceremonial purposes,

it could indicate a sacred connection between the two lakes.

SOWELL: It sort of became the thorn in my side.

I spent three expeditions in the lake just trying to find this damn frog.

NARRATOR: During his search for the elusive frog,

Preston made an even more unexpected discovery.

He noticed two strange artifacts in the water,

surrounded by algae and weeds:

a ceramic pot

and what appeared to be a long, zigzagging wall,

built with golden yellow stones, that looked like a giant snake.

He didn't know it yet, but these artifacts would go on to define

the next 20 years of his life.

He had been pulled into a fantastic new world, rich with myths and legends,

and began researching the many mysteries of the Inca,

who left few historical records

after they were overthrown by Spanish conquistadors.

He looked into the Inca's religious beliefs:

that the landscape was alive with gods and spirits,

and that unique alignments of geographical features,

such as the position of different mountains, rivers, and lakes

were considered sacred.

And the thing that interested the Inca most was the high altitude peaks,

where their most important gods resided.

Next, Preston learned that zigzag walls, like the one found at Sibinacocha,

are actually quite rare in the Andean cultural realm,

and almost always discovered near an important place,

like a shrine or temple, often near bodies of water.

In fact, some lakes were considered especially important,

and were called paqarinas,

which means "sacred place of origin" in the Inca's language.

SOWELL: They were not only where people were born from,

but where their souls went when they died.

NARRATOR: The Inca believed that the whole world floated on a body of water,

and each lake was an entry point into a spirit world beneath the surface.

Could Lake Sibinacocha possibly be one of these paqarinas?

SOWELL: At that moment, I thought, we were really on to something.

NARRATOR: As he continued his research, Preston found one name in every turn:

world famous archaeologist, anthropologist,

and National Geographic Explorer Johan Reinhard.

Johan has spent much of his career locating the Inca's

most significant ceremonial sites, at some of the world's highest locations.

JOHAN REINHARD: Probably the biggest driving force in my own life

would be the attraction to mysteries, solving mysteries.

NARRATOR: Johan developed an elite skill set

to help him explore the planet's most hard-to-reach locations,

becoming an expert in climbing, skydiving, and scuba diving.

He used these skills in the highest mountain ranges around the world,

including Peru.

SOWELL: That dude has been everywhere; his shadow just covers the Andes.

REINHARD: One of the reasons the Incas seem so mysterious to us is

because we simply don't have any written language before the Spanish arrived.

That creates a mystery.

NARRATOR: Spanish chroniclers tried to document the Inca's customs,

but their understanding was incomplete,

leaving Johan to figure out for himself

why the Incas were drawn to the highest places.

REINHARD: These were altitudes where they thought the gods resided.

NARRATOR: But these high areas were not always kind,

visiting biblical devastation upon the Inca,

like earthquakes, long droughts, and torrential storms.

So they would appeal to their mountain gods for good will,

making offerings on the summits.

To study these sacred mountains, Johan Reinhard made more than 200 ascents

above 5,000 meters, in five Andean countries,

discovering more than 50 archaeological sites.

But in all of his expeditions, one site eluded him:

The temple of Ausangate, built to worship one of the Inca's most sacred peaks,

6,400 meters above sea level, nearly 100 kilometers from Cusco.

Ausangate is also visible from Lake Sibinacocha,

over 16 kilometers to the east.

According to the mythology, this temple was built in ancient times,

long before the Inca empire,

beside a large lake at the base of Ausangate,

by the people of the Vilcanota Valley.

The Incas conquered the Valley,

and the temple remained one of the most important in the region.

REINHARD: A great temple, that, to this day, nobody's found.

NARRATOR: To better explore alpine lakes, Johan helped pioneer the practice

of underwater archaeology,

and then brought it to the high mountains.

REINHARD: Scuba diving, at altitude.

NARRATOR: Johan reached submerged sites

that were previously beyond the limits of human exploration.

But to this day, he has not found the lost temple of Ausangate.

REINHARD: Feels like unfinished business.

Although I think Preston's kind of got that terrain... covered.

♪ ♪

NARRATOR: Preston begins to wonder

if the lost temple could be at Sibinacocha,

so he sets out to finish what Johan had started.

But first, he'll have to learn how to scuba dive.

SOWELL: I found a technical diver named George Watson, who is a cave diver.

When I told him about the project, he jumped right in and agreed to train me.

GEORGE WATSON: I've been diving since 1974,

and I'd done good deal of high-altitude lake diving here in Colorado.

NARRATOR: Diving at altitude is especially dangerous,

because the thin air creates a greater difference

between the atmospheric pressure above and below the water.

Without proper breathing mixtures and decompression,

this can lead to crippling pain, paralysis, and death.

SOWELL: It's all theoretical, the dive tables don't go that high,

so nobody really knows what happens to you.

WATSON: Diving at 16,000 feet is pretty much unheard of,

it's unique in the diving world.

NARRATOR: Add that to the thermal challenge of staying warm

in water only a few degrees above freezing,

and it becomes a very formidable undertaking.

REINHARD: The truth is, you're working at those altitudes blind.

SOWELL: Aah, this is such a bad idea.

(chuckles)

REINHARD: What Preston's done is exactly what should be done.

Taken a really more difficult and dangerous aspect of the research,

which is searching underwater as well.

♪ ♪

NARRATOR: After months of training,

Preston and George finally make it to Sibinacocha,

along with a team of world-class divers,

to examine the artifacts and explore deeper within the lake.

But the expedition ends in tragedy,

when a member of the team perishes during a world record dive.

WATSON: During the dive, something went terribly wrong.

NARRATOR: George and his dive partner, Geoff Belter,

are suddenly out of air and separated.

George shoots to the surface in an uncontrolled ascent,

expecting to die from decompression sickness.

His partner Geoff never surfaces and can't be recovered.

George survives, but his rapid ascent and failed decompression injure

his spinal cord, leaving him paralyzed from the waist down for nine months.

It would take three years of rehab to regain his strength.

SOWELL: I had a rough couple years after that, you know,

understanding I had some responsibility in this man's death.

NARRATOR: The memory has haunted Preston ever since

and given him a better reason than ever

to protect what is now his friend's final resting place.

♪ ♪

(flamingo trills)

NARRATOR: A year after the accident, Preston is back at the lake

to finally show his underwater discoveries to Peruvian archaeologists,

but this place carries a new weight for him now.

SOWELL: Geoff's body is right there.

I'm confident we won't have any more accidents,

but, um... I don't know if I have PTSD or what,

it's causing some... a little anxiety.

♪ ♪

NARRATOR: After dark, a local shaman performs

a special ritual offering to the gods of the area.

ARTURO RIVERA: It's called despacho.

This ritual will be like asking for

permission the Pachamama, to the Mother Earth,

and the sacred mountains here around Sibinacocha lake.

SOWELL: An offering to the Apus, to the local gods,

to help protect us as we work here,

and to show respect to Geoff who lost his life here last year.

♪ ♪

NARRATOR: The people who live around Sibinacocha

have been here for generations,

living off of the land...

and carrying on the Inca's beliefs, traditions, and language.

Severino Crispin has lived near Sibinacocha his whole life.

He's been the leader of this team of horse wranglers

since Preston's first visit to Peru.

SEVERINO CRISPIN (in foreign language): All villagers in this community

have a lot of respect for this lake.

It is not an ordinary lake,

do not approach without permission.

NARRATOR: Severino and the rest of the wranglers

still believe in the concept of sacred landscape--

that the gods and spirits live within the land,

resting in boulders and other natural features called Huacas.

This gives Preston and his team a direct link

to their ancestral knowledge.

PEDRO GODFREDO (in Spanish): No, no, it is always here.

NARRATOR: He tells Preston about the legend of Sibinacocha,

and what happened here, hundreds of years ago.

CRISPIN (speaking foreign language): By this lake there was a big town.

NARRATOR: According to the legend, there was once a large city

on an island, in the lake.

One day, an old beggar showed up at a wedding,

and called upon the lake to swallow the town.

CRISPIN (speaking foreign language): Boom!

There was an explosion, and the city had been submerged in the lake.

SOWELL: It really makes me wonder what's out there under the water.

♪ ♪

NARRATOR: The legend corresponds with a scientific theory for the lake,

that the water level rose sometime during the Inca empire,

due to a change in climate or natural disaster.

This would have submerged the shoreline,

including the artifacts that Preston discovered in the water,

which he is finally ready to show to Carlos Ausejo,

who will be the first archaeologist to examine them up close.

CARLOS AUSEJO: This is what I've been waiting for,

since the first time I talked to Preston about it, it's pretty exciting.

♪ ♪

NARRATOR: Under water, the pot appears intact,

perfectly preserved by the cold water and protected from looters.

Carlos also examines the golden, zigzagging, snake-like structure,

and at this point, is well convinced of the site's significance

and that the pot may have been left there as an offering

by Inca or pre-Inca people.

SOWELL: Good job, Carlos.

NARRATOR: But why?

SOWELL: You could really see its... its shape.

AUSEJO (speaking Spanish): I want to take it out.

(Sowell laughs)

♪ ♪

NARRATOR: The next step will be to recover the pot from the water...

SOWELL: It's so cold.

...carefully, and determine its origin.

AUSEJO: Well, we have a lot of work to do.

SOWELL: We have some boxes to check before we can claim

it's the temple of Ausangate,

but it fits with the legend and history of the site.

NARRATOR: They'll need permits to recover the pot, so that will have to wait.

In the meantime, they surround the pot with sandbags

to protect it until they can return.

SOWELL: The thing that really terrifies me now

is that we won't get this done in time.

NARRATOR: Constantino Aucca is a co-founder

of the Association of Andean Ecosystems,

and one of the first conservationists to visit Sibinacocha.

CONSTANTINO AUCCA: The lake of Sibinacocha is

one of the most important wetlands in the world.

NARRATOR: Constantino is most concerned about mining,

which has been edging closer and closer to the watershed.

AUCCA: From Patagonia to Venezuela, all the Andes, they are full of minerals.

NARRATOR: This region is very high in gold, silver, copper, and lithium,

but extracting these minerals would be devastating,

poisoning the Vilcanota River, the Inca's most sacred waterway,

which flows directly out of Sibinacocha,

feeding millions of people, and wildlife, downstream.

AUCCA: The landscape is going to disappear.

NARRATOR: Not only that, mining could destroy the cultural features

and natural history of the area, before it has been properly studied.

SOWELL: We have so much to lose if this place is destroyed,

but Peru has a law that will allow you to protect a cultural landscape.

So we're sort of in a race with the mining companies now to try to prove

that it is this sacred ceremonial site.

♪ ♪

(indistinct announcement over PA)

NARRATOR: Before Preston can return to Sibinacocha,

he must get through his next assignment:

to guide a scientific expedition to the far reaches of the Inca empire,

in the Atacama Desert of central Chile the driest place on Earth.

SOWELL: Part of why I'm going is to try to understand

this dedication to high places.

I think it will really help me understand what's going on at Sibinacocha.

♪ ♪

NARRATOR: The Atacama Desert is the home of the highest

archaeological site in the world,

created by the Inca 500 years ago.

Priests trekked, on foot, from their capital in Cusco,

almost 1,600 kilometers miles, to Mt. Llullaillaco,

near the edge of their known world.

They used their extensive road systems,

through some of the harshest conditions on the planet,

to climb this sacred peak and perform a special ceremony on the summit.

Hundreds of years later, Johan Reinhard traveled to Llullaillaco

to excavate on the summit.

His findings would become one of the most significant

archaeological discoveries in history.

REINHARD: We knew it was an important site because there were ruins at the base

and because there were ruins all the way to the top.

You're not gonna find that

unless there had been some kind of offerings made there.

NARRATOR: The Inca's climbing was far ahead of its time.

They were the first to use modern mountaineering strategies,

establishing camps at key points along their routes,

and braving the thin air to build ceremonial sites

on more than 100 mountains, above 5,000 meters,

the only society in history known to make offerings at that altitude.

In fact, no other culture in the world had reached those vertiginous heights,

and after the Inca, no one would reach

the summit of Mt. Llullaillaco until the 1950s.

♪ ♪

Preston is here to guide a team of microbial biologists

from the University of Colorado to their site halfway up the mountain.

But he has a secondary motive: to follow in the footsteps

of Johan Reinhard and increase his understanding

of how the Inca lived and died in the mountains.

♪ ♪

Preston and his team find life on the mountain challenging,

which makes the Inca's accomplishments here that much harder to conceive.

SOWELL: It's just hard to be here, much less work here.

NARRATOR: At Mt. Llullaillaco's altitude, towering over 6,000 meters,

altitude sickness can cause fluid to leak from blood vessels into the brain,

which can be totally debilitating and even deadly.

So what could have compelled the Inca to make such an arduous pilgrimage?

When they climbed this peak 500 years ago,

they likely thought the effects of the altitude were symptoms

of the mountain gods expressing their influence,

and climbed through the pain, to the very summit,

where they performed their sacred ceremony of human sacrifice.

In 1999, Johan ascended the Inca's path to the summit

and made an archaeological discovery like no other in history.

A ceremonial platform, ritual offerings, and three perfectly preserved mummies,

aged six, seven, and 15.

The Inca selected the children for their beauty,

from all corners of the empire,

who accepted their sacrifice as a great honor,

to go and live forever with the gods.

♪ ♪

Human sacrifices were sometimes executed by strangulation,

a blow to the head, or as in this case, they were drugged and buried alive.

ARCHAEOLOGIST (off screen, in Spanish): Look at the little hand.

The hand, Johan.

REINHARD (in hoarse, whispering voice): As you can see, the hands, the arms,

you can't see the legs, but they're very well preserved.

It was a powerful moment for me.

You have this feeling like you've just snapped back in time.

You could turn around and see an Inca priest,

you know, it's that kind of feeling.

NARRATOR: Although this practice seems horrific today,

human sacrifice was essential to the Inca,

and Johan's discovery provided a major breakthrough

in our understanding of their mountain worship,

adaptation to altitude, and Inca genealogy.

And even though Preston did not reach the summit,

he still felt the profound effects of Mt. Llullaillaco's thin air

and gruesome history.

SOWELL: I certainly came down with a better perspective on mountain worship,

and sort of a renewed respect for these people

that saw these landscapes as sacred.

It just reaffirmed what I already believed about Sibinacocha.

♪ ♪

NARRATOR: Leaving Mt. Llullaillaco, Preston drives past a Chilean copper mine,

one of the largest in the world, which gives him the idea

of the environmental devastation caused by mineral extraction.

SOWELL: This can't be allowed at Sibinacocha, absolutely not.

(truck alarm beeping)

♪ ♪

NARRATOR: Back in Peru, Preston has returned...

-How are you? -(man laughs)

...to finally recover the ceramic pot,

from the freezing water of Lake Sibinacocha.

But that's not all, he's joined by George Watson,

who spent the last three years rehabilitating his legs,

so he could return to that fateful site and help with the recovery.

WATSON: I've done an awful lot of rehab and a lot of training,

with one goal in mind and that was coming back.

NARRATOR: And this year, they aren't taking any chances.

SOWELL: There are a few things I want to go over just to get us started...

NARRATOR: They've assembled a crack team of divers to assist in the recovery.

SOWELL: These guys have been my dive mentors

since I had to learn to dive to do the work up here.

NARRATOR: The team also includes archaeologist Martin Polo,

and conservation specialist Alexandra Gambetta,

who will manage the recovery of the pot once it is out of the water,

and look for ceremonial offerings,

which were often placed inside ceramic vessels.

ALEXANDRA GAMBETTA: What is inside? We don't know.

That's what we are going to find out.

♪ ♪

NARRATOR: On the hike in to Sibinacocha,

emotions are running high,

especially for George.

-SOWELL: Welcome back. -WATSON: Thank you for that.

(Watson sighs)

-SOWELL: You walked in. -WATSON: Yeah.

Thanks for giving me the opportunity.

-Thanks for believing I could. -SOWELL: Yeah.

WATSON: It's beautiful. It's like I remember.

♪ ♪

NARRATOR: The next morning, the dive team prepares their equipment

for the pot recovery.

They make a plan that involves each member of the team:

to transfer the pot to a basket,

and transport it with a lift bag to the shore.

And their work must be impeccable:

one mistake could cost them dearly

and damage this one-of-a-kind piece of history.

♪ ♪

♪ ♪

Below the surface, George and Preston think of their friend, Geoff,

who cared so much about protecting this place.

First, Preston leads the divers to the pot,

and removes the sandbags they placed to protect it from weeds.

SOWELL: To my relief, the pot looked untouched, it was intact,

and then the next team took over.

NARRATOR: As they transfer the pot to the basket,

sediment from the lake bottom is disturbed...

SOWELL: By that time, visibility was almost zero.

NARRATOR: ...but they are prepared for that.

Momentarily blinded, George pulls out the lift bag,

secures it to the basket,

and just as planned, the pot floats off the lake bottom,

moving for the first time in hundreds of years.

♪ ♪

♪ ♪

-(water burbling) -(horse whinnying)

GAMBETTA: Wow.

-FELIPE (laughing): Ah! -SOWELL: Hey!

FELIPE: Yeah. (in Spanish): Un photo, un photo!

♪ ♪

SOWELL: Been a long time coming.

I learned how to dive just to go down and prove what that pot was,

what this place was.

Pretty profound feeling.

(sighs)

♪ ♪

NARRATOR: For George, it is an incredible catharsis,

coming full circle on the thing that brought him to this lake years ago.

And for Preston, he can finally sleep,

knowing that this important artifact will get the attention it deserves.

SOWELL (off screen): I need bigger tweezers.

NARRATOR: Back at camp, examination of the pot begins immediately,

to remove the sediments for analysis, clean the ceramic,

and finally see what, if anything, is inside.

MARTIN POLO: This in Peru is the first time we can recover

an intact pot from a submerged area.

NARRATOR: Digging out the sediment,

Alexandra feels something solid within the pot.

GAMBETTA: It feels like a stone or something.

NARRATOR: Offerings could tell Alexandra and Martin

why the pot was placed underwater.

GAMBETTA (off screen): I've never seen something like this.

NARRATOR: She unearths the pot's unusual contents:

three polished stones, which Martin believes are ceremonial.

POLO: I'm guessing it's an offering to the lake.

GAMBETTA: I've seen pots with leaves,

organic material, textiles, offerings,

but never with three stones inside of the pot.

It's... It's fantastic.

NARRATOR: Expert analysis reveals that the pot is 600 to a thousand years old,

and archaeologists believe that this vessel, and the stones inside,

were part of an offering, supporting the theory

that this site did indeed have ceremonial significance.

♪ ♪

With the recovery complete, Preston has one more goal to accomplish,

so he moves the team around the lake, to the base of Yayamari,

the sacred mountain that looms over Sibinacocha

like an ancient pyramid, to conduct a survey from the summit.

Before long, a peculiar storm blows in,

bringing snow, hail, thunder and lightning.

Weather events were seen as acts of the gods by the Inca,

and thunder was how the mountains communicated with one another.

SOWELL: You can see how vulnerable you feel up here in the mountains,

and how profound lightning must have been

if you didn't understand what that was and what was causing it.

NARRATOR: It is an ominous welcome to their camp below Yayamari.

NARRATOR: The next morning, they head up the mountain for their summit attempt.

SOWELL: Our goal is to survey the landscape,

take a better look at how all the landscape features might fit together.

NARRATOR: As Preston climbs, he starts to notice certain geographical features

aligning in ways he hadn't seen before--

alignments that were only now becoming clear to him,

but must have been obvious to the Inca.

SOWELL: The juxtaposition of that landscape with mountains,

with celestial bodies, with the rising and setting of the moon

and the sun and stars at certain times of the year,

the glaciers, the lake, the rivers, it's all right there.

NARRATOR: Suddenly, he realizes that perhaps the temple

he had been looking for all these years was there all along,

composed of the landscape that surrounds him.

For Preston, nothing could be more sacred.

But the team has one more revelation waiting for them,

something tangible, that could tie everything together.

During the descent of Yayamari,

they arrive at what looks like the ruins of a large complex.

-POLO: An Inca structure. -SOWELL: You think it's Inca?

POLO: Yeah, because there are like four or five rectangular buildings

around a patio, a central patio,

and the buildings around it are often sacred places.

NARRATOR: Martin describes how the Inca would conduct

ceremonies in plazas like these,

using the different rooms to prepare offerings for the gods.

POLO: Maybe here were some stairs.

Just using the imagination, the rock kind of looks like it was shaped

to be the same as Yayamari.

NARRATOR: Location was very important for the placement of ceremonial sites,

and this new complex is directly below Yayamari,

with a direct view of Ausangate,

making it an ideal place to worship the mountains.

Boulder fields like this were often considered sacred on their own,

and used as the groundwork for larger ceremonial centers,

built into the landscape.

SOWELL: It's just perfect for a site like that.

POLO: This could be like a temple.

♪ ♪

REINHARD: It does look like there's a base of an Inca complex near the lake,

but whether it is the temple of Ausangate,

it still seems unclear to me.

SOWELL: Everyone wants to excavate there to gather

more data on what that complex could be.

NARRATOR: At the end of this expedition,

Preston has fulfilled the dream he's had for so many years,

but he's created some new ones, so his work is not done.

SOWELL: All of the effort just to bring this thing up,

and the prices that we paid.

I think it's another magic piece in the puzzle

that is Sibinacocha and that watershed.

But we're not there yet.

Mining companies could apply for new permits tomorrow.

♪ ♪

NARRATOR: Before long, Preston returns, yet again,

to help with the archaeological excavation of the Yayamari complex.

The stakes for this expedition have never been higher,

and for Preston, it is somewhat bittersweet.

He is finally passing the torch to archaeologists who will take the lead

in determining the past and future of Sibinacocha.

Six archaeologists from all over the world are led by Arturo Rivera

to the Yayamari site and get to work immediately.

RIVERA: Each time we walk by, we can find something new.

NARRATOR: He is joined by his wife, Sarah Baitzel,

a mortuary archaeologist from Germany.

SARAH BAITZEL: It really gives you the sense of an archaeological Disneyland.

This is a site where you can spend many, many years digging.

SOWELL: Now we've got academic archaeologists involved

that are best qualified to manage this thing going forward.

NARRATOR: They find signs of habitation by Inca and pre-Inca people,

who adapted dwellings and ceremonial structures

to the landscape beneath Yayamari, including irrigation canals,

and modification of sacred springs and boulders.

SOWELL: These sites were placed in juxtaposition

to the mountains and the natural features around them.

REINHARD: That verifies to me that it was an important Inca site.

So there's no doubt that the lake was considered sacred,

SOWELL: I'm so excited right now.

BAITZEL: This is a place that's sort of drawing people to it.

The landscape is alive.

RIVERA: It's a place that has to be protected.

It's part of our past as Peruvians.

POLO: It's our history, our heritage.

NARRATOR: With the archaeology underway, Preston is free to return

to his study of the Sibinacocha habitat.

He treks around the lake to retrieve camera traps,

which he hopes have captured photographs of the endangered Andean mountain cat.

SOWELL: The Andean mountain cat is the most endangered cat in the Americas.

NARRATOR: He finds historic photographs of the elusive cat,

proving for the first time that it lives in the watershed.

SOWELL: That will act as an ambassador species for the ecosystem,

and help us protect the area.

NARRATOR: Preston knows better than anyone

how much there is to protect at Sibinacocha:

the history, the wildlife, and the people that live here and downstream.

And now, with the archaeological findings,

photographic proof of the Andean mountain cat,

and everything that is still left to discover,

Lake Sibinacocha is on the verge of being protected as a sacred landscape.

♪ ♪

REINHARD: I think what distinguishes sacred landscape from landscape

is that it's come alive for the people.

SOWELL: It's so encouraging that an entire culture,

an entire people can see the world that way, and I think

it gives me some optimism for the rest of the world.

NARRATOR: And as for the lost temple of Ausangate,

they've got more work to do.

REINHARD: You know, it's still left to be determined.

NARRATOR: For now, Preston's search at Sibinacocha continues.

And he may never know if this really is the lost temple,

but if he can at least protect it for the future, anything is possible.

♪ ♪