- Rope!

- [Narrator] Tonight on this "Oregon Field Guide" special.

- Good.

- We join Earthfix on Mount Hood for a breathtaking expedition under Mount Hood's Sandy Glacier.

(gentle music) - You know, it's just kind of a reflection of how life works sometimes, that you find something of this magnitude, that we now have found the largest glacier cave system in the lower United States.

- [Eddy] As soon as I came in, I was hooked.

(gentle music continues) - [Brent] He found two tubes.

So we're gonna go see where it goes.

- [Eddy] Doing something that no one's ever done.

- [Explorer] Rock!

- It probably is the driving force of professional cavers.

Big fracture when I did that.

This is dangerous, caving.

There's just no room for error.

- [Kara] It's history, it's science, it's beauty, it's everything.

(water pattering) (static crackling) (bright music) (water sploshes) (bright music continues) (birds cawing) - [Explorer] Just go ahead (indistinct), do a radio check there.

Make sure... (gentle music) - [Narrator] It's a mountain climbed by over 10,000 people a year, a mountain that lies just an hour's drive from Oregon's largest city.

And yet Mount Hood has a secret.

- I've been caving since 1986.

This is definitely the most memorable caving project and adventure project I've ever done.

Let's come up around this way.

You see this in Europe, Greenland, Alaska.

To find something in Oregon of this size and magnitude, I wouldn't expect that.

- [Narrator] What Eddy Cartaya and his partner Brent McGregor discovered is a hole in the Sandy Glacier.

It drops 150 feet through the ice.

It's called a moulin, and it leads to over a mile of caves and passages inside the glacier.

(gentle music continues) - Rope!

- [Narrator] It's the kind of hazard that would scare most mountaineers to death.

- Good.

- But Brent and Eddy are explorers, here to continue a mission they began in 2011.

Their goal is to find new passages and to be the first to map what may be the largest glacier cave in the lower 48 states.

- [Brent] All right, this is load tested.

- [Narrator] But to explore here is to face rockfall and potential ice collapse in one of the most dangerous environments on Mount Hood.

- Okay, you're good.

- All right.

- Don't worry about me.

I'll adjust to you.

Every minute counts.

(dramatic music) - [Brent] Good.

This moulin is very intimidating.

- [Kara] No worries.

- [Brent] There's nothing like it we know of in the Pacific Northwest.

So, going down in, it humbles you.

You're like a little ant in there.

- [Eddy] This is top station, what you got?

- [Explorer] Everything's good.

You can come down.

It's un-friggin-believable.

It's changed tremendously.

You won't even recognize it.

- [Narrator] Eddy plunges down the throat of the moulin into a cave he and Brent call Pure Imagination.

- [Eddy] It's definitely grown its size.

It used to be more vertical.

- Our first discovery of it, it was probably 25 feet in diameter, and now the thing is just blowing out of proportion.

- [Narrator] A small team joins Eddy and Brent 15 stories beneath the surface of the glacier.

From here, they'll navigate tunnels carved by freezing whitewater and framed by walls of sculpted ice.

- [Brent] Wow.

- [Narrator] This is where their weeklong expedition to survey, map, and photograph the caves begins.

(water sploshing) [Brent] There's something really magical and beautiful about this unknown, pristine area that I'm just really attracted to.

(explorers chatter indistinctly) It's just hard to believe that there's wild places out there that nobody's stepped foot on.

- [Narrator] For science, the expedition is a chance to see inside a glacier that's half the size it was just a century ago.

For the expedition, it's a chance to go somewhere no one else on earth has gone.

(water pattering) - [Eddy] Man, that is cool that it's happening.

A new pit forming.

It's like a new cave every year.

It's crazy.

(bright music) - [Narrator] The caves beneath Mount Hood's Sandy Glacier likely formed only recently.

They exist inside a relatively small glacier on the mountain's west side.

Brent and Eddy identified three distinct caves beneath the ice: Frozen Minotaur, Snow Dragon, and Pure Imagination.

They've mapped a mile of passages that reach like fingers of a hand into the glacier.

There may be more caves here, but getting to them is half the effort.

- You ready to go now?

- Ready to go.

- Okay, let's pack up and get.

(explorer groans) - [Eddy] It took over a year to plan this expedition.

So you can build a house in less time.

(explorers chuckle) As we learned there was more and more up here that needed to be done, we first conceived of an expedition, right away, the thought was, "Okay, we've got to get help."

- [Narrator] This expedition gets support from the National Speleological Society, but the heavy lifting is done by Brent and Eddy's friends in the search and rescue, caving, and mountaineer communities, friends willing to spend up to a week at what's been dubbed Camp Tenacious at 6,400 feet on the Sandy Glacier.

[Sean] Put the desk over here.

We'll come in here for the occasional massage.

I like this corner over here.

This is where we're gonna put the lounge.

[Kara] People come in and they're kind of awestruck, kind of in an environment, where am I?

What's gonna happen?

How's it gonna work?

I love that part.

The secret is to not push down too hard because there's a really sharp point on the end of the ice ax.

So we put a hole in the bottom of the bucket, we have no food.

You get here on Saturday and there's no stopping.

The objectives need to be met.

The logistics have to be covered.

There's just not time for sleep.

- [Dispatcher] Tomorrow night, still a 20% chance of showers until 11:00 p.m.

- [Explorer] Thanks a lot.

Camp Tenacious out.

- [Narrator] Camp isn't luxurious, but it is convenient.

A hundred yards away is a massive cave known as Snow Dragon.

It was this cave noticed by hikers as early as 2009 that first got Brent's attention.

He'd been searching glaciers for years, trying to find a cave like this.

[Eddy] Brent is the one that first emailed me and tells me, "Hey, I," he found this YouTube video some hiking group did.

It didn't show anything except for them just piddling around the entrance in daylight.

So as soon as I saw that, I said, "Well, we gotta go."

So we spent a day looking for it, didn't find it.

The next morning, we came out and found a little crevasse.

Nothing like what it is right now.

- High five.

(Eddy chuckles) We made it.

- We made it.

- [Brent] And there it is.

That is one big hole.

- Oh, it's a monster cross.

[Eddy] And as soon as I came in, you know, I was hooked.

Being inside of ice like that, I'd never been in anything like that.

- [Narrator] Over the next several trips, Eddy and Brent brought back an arsenal of specialized caving gear, and as they probed deeper, they discovered two new caves, which they named Frozen Minotaur and Pure Imagination.

- Watch out, rock!

- Rock!

- You okay, Brent?

- Yeah, I've been better.

- [Narrator] The two explorers made an interesting pair: Brent, a free-spirited photographer and woodworker, and Eddy, a forest service law enforcement officer with deep military and search and rescue experience.

Since they met, they've mounted nearly every expedition together.

[Brent] Anything I basically dare him to do, he'll do if he knows he's not gonna die doing it.

[Eddy] At this point, I think we know how to read each other.

We know what needs to be done.

I don't know to describe it.

We just clicked.

- [Narrator] But for the two veterans of rock caves and lava tubes, the glacier caves were unfamiliar territory.

The dangers of navigating beneath hundreds of feet of unstable ice became real as they looked for an exit to a cave they called Pure Imagination.

[Brent] All right.

[Eddy] We knew the lower entrance had snow on it, but we figured that it was very thin and that we'd be able to probe our way out.

And if it didn't work, that we would just go back out and climb the ropes up the pit.

However, the sunlight lit up the pit and it released showers of rocks coming down and made it totally unsafe.

So we were kind of stuck.

- [Narrator] The expedition was trapped inside a cave the rest of the world didn't know about.

The only way out was to dig.

- [Brent] We got seven feet of digging to get out.

- [Eddy] It's like "The Great Escape."

This is gonna take a long time to get out.

(ice pattering) Climb out the top.

Everyone started getting cold.

Really, really cold.

You could start to see it, shivering and starting to stare.

- [Narrator] Eddy returned to face the dangerous rockfall at the moulin so that he could try to dig the team out from the surface.

[Brent] Half of the group, when we decided let's dig this out, they wanted nothing to do with it.

So they said, "We're gonna go back up and climb out the moulin.

You guys can stay down there and die if you want."

So there's four of us, I believe, that stayed.

- [Brent] Getting your money's worth today.

- [Explorer] Oh, yeah.

- [Brent] Just keep digging out.

[Eddy] You have an hourglass going on once you go in there.

You can only be in there a certain amount of time before you get hypothermic and start making stupid mistakes.

- [Brent] We've been in this cave for a couple hours and we finally broke through.

Ah, we're not far.

We're almost out of prison!

- Do it!

(explorer cheers) - [Brent] Definitely getting cold.

Eddy!

- [Eddy] And it took a long time, even with us digging from the top and them still digging from the bottom.

- [Brent] Give me a hand.

All right, front door.

- Woo-hoo.

- [Eddy] There was no question that there was a little bit of anxiety (chuckles) going on with that incident.

(gentle music) - [Narrator] Danger exists on every trip to the caves, but the reward is the possibility of discovery.

Tomorrow, the team will pursue what may be a new passage inside Snow Dragon.

(explorers chatter indistinctly) As morning arrives at Camp Tenacious, the team prepares to spend hours under the ice in search of a new passage.

- Okay, pack up some gear.

- Objective is to climb up to that hole, and then if it looks like it's passable, we can get a few people in there and try to survey that into the map.

- [Kara] Okay, breathe out.

Breathe out some more.

(Brent groans) - [Narrator] Snow Dragon itself isn't far from camp, but the unexplored passage is 30 feet above the ground.

To get there, Eddy will have to cope with some of the most challenging climbing conditions he's ever faced.

- [Eddy] I'm only gonna go as far as I can reach.

- [Explorer] Come on.

(bright music) - All right, this just pulls and it stops.

It's like a self-winch.

- [Brent] That looks good.

- Well, call it.

If you think it gets stupid, we'll just stop.

The cavers, they're obsessive.

It's an obsessive subculture.

But if there's a possibility of getting into a new passage or finding a new cave or surveying a new cave, that'll suck a caver in.

They'll quit work, not go home for days, do whatever they can do to get there and be the first one to experience it and document it.

But the underlying force of caving is discovery.

These little passages can lead to other caves.

Frozen Minotaur was found by following a pretty uninviting looking water passage and it led to a whole new cave.

So, we just don't know until we get up there and see.

It could lead to something big.

(bright music) (water pattering) Let me down close!

- [Barb] I am Search & Rescue and I understand the systems.

I know the safety factors.

I take risks myself.

I think you saw that I still was a little nervous.

- [Eddy] This is dangerous caving.

There's no question about that.

(bright music continues) There's just no room for error.

Not gonna work.

- [Brent] The first thing I thought was, "This is an amazing part of the story.

The second thing is, "I'm belaying my partner and his life could depend on what I do."

All I can do at that point is give him my 100% attention.

- [Eddy] Huge fracture.

- [Brent] What's that?

- [Eddy] Big fracture when I did that.

- You become one team, you know?

It's not you and him.

You are there to do this thing, and so neither of you will fail.

(ice squeaking) - [Narrator] After nearly three hours, Eddy and Brent find two new passages extending about 30 feet through an icy crawl space.

(rocks clatter) They map the new passages even though they don't lead to a new cave as they'd hoped.

- [Brent] Here is the hole going back out to the cave.

Here is the way we came in.

- [Eddy] That's part of exploration is to push leads, see if they go.

Sometimes they don't and, you know, that's the end of that, and other times they do and it pays off.

- [Narrator] The work doesn't stop with one dead end.

- [Eddy] Well, the waterfall's gonna screw it up.

Come off to the side a little bit.

- [Narrator] Brent and Eddy continue their survey through the rest of Snow Dragon.

They've each been here over a dozen times to gather raw data for maps like these.

(water pattering) - [Eddy] 14 1/2 degrees elevation.

- [Narrator] But unlike limestone caves or lava tubes, glacier caves are unstable and constantly changing.

Walls collapse and new channels are carved by water pouring in from both above and below.

Year over year, these caves are getting larger.

What Eddy and Brent's surveys show is that this is a glacier disintegrating from the inside out.

- [Brent] (chuckles) 89.7.

- [Eddy] All right, got it.

So, actually, this new passage wall actually comes wide.

They're gonna disappear just like the Paradise Ice Caves did.

Those were wonderful places.

They don't exist anymore.

That's the other neat thing about documenting these caves.

You're documenting history.

- [Narrator] The Paradise Ice Caves were on Mount Rainier.

What happened there could be a sign of what's to come for the Sandy Glacier caves.

(gentle music) In the 1950s, people came from all over the world to visit the Paradise Ice Caves and Lou Whittaker was their guide.

- [Lou Whittaker] They were the number one attraction at the start of our guiding.

Tours came from all over the country in those days.

The entrance was always a little dangerous.

You had to watch for falling flakes of snow and ice.

- [Historic Footage Narrator] Flares light the way through a glittering wonderland of ice.

(bright music) - [Lou] And you'd bring the group in until it's just about dark, listen to the oohs and ahs.

- [Narrator] A survey in 1978 showed eight miles of tunnels through the ice.

- [Lou] As the summer progressed, you'd get the blues and greens of the sun coming through the ice caves.

- [Narrator] Those beautiful colors were a bad sign.

It meant the glacier was getting dangerously thin.

The caves started to collapse.

(bright music continues) - [Lou] As I saw the ice caves retreating each year, I knew that eventually they were going to be melted out and no longer there.

We are in a warming period and times are a-changin'.

(water sploshing) - [Narrator] The valley where the ice caves used to be looks like this today.

What happened at Paradise is something that's talked about a lot on the Sandy Glacier expedition.

Eddy and Brent are seeing the same process unfold here.

The only way to understand it is to measure these caves every year and calculate how much ice is melting so scientists can see what's going on inside the glacier as it retreats.

- [Kara] Dinner's ready (indistinct).

- [Narrator] Tonight, the goal is to measure how much larger Pure Imagination is getting.

- [Eddy] The objectives for tonight again, are to survey the moulin shaft.

It'd be nice if we could start hiking up at about 10:30.

It could be up to two hours of rigging, but it's gonna be a long one.

(bright music) (wind whistling) (explorers chatter indistinctly) - [Brent] There's a lot of things happening.

A glacier's always moving.

It's always changing.

We never know what we're gonna find the next trip up.

- [Eddy] Go below it, down the ball line.

- [Brent] It's past my bedtime.

It's 11:40.

So we may get out of here before the sun comes up.

(Brent chuckles) - [Eddy] Go back on line two.

- [Narrator] Eddy and Brent hoped the ice would've hardened by this time of night, but meltwater rains into the pit.

- [Brent] Rock!

- [Narrator] It's one part of a process that's transforming the moulin.

- [Eddy] These are rivers of ice.

They don't flow as fast as river.

You can't see them moving.

But make no mistake, they are rivers.

21.3.

- 21.3.

26.3.

22.8.

- [Eddy] To really study and appreciate what's going on here and kind of piece together what's going on with the glacier, you have to make repetitive maps and surveys.

We are creating the only record of them.

These maps we're generating are becoming history, and when these caves are gone, which they will be, just like Paradise Ice Caves, this will be the only remnant.

The photos, the videos, and these maps will be the only documentation.

- It's amazing.

Where else can you look at that?

I mean, I never get tired of it.

I could stay in here all day.

I could live here.

- [Eddy] 65.5.

- [Brent] Yes.

- [Narrator] Neither Brent or Eddy are scientists, but they're adding to the scientific record in a way few others can as not many people have the skills or desire to work in a dangerous place like this.

- [Brent] We've been monitoring these caves for a little over two years now.

We take atmospheric readings, water and air temperatures.

What is the wind?

What is the humidity?

All these different measurements.

And it's changing.

It's dramatically different from one section of the cave to another.

- [Narrator] Photos reveal a moulin opening that's widened by 36 feet in two years.

Eddy says the volume of the moulin itself has increased by 400% in just one year.

It's a loss of ice that's never been recorded until this expedition.

- [Brent] We just finished our survey at 3:09 in the morning.

So the survey was from the top of the glacier down the moulin hole to the bedrock floor.

So now that we're done, we've gotta ascend the rope to the top, climb down a steep slope to our tents, and go to sleep.

(wind whistling) (Amelia chuckles] - I hear you got dropped down a hole last night.

- [Eddy] I did.

- [Narrator] Over the last several years, the expedition has given scientists plenty to chew on.

They've tested the water and identified cave-adapted species like this ice crawler.

They found mallard feathers in ice that may be hundreds of years old as well as noble fir seedlings seen sprouting in near total darkness.

But the big question on everyone's mind is why are these caves here and why now?

- So I'll lead in and just... - [Narrator] To answer that question, Brent and Eddy invited Dr.

Andrew Fountain, who studies glaciers around the world.

- [Dr.

Andrew Fountain] We resurveyed part of this yesterday to get the new height and the widths and we also ice climbed up into that hole.

[Eddy] see this in other places in Greenland?

of this size or what?

- [Andrew] Oh yeah, sure.

In Greenland.

- [Eddy] Alaska?

- [Andrew] Alaska, yeah, you'll get places like this.

Yeah, we've seen this in other glaciers where you get a little tube, you know, the size of your finger and that kind of snakes its way through the ice.

And then as more water goes through it, it begins to enlarge and enlarge and then it turns into something like that.

I think it's one sign of a dying glacier.

That's just kind of my gut sense of it.

Wow.

- [Narrator] Andrew says the force that created these spectacular caves is friction.

The Sandy Glacier isn't very cold.

None of the glaciers in the northwest are.

All this ice is already at its melting point, 32 degrees.

(water sploshing) - [Andrew] So when you have meltwater moving down into the ice, the friction of that water against itself creates a little bit of heat, then it begins to enlarge the passages.

- [Narrator] In winter, the weight of the glacier would normally crush the cave passages, but that's not what's happening on the Sandy.

- It's the thinner ice caused by climate change that allows these caves to grow really big because you don't have the really thick ice above it squeezing it shut.

So with very thin ice above it, these caves can expand through these melting processes of warm air temperatures and water flowing through.

(water sploshing) - [Narrator] Nearly every glacier in the Northwest is losing ice.

Andrew's archive of photos shows the dramatic retreat of Cascade glaciers over time.

- [Andrew] We would probably be under 200 feet of ice sitting here in 1900.

- [Narrator] What Andrew's photo studies don't show is what's happening inside retreating glaciers.

- [Andrew] It's impressive, yeah, it's huge.

I've never seen anything quite like it.

A little cavern in a little glacier, no big deal.

But something this big, that's unusual and probably very significant.

- [Narrator] The Sandy Glacier caves reveal ice loss that was previously invisible.

- [Andrew] Well, I think this is currently an unexplored area in understanding how much mass these glaciers are losing.

We can make measurements from the surface by satellites, by lidar, by surface measurements.

Nobody's looked at what's happened underneath the glacier.

The fact that they're mapping the change of these caverns and particularly the size, that's what's scientifically interesting.

(water sploshing) - [Narrator] There's a consequence to losing glacial ice.

Paul Kennard studies how landscapes change after glacier's retreat.

He tracked what happened after the disappearance of Mount Rainer's lower Paradise Glacier and its once-impressive caves.

- Paul Kennard There's quite profound effects and I think the first main thing people will notice is the flooding, flooding getting worse and more frequent.

- [Narrator] The glaciers on Mount Rainier are now melting about six times faster than they did in the last century.

The mountain has lost about a third of its ice in just 100 years.

With so much of the glacier gone, the mountain itself is starting to crumble.

- [Paul] As they retreat, they leave a lot of sediment and dirt piled very loosely on very steep slopes and those areas really cause a problem because they can send landslides for miles.

- [Narrator] During one 2005 flood, heavy rains blasted away the loose soil and rock on Rainier like a fire hose.

- [Paul] We're getting flooding because the rivers are literally filling up with all the sediment that's coming off the glaciers.

(water sploshing) - [Narrator] It's a problem that could one day face the Sandy Glacier as well.

That's one reason Brent and Eddy do what they do, to add to a time capsule that says to future generations, "This is what was happening and this is what it looked like."

- [Eddy] I think we're gonna see new things developing faster and more often.

I mean, in one way it's exciting 'cause it means when we come back, we'll be able to document bigger and more frequent changes.

On the other hand, I would hate to see these caves collapse and disappear 'cause then it's kinda like losing a friend.

- [Narrator] These unstable caves aren't for everybody.

Collapsing snow tubes and similar features on Mount Hood's glaciers have killed people.

But for those on this expedition who have the skills, a chance to go somewhere unexplored within sight of a major city is something that doesn't come along every day.

(water sploshing) - [Brent] I'm really trying to get things that I've been working towards but haven't quite achieved yet.

(bright music) - [Kara] I love having a reason to slow down.

Is it gonna work?

You look at what life is there, you look at what formations are there, and you come around a corner and you're in this passage of beautiful parts of the earth that nobody's ever seen before.

(bright music continues) - [Narrator] wo leading national caving organizations confirm this is the largest known glacier cave system in the lower 48 states.

- [Brent] 90.4 feet.

- All right, that does it for our Snow Dragon entry survey.

- [Narrator] Just a few months after this expedition, Brent and Eddy returned to the Sandy Glacier and spotted this.

It's a new fourth cave they never noticed before.

It's still unexplored.

- [Brent] You know, it's just kind of a reflection of how life works sometimes, that you find something of this magnitude.

To me, this is my once in a lifetime dream come true: to combine my love for caving, for mountaineering and photography.

I will never have a chance to better this.

God damn, brother.

(water sploshing) (water sploshing continues) (water sploshing continues)