All language subtitles for Secrets.of.the.Underground.S02E06.Mystery.of.the.Ice.Cave.1080p.AMZN.WEB-DL.DD+2.0.H.264-playWEB_track3_[eng]

ON THE SHORES
OF LAKE MICHIGAN,

A POPULAR BEACH
SWALLOWS UP A CHILD...

...WITHOUT ANY
SCIENTIFIC EXPLANATION

FOR HIS SUDDEN DISAPPEARANCE.

I HAVE NEVER SEEN ANYTHING
QUITE LIKE THIS BEFORE.

WHAT COULD POSSIBLY CAUSE
SUCH A TERRIFYING INCIDENT,

AND ARE OTHERS STILL AT RISK?

WHOA.
WHOA, WHOA, WHOA, WHOA.

HOLY MOLY.

AND IN RURAL PENNSYLVANIA,

A BIZARRE ICE CAVE UPENDS
THE LAWS OF NATURE...

THIS IS REALLY UNUSUAL.

...MELTING IN THE WINTER
AND FREEZING OVER IN THE SUMMER.

THIS IS REALLY COLD.

WILL OUR HIGH-TECH TOOLKIT...

ARE YOU GUYS READY?

...FINALLY SOLVE
THE CENTURY-OLD RIDDLE?

WHOA!

IT'S DEFINITELY
AN ACTIVE PIT.

BURIED DEEP BELOW
THE EARTH'S SURFACE,

THERE ARE COUNTLESS
UNSOLVED MYSTERIES.

AND TODAY, WE FINALLY HAVE
THE TOOLS TO UNLOCK THEM.

THAT'S AMAZING.

IT'S SUPER DEEP!

I'M ROB NELSON,
A SCIENTIST AND EXPLORER

INVESTIGATING
OUR PLANET'S HIDDEN DEPTHS.

- GETTING DEEPER.
- HOLY MOLY, STEFAN.

AND HELPING ME UNCOVER
THESE SUBTERRANEAN SECRETS

IS TECH SPECIALIST STEFAN BURNS.

OH, MY GOD.
LOOK AT THAT!

TOGETHER...

I GOT SOMETHING!

...WE ARE UNCOVERING
NEW LEADS IN OUR QUEST

TO SOLVE EARTH'S
MOST ENDURING MYSTERIES.

- THERE WE GO.
- WHOO!

THESE ARE THE SECRETS
OF THE UNDERGROUND.

- Captions by VITAC--
www.vitac.com

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

ON THE SOUTHERN SHORE
OF LAKE MICHIGAN...

...SITS A UNIQUE NATURAL OASIS,

INDIANA DUNES
NATIONAL LAKE SHORE.

ARE WE GETTING CLOSE,
STEFAN?

YEAH, JUST KEEP
GOING STRAIGHT.

WHAT'S DRAWN STEFAN AND I
TO THIS 15,000-ACRE COASTAL AREA

IS THE PRIDE OF THE PARK,

A 126-FOOT SAND DUNE RISING OFF
THE BEACH CALLED MOUNT BALDY.

IT'S ON THIS GIANT SAND
FORMATION THAT A FREAK ACCIDENT

CHANGED A FAMILY'S LIFE FOREVER.

IT'S A SITE WHERE SOMETHING
REALLY UNUSUAL HAPPENED.

A 6-YEAR-OLD KID FELL
INTO THE DUNES,

SWALLOWED UP BY THEM.

THE BOY WAS ON A FAMILY
CAMPING TRIP,

BUT DURING A CASUAL HIKE
UP THE DUNE WITH HIS FATHER,

HE SUDDENLY VANISHED.

THE ONLY EVIDENCE
OF WHERE HE'D GONE

WAS A 12-INCH
DIAMETER HOLE IN THE DUNE.

LOCAL AUTHORITIES
WERE QUICK TO RESPOND

AND STARTED DIGGING
WITH SHOVELS, BARE HANDS

AND ANYTHING ELSE
THEY COULD FIND.

AFTER A 3 1/2 HOUR SEARCH,

THE BOY WAS FOUND ALMOST 11 FEET
BELOW THE SURFACE WITH NO PULSE.

HIS PARENTS PREPARED
FOR THE WORST,

BUT REMARKABLY, DOCTORS
WERE ABLE TO REVIVE HIM,

AND 2 WEEKS LATER,
HE WALKED OUT OF THE HOSPITAL.

BUT TO MAKE THE TRAGIC EVENT
EVEN MORE TERRIFYING,

NO ONE WAS ABLE TO EXPLAIN
WHAT EXACTLY HAD HAPPENED,

HOW A PUBLIC BEACH
COULD SUDDENLY,

AND WITHOUT WARNING,
SWALLOW UP A CHILD.

IT SEEMED TO DEFY
ALL SCIENTIFIC EXPLANATION.

THE THING I FIND SO
INTERESTING ABOUT THIS

IS THAT I HAVE NEVER
HEARD OF SOMETHING

LIKE THIS EVER HAPPENING,

ESPECIALLY
ON A SAND DUNE.

YEAH, THAT'S VERY BIZARRE.

GEOLOGICALLY, THAT
SHOULDN'T HAPPEN.

NEWS REPORTS CALLED IT
A SINKHOLE,

BUT ACCEPTED SCIENCE
SAYS SINKHOLES

DON'T NORMALLY FORM IN SAND.

THEY'RE OFTEN FOUND IN AREAS

WHERE THE EARTH IS LIMESTONE
OR CARBONATE ROCK.

WHEN WATER HAS ERODED
THAT MATERIAL,

THE GROUND SUDDENLY GIVES WAY,

BUT SAND, GRAINY AND MALLEABLE,

SHOULD JUST COLLAPSE
IN ON ITSELF

AS ANY CAVITY STARTS TO FORM.

SO HOW ON EARTH DID A DUNE
SWALLOW UP A 6-YEAR-OLD BOY,

AND IS THERE STILL A RISK
THIS TERRIBLE TRAGEDY

COULD REPEAT ITSELF?

STEFAN AND I AIM TO FIND OUT.

WOW, LOOK AT THIS.

THIS DUNE IS AT LEAST,
LIKE, 80 FEET TALL.

IT'S, LIKE,
SWALLOWING THOSE TREES.

THIS IS AMAZING.

WHEN IS THE RANGER
SUPPOSED TO BE HERE?

THERE SHE COMES RIGHT NOW.

WE'VE ARRANGED TO MEET UP WITH
NATIONAL PARK SERVICE BIOLOGIST,

LAURA BRENNAN,

TO LEARN MORE ABOUT WHAT'S GOING
ON IN THIS LIVING LANDSCAPE.

BUT THESE DUNES ARE MOVING QUITE
A BIT OVER THE PARKING LOT.

I CAN ACTUALLY REMEMBER
WHEN I COULD WALK UP

TO THE BASE OF THOSE
TREES RIGHT THERE.

REALLY?
HOW LONG HAS IT BEEN?

NOT THAT LONG.

AFTER THE INCIDENT, THE NATIONAL
PARK SERVICE CLOSED THE DUNE

UNTIL IT COULD BE DEEMED
SAFE FOR THE SITE'S

NEARLY 2 MILLION
ANNUAL VISITORS,

SO IT REMAINS OFF-LIMITS
TO THIS DAY.

IS IT DANGEROUS, OR ARE
WE FINE GOING UP THERE?

YOU KNOW, SINCE I'M HERE,
I'LL WALK ALONG WITH YOU

AND MAKE SURE
EVERYBODY IS SAFE.

SO, IN THEORY, THERE COULD STILL
BE HOLES THAT SUCK PEOPLE DOWN?

ABSOLUTELY.

LAURA LEADS US UP THE PATH
TOWARDS THE DUNE,

SHOVELS IN HAND.

NOT HIGH-TECH TOOLS,

BUT IF ANYONE GETS
SUCKED UNDER THE SAND,

WE'LL BE ABLE TO
DIG THEM OUT QUICKLY.

RESTRICTED AREA.

YEAH, AND
A RARE PLANT HABITAT.

IT'S GETTING STEEP.

THIS IS THE HARD PART,
HERE.

BUT THE WORK
IS WELL WORTH IT.

OH, WOW.

- WELCOME TO MOUNT BALDY.
- THIS IS HUGE!

I THOUGHT IT WAS
JUST A LITTLE HILL

FROM THE PARKING LOT,

BUT THIS IS...
AND VERY, VERY EXPANSIVE.

THOUGH THE VIEWS
ARE SPECTACULAR,

IT'S FRIGHTENING
TO IMAGINE THE SAND

COULD BE CAPABLE OF CAVING IN
SUDDENLY BENEATH OUR FEET.

LOOKING AROUND, SOMETHING
ELSE CATCHES ME OFF GUARD.

WHAT IS THIS OVER HERE?

YOU KNOW, THAT'S THE
FOUNDATION OF A BUILDING.

IT WASN'T BUILT ON THE DUNE.

IT WAS BUILT ON THE BACKSIDE
OF THE DUNE IN THE FOREST.

- NO KIDDING?
- YEAH.

AND OVER THE YEARS, THE DUNE
HAS GONE UP AND OVER IT?

EXACTLY.

VARIOUS FORCES--
WIND, WEATHER, HUMANS--

ARE COMBINING TO SHIFT SAND
FROM THE TOP AND BEACHSIDE,

EVENTUALLY COVERING UP
STRUCTURES LIKE THIS ONE

ALONG THE PARK'S
15-MILE COASTLINE.

BUT THESE RUINS ARE NOWHERE
NEAR THE LOCATION

WHERE THE BOY
WAS SWALLOWED UP,

SO COULD THE ACCIDENT
STILL BE CONNECTED

TO OTHER BUILDING REMAINS
THAT HAVE BEEN ENGULFED?

WHEN RESCUERS WERE
DIGGING THE BOY OUT,

THEY REPORTED COMING
ACROSS NUMEROUS

SMALL HOLES IN THE SAND,

SOME UP TO 8 INCHES IN DIAMETER,

BUT ALMOST AS SOON AS
THEY WOULD SPOT THEM,

THE OPENINGS WOULD COLLAPSE,

AND SAND WOULD RUSH IN
TO FILL THE VOID.

SINCE THE INCIDENT, RANGERS
HAVE CONTINUED TO FIND HOLES

IN THE SURFACE OF THE DUNE

AND ARE PRETTY CERTAIN
THAT THEY ARE SOMEHOW CONNECTED

TO WHAT HAPPENED HERE.

SO HOW MANY OF THESE HOLES
LIE BENEATH THE DUNE,

AND DO THEY POSE A RISK TO US?

I THINK WE HAVE TO GET EYES
ON A HOLE OR TWO.

NOW REMEMBER,
SOMETIMES, THERE COULD BE A HOLE

THAT YOU DON'T EVEN
SEE ON THE SURFACE.

THE THING THAT'S
SO HARD ABOUT THIS

IS THERE IS NO EVIDENCE,

REALLY, THAT WE CAN SEE
OTHER THAN SAND.

I MEAN, IT'S NOT OBVIOUS
AS TO WHAT CAUSED IT,

AND THAT'S WHAT'S
BAFFLING EVERYBODY.

HAVING STUDIED BIOLOGY
AND MARINE SCIENCES,

I KNOW FIRSTHAND
HOW COASTAL AREAS

CAN TAKE ON A LIFE
OF THEIR OWN.

WHEN SAND BECOMES SATURATED,
WATER CAN DESTABILIZE IT,

TURNING IT INTO
DANGEROUS QUICKSAND

AND PULLING IN WHOEVER
WALKS OVER IT.

BUT THIS DUNE WAS BONE DRY
THE DAY THE BOY FELL INTO IT,

SO THERE MUST BE
SOME OTHER EXPLANATION

FOR THE BIZARRE
OCCURRENCE HERE.

WHOA.
WHOA, WHOA, WHOA, WHOA.

HERE WE GO.

HOLY MOLY.
LOOK AT THAT.

BE CAREFUL.

AS SOON AS WE TRY AND PROBE
THIS HOLE'S OPENING...

I THINK IT MIGHT HAVE ALREADY
COLLAPSED IN ON ITSELF.

SO WE KEEP MOVING IN SEARCH
OF ADDITIONAL HOLES

THAT MIGHT HELP US
ANSWER HOW A CHILD

COULD HAVE BEEN
SWALLOWED UP BY THIS DUNE.

OH, LOOK AT THIS, STEFAN.

WOW, LOOK AT THAT.

OH, YEAH, THAT'S A HOLE
OF SOME SORT.

IT'S RIGHT NEXT
TO A TREE TRUNK,

WHICH SEEMS TO BE
SPROUTING OUT OF THE DUNE.

IT LOOKS LIKE THIS TREE STUMP
HAS BURNT IN THE PAST,

EITHER THAT, OR HAD
SOME BLACK FUNGUS ON IT.

THE HOLE APPEARS TO RUN
DOWN ALONGSIDE THE TRUNK.

CAN YOU TELL
HOW DEEP IT GOES?

LET ME PROBE IT.

UH...

ABOUT A FOOT.

OH, THAT'S DEEP.

WON'T BE A HOLE
IN A SECOND, STEFAN.

BEFORE WE GO ANY FURTHER,

I WOULD LOVE TO SEE WHAT'S
AT THE BOTTOM OF THIS.

THE SIZE AND SHAPE
OF THESE HOLES

SEEM CONSISTENT
WITH ANIMAL BURROWING.

I WANTED TO GET A LOOK
INSIDE OF ONE TO SEE

IF THERE ARE ANY SIGNS
OF ANIMAL ACTIVITY.

GIVEN THE DELICATE NATURE
OF THESE OPENINGS

AND THEIR TENDENCY
TO COLLAPSE IN ON THEMSELVES,

I DON'T WANT TO TRY DIGGING IN.

CAN WE GET
THAT BOREHOLE CAMERA,

GET IT IN THERE AND CHECK
IT OUT, LIGHT IT UP?

YEAH, WE CAN THROW IT IN THERE,
SEE HOW FAR IT GOES.

I'LL GRAB IT.

OUR BOREHOLE CAMERA
IS SPECIFICALLY USED TO VIEW

SMALL AREAS UNDERGROUND
INACCESSIBLE TO THE NAKED EYE.

IT WILL ALLOW US TO SEE
INSIDE THE HOLE

WITHOUT DISTURBING THE
SURROUNDING SAND TOO MUCH.

ALL RIGHT.
I HAVE THE CAMERA.

THIS THING IS SUPER COOL.

BASICALLY, THIS BOREHOLE CAMERA
HAS A LITTLE LIGHT AT THE END

AS WELL AS A CAMERA,
AND IT'S 25 FEET LONG,

SO WE CAN SNAKE IT
INTO THESE SPOTS,

AND ONCE FULLY EXTENDED,
IT HAS AN ARTICULATING HEAD.

AND THE END OF IT
CAN MOVE AROUND.

WILL OUR CAMERA REVEAL
THE PRESENCE OF ANIMAL BURROWS

OR GIVE US OTHER CLUES

AS TO WHAT'S CAUSING
THESE BIZARRE HOLES TO FORM?

IT'S GOING DOWN.

2 INCHES,
3 INCHES,

4 INCHES.

AH, CRUD.

UNDERGROUND TECH EXPERT
STEFAN BURNS AND I

ARE IN INDIANA
ATTEMPTING TO EXPLAIN

HOW A YOUNG CHILD WAS SWALLOWED
UP INTO A MASSIVE SAND DUNE.

WELL,
LOOK AT THIS, STEFAN.

OH, YEAH.
THAT'S A HOLE OF SOME SORT.

WE ARE USING OUR SPECIALIZED
BOREHOLE CAMERA

ON A SMALL OPENING TO FIND OUT

IF BURROWING ANIMALS
ARE HOLLOWING OUT THE DUNE

BENEATH OUR FEET,

MAKING IT AN UNSTABLE DEATH TRAP
FOR ANYONE WALKING ABOVE.

IT'S GOING DOWN.

2 INCHES,
3 INCHES,

4 INCHES.

AH, CRUD.
- OH, IT JUST FELL IN.

OH, CRUD.

IT KIND OF COLLAPSED
IN ON ITSELF.

YEAH.

I MEAN, THAT'S THE BIGGEST
HOLE WE'VE FOUND,

BUT THAT'S DEFINITELY
NOT SOMETHING

THAT COULD SWALLOW
A CHILD UP.

IT SEEMS THE BOREHOLE CAMERA
WON'T GIVE US THE LOOK WE NEED

TO FIGURE OUT WHAT'S CAUSING
THESE OMINOUS HOLES

TO APPEAR BENEATH
THE SURFACE OF MOUNT BALDY.

WE HAVE TO FIND IT
UNDERGROUND.

YEAH, I THINK IT'S TIME
TO USE THE GPR

AND TO SCAN
THIS ENTIRE AREA,

JUST BUILD A 3-D MAP OF ALL
THE STRUCTURES UNDERGROUND.

GROUND-PENETRATING RADAR,
CALLED GPR FOR SHORT,

WORKS BY FIRING RADIO WAVES
INTO THE GROUND

AND SHOULD REVEAL ANY CAVITIES
BURIED BENEATH THE SURFACE.

WHILE I KEEP LOOKING FOR HOLES,

STEFAN GETS TO WORK
SETTING UP A GRID

SO THAT WE CAN DETERMINE
IF ANIMAL BURROWS

WERE INDEED
WHAT THE CHILD FELL INTO.

SO HE BEGINS THE SCAN,
WHICH IS HARD WORK.

PUSHING IN SAND
IS THE WORST.

BUT WILL IT PAY OFF?

LOOK AT THIS.

THESE ARE HUGE,

TWO PERFECT FEATURES,
ONE AT 13 FEET,

AND ONE AT 8 FEET.

I'LL KEEP SCANNING TO SEE
IF THERE'S MORE OF THEM.

AS STEFAN'S SCAN CONTINUES,

HE BEGINS TO SEE MORE
AND MORE HOLES

RIGHT UNDERNEATH HIS FEET,

WHICH CAN BE DANGEROUS
IF HE TAKES A WRONG STEP.

YES.

THAT SURVEY WAS BRUTAL,
60 BY 100 FEET,

BUT I SAW SO MUCH IN THERE.

STEFAN'S SCAN HAS
REVEALED SOMETHING TERRIFYING.

THERE APPEAR TO BE
NUMEROUS VOIDS

VARYING IN SHAPES AND SIZES

AND EVEN POSITIONED
AT DIFFERENT ANGLES.

THIS UNDERGROUND LABYRINTH
APPEARS TO BE STRUCTURED

LIKE SWISS CHEESE,

MAKING IT SEEM LESS LIKELY THAT
ANIMAL BURROWING IS INVOLVED.

THESE HOLES DO NOT MAINTAIN
A CONSISTENT DIAMETER

THAT WE WOULD NORMALLY SEE
WITH ANIMAL ACTIVITY.

SO IF ANIMAL BURROWS ARE NOT
TO BLAME FOR THE BOY'S ACCIDENT,

THEN WHAT IS?

IF WE CAN IDENTIFY WHAT CAUSED
THESE SUBTERRANEAN POCKETS

TO FORM,

WE MAY BE ABLE TO PREVENT
THIS FROM HAPPENING AGAIN

AND ENSURE THE SAFETY
OF THE 2 MILLION PEOPLE

THAT VISIT EACH YEAR.

WE ARRANGE TO MEET UP
WITH KEVIN RUSSELL...

KEVIN.
- HEY, GOOD MORNING, ROB.

...A CARTOGRAPHER FROM
THE INDIANA GEOLOGICAL SURVEY.

HE HAS SOME OLD MAPS
AND AERIAL PHOTOS OF THE AREA

THAT MIGHT SHED SOME LIGHT
ON WHAT'S CAUSING THIS DUNE

TO TAKE ON
A SWISS-CHEESE-LIKE STRUCTURE.

HERE IS AERIAL IMAGERY
FROM JUNE 1, 1939,

OF THE INDIANA SHORELINE,

AND THIS IS FROM 1958,
TAKEN SEPTEMBER 13th.

OKAY, LET'S COMPARE THESE TWO
TO EACH OTHER REAL QUICK.

LET'S SEE.

THOUGH MORE RECENT AERIAL
SURVEYS HAVE BEEN DONE,

THESE MID-CENTURY MAPS
ALLOW US TO SEE

WHAT THE DUNE HAS COVERED UP
IN THE PREVIOUS CENTURY,

GIVING US MORE CLUES
AS TO WHAT MIGHT BE

LYING HOLLOW BENEATH IT.

WE ALREADY KNOW THAT THE DUNE
HAS BEEN MOVING INLAND

FOR THE PAST FEW DECADES,

BUT BY LOOKING AT THESE PHOTOS,

WE KNOW SEE HOW MUCH AREA

IT ACTUALLY ENGULFED
IN ONLY 20 YEARS.

THESE MAPS ARE GREAT
BECAUSE IT ALLOWS US

TO SEE WHAT COULD HAVE BEEN
THERE BEFORE THE SAND WAS,

WHICH MIGHT ALLOW US
TO FIGURE OUT

HOW AN AIR GAP
WAS FORMED...

- YEAH.
- ...THAT HE FELL INTO.

IF WE ARE ABLE TO PINPOINT
WHAT EXACTLY ON THIS LAND

THE DUNE HAS COVERED SINCE 1939,

WE MIGHT BE ABLE TO EXPLAIN
WHAT THE BOY FELL INTO.

THIS DUNE IS MOVING
AT A FAST RATE,

OVERTAKING EVERYTHING
IN ITS PATH.

YEAH.

AND ACCORDING TO THESE MAPS,

THAT EVERYTHING INCLUDES
MAN-MADE STRUCTURES.

THIS IS, LIKE,
A LITTLE DRIVEWAY,

AND THIS LITTLE
SQUARE AT THE END,

I WOULD ASSUME
THAT'S A HOUSE.

THERE'S ANOTHER ONE THERE.

CAN YOU SEE ANY
STRUCTURES IN THERE?

WELL, THERE'S A STRUCTURE
RIGHT THERE.

MM-HMM.

IT'S COVERED UP, NOW,
IN THIS ONE COMPLETELY.

COULD THESE STRUCTURES
BE WHAT STEFAN SAW ON THE GPR?

IF SO, MAYBE THAT HELPS
EXPLAIN WHAT HAPPENED HERE.

DO YOU THINK THAT COULD BE
WHERE THE KID FELL INTO

WAS ONE OF THESE OLD BUILDINGS?

IF A HOUSE WAS TO GET BURIED
BY A SAND DUNE,

IT'S JUST GONNA BE
A BIG POCKET OF AIR INSIDE,

AND EVENTUALLY, IF THERE'S
ENOUGH WEIGHT ON TOP OF IT,

IT WOULD COLLAPSE.

DO YOU THINK THE THEORY
HOLDS ANY WATER?

I THINK
IT'S A POSSIBILITY.

COULD THIS DUNE BE RIDDLED
WITH AN UNDERGROUND TOWN

OF OLD AND FORGOTTEN BUILDINGS

THAT COULD POTENTIALLY
BE A DEATH TRAP

FOR ANY FUTURE VISITORS?

THIS IS MAKING ME WANT TO GET
A 3-D MAP OF THE AREA

AND MAYBE TRY TO REFERENCE
IT BACK TO THESE OLD MAPS.

SO WE COULD SHOW
HISTORICALLY

WHERE THESE BUILDINGS WERE...
- YEP.

...WHERE THE DUNE IS AND WHERE
THE BUILDINGS ARE NOW,

AND WHERE THE GPR
ANOMALIES WERE,

AND IF THEY ALL CORRELATE
TOGETHER, BINGO.

WHILE STEFAN AND KEVIN
CONTINUE TO STUDY THE MAPS,

I'M GOING TO FLY MY DRONE
HIGH ABOVE THE DUNE

AND CAPTURE THE STILLS WE NEED,

CREATING A 3-D MAP
TO HELP US FIGURE OUT

WHAT UNSTABLE UNDERGROUND WORLD

LIES BENEATH THE DUNE.

BUT HERE'S THE KICKER--
I CAN'T LAUNCH IT FROM LAND.

THE LAW REQUIRES ME TO BE
AT LEAST 300 FEET OFFSHORE

TO PROTECT THE RESOURCES
OF THE NATIONAL PARKS,

SO I'M HEADING OUT ON
LAKE MICHIGAN TO MAKE THE MAP.

PHOTOGRAMMETRY WEAVES TOGETHER
MULTIPLE 2-D IMAGES

TO CREATE
A THREE-DIMENSIONAL MODEL,

IN THIS CASE, OF THE DUNE.

WE'LL BE ABLE TO LAYER
THIS UP-TO-DATE IMAGE

ON TOP OF THE HISTORICAL AERIALS

AND THE GPR RESULTS
TO EXPLORE OUR THEORY

THAT A LOST UNDERGROUND TOWN

MIGHT BE COLLAPSING
BENEATH THE SAND,

CREATING THE DUNE'S
BIZARRE HOLES.

HERE WE GO.

THE DRONE WILL BE RUNNING
AN AUTOMATED FLIGHT PATH,

TAKING IMAGES FROM
SPECIFIC POINTS

I'VE PLOTTED ON A GPS GRID.

OKAY, SO IT'S FLYING UP
TO 400 FEET RIGHT NOW,

AND IT'S GONNA TAKE
AN IMAGE EVERY 20 FEET

UP AND DOWN ACROSS THE DUNE.

COOL.

LAST ONE.

YEP, THAT ONE WAS GOOD.

WITH THE PHOTOGRAMMETRY
A SUCCESS,

I'LL MEET BACK UP
WITH STEFAN AND KEVIN

TO SHOW THEM THE RESULTS.

HEY, GUYS.
- WELCOME BACK.

- SO SHOW US WHAT YOU'VE GOT.
- YOU GUYS ARE GONNA LIKE THIS.

WE'VE USED
SPECIALIZED SOFTWARE

TO KNIT THE 2-D IMAGES TOGETHER

TO CREATE A SINGULAR,
3-D IMAGE OF MOUNT BALDY.

SO YOU CAN ROTATE IT AROUND,

BUT YOU CAN SEE THE SHAPE

OF THE DUNE REALLY
CLEARLY FROM HERE,

AND WHAT
I FIND SO INTERESTING

IS THAT FROM THE OLD
TOPOGRAPHIC MAPS,

MOUNT BALDY WAS HERE.

YES.

THE PHOTOGRAMMETRY HAS
GIVEN US

THE MOST CURRENT MAP
OF MOUNT BALDY.

WE WILL NOW BE ABLE
TO CROSS-REFERENCE THIS IMAGE

OVER THE 1958 MAP IN ORDER
TO VISUALIZE THE DISTANCE

THE DUNE HAS TRAVELED SINCE
FROM AN AERIAL POINT OF VIEW.

IT HAS GIVEN US THE ABILITY
TO USE THE PARKING LOT

AS A REFERENCE POINT
TO SEE EXACTLY WHAT THE DUNE

HAS CONSUMED
IN THE PAST 50 YEARS.

WHILE TAKING A CLOSER LOOK,

WE NOTICE THAT THERE ARE MORE
THAN JUST BUILDINGS AND ROADWAYS

THAT THE DUNE HAS COVERED UP.

LOOK HOW IT'S OVERTAKING
THIS FOREST.

WHEN I RAN THE GPR OVER THE
AREA, I GOT TONS OF ANOMALIES,

MORE THAN CAN BE EXPLAINED JUST
BY THE STRUCTURES IN THE AREA.

WITH THE ADDITION
OF STEFAN'S GPR SCAN,

WE'LL BE ABLE TO CREATE
A MORE THOROUGH IMAGE

OF ANY HOLES
THAT LIE UNDERNEATH.

I MEAN, IT'S COMPLETELY
ENGULFING THIS FOREST,

SO WHAT I STARTED THINKING ABOUT
WHEN WE STARTED LOOKING AT THIS

IS THAT WE WERE HONING IN
ON THESE STRUCTURES

THAT THE DUNE
HAS ENGULFED, RIGHT?

YEAH.

BUT EVERY SINGLE ONE
OF THESE TREES

IS TECHNICALLY A STRUCTURE.

THERE ARE SO MANY TREES
AND SO FEW STRUCTURES

THAT THE PROBABILITY
OF THE HOLE LINING UP

WITH THE POSITION OF A TREE

SEEMS FAR MORE LIKELY THAN
ALIGNING WITH AN OLD BUILDING.

SO WHERE EXACTLY DID THE KID
FALL INTO THE HOLE?

IN THIS GENERAL AREA
RIGHT HERE.

OKAY.

ARE THERE ANY STRUCTURES
THERE OR TREES?

NO, LOOK AT THAT.

SEE ALL THE TREES
LYING UNDERNEATH

THE SURFACE OF THE DUNE?

- WHOA.
- HERE, CHECK THAT OUT.

CHECK THAT OUT.
- LOOK AT THAT.

COULD THESE TREES
HAVE CREATED THE HOLE

THAT BURIED THE BOY ALIVE?

HONESTLY, THE WHOLE THING
SEEMS VERY UNUSUAL TO ME.

STEFAN AND I
ARE ON A MISSION

TO UNCOVER HIDDEN SECRETS
BENEATH MOUNT BALDY

THAT COULD EXPLAIN
WHAT CAUSED A 6-YEAR-OLD CHILD

TO GET SUCKED INTO
AN UNEXPLAINED HOLE.

WE HAVE JUST COMBINED OUR GPR
AND PHOTOGRAMMETRY MAPS

TO GET A COMPREHENSIVE LOOK
AT THE DUNE'S MIGRATION PATH,

AND ONE THING IS
BECOMING MORE EVIDENT.

LOOK AT THAT.
SEE ALL THE TREES

LYING UNDERNEATH
THE SURFACE OF THE DUNE?

- WHOA.
- HERE, CHECK THAT OUT.

CHECK THAT OUT.
- LOOK AT THAT.

THE DUNE HAS COVERED UP
PARTS OF THE FOREST

WHERE TREES SEEM TO BE
SCATTERED UNDERNEATH,

BUT IF THE HOLE WAS,
AT ONE POINT, A TREE,

HOW COULD IT HAVE CREATED
A VOID UNDER THE DUNE

FOR THE BOY TO FALL INTO?

I MEAN, THERE HAS TO BE
SOME PROCESS AT PLAY

THAT'S RESPONSIBLE FOR
DISINTEGRATING THESE TREES,

MAYBE THROUGH
SOME DECOMPOSITION,

OR THERE'S SOMETHING
THE SAND...

THE WAY I SEE IT,

IT EITHER IS SOMETHING
IN THE SAND THAT'S CAUSING THIS,

OR IT'S SOMETHING
WITHIN THE TREE ITSELF.

HOW DO YOU THINK THESE TREES
INTERACT WITH THE DUNE

ONCE THEY'RE BURIED?

THE WHOLE THING IS
SOMEWHAT PERPLEXING TO ME.

SAND DUNES WILL COMMONLY
ENVELOP TREES

AND OTHER VEGETATION.

IN EXTREME CASES,
SEISMIC ACTIVITY OR EXPOSURE

TO SEA LEVEL CHANGES

WILL COMPLETELY ENGULF
GROVES OF TREES

IN SAND, MUD OR WATER.

IT'S A PROCESS THAT CAN RESULT
IN WHAT'S CALLED A GHOST FOREST.

AREAS SUCH AS THE NESKOWIN
GHOST FOREST IN OREGON

WERE COVERED IN SEDIMENT,

PRESERVING THE TREE
STUMPS UNDERNEATH.

ANOTHER FOREST IN WYOMING
BECAME ENCASED IN ALGAE,

PROTECTING IT FROM NATURAL
ELEMENTS THAT CAUSE DECAY.

PETRIFICATION OCCURS WHEN
TREES ARE SHIELDED

FROM DECOMPOSITION LIKE THIS.

SOLID MINERALS THEN REPLACE
THE ORGANIC MATERIAL,

A PROCESS THAT WOULD NOT
CREATE THE EMPTY CAVITIES

WE'VE SEEN ON MOUNT BALDY.

THESE TREES WERE POTENTIALLY
RESPONSIBLE FOR THE INCIDENT,

THEN THE TREES HARDENING
AND PETRIFYING

WOULD BE THE EXACT OPPOSITE

OF WHAT WOULD ACTUALLY
NEED TO HAPPEN.

THESE TREES WOULD NEED TO HOLLOW
OUT SOMEHOW AND LEAVE A SPACE.

BUT EVEN IF THAT WERE TO HAPPEN,

WOULDN'T THE SURROUNDING SAND

JUST COLLAPSE BACK
INTO THE TREE,

FILLING IN ANY HOLE IMMEDIATELY?

HONESTLY, I'VE NEVER
SEEN THIS BEFORE,

AND I THINK WE'RE GOING
TO NEED TO TAKE SOME SAMPLES,

GO SEE A TREE EXPERT.

RUNNING WITH OUR HYPOTHESIS,
THE DECOMPOSING TREES

SOMEHOW LEFT BEHIND AIR GAPS
BENEATH THE SAND.

I HEAD BACK OUT TO THE DUNE
TO COLLECT SOME TREE SAMPLES.

OH, LOOK AT THAT.

THERE'S SOME SOIL
RIGHT ON THE EDGE OF THAT TREE.

ANY DIFFERENT BIT OF SOIL
IS IMPORTANT,

SO THIS STUFF AROUND THIS TREE,
THAT'S HARDER, MORE CONDENSED.

IT FEELS LIKE IT'S BASICALLY
THE DECOMPOSED TREE RIGHT THERE.

AND UPON FURTHER INSPECTION, ONE
OF THESE SAMPLES CATCHES MY EYE.

LOOK AT THE FUNGUS
GROWING ON THIS ONE.

I'LL TAKE THIS WITH ME.

WOULD THIS FUNGUS
HAVE ANYTHING TO DO

WITH THE TREE'S DECOMPOSITION?

THERE'S ONLY ONE WAY
TO FIND OUT,

SO WE'RE HEADING TO NEARBY
INDIANA UNIVERSITY

TO MEET WITH PETE AVIS...

- HEY, HOW ARE YOU DOING?
- PETE.

...A BIOLOGIST WHO ALSO
SPECIALIZES IN MYCOLOGY,

THE STUDY OF FUNGI.

WHAT HAPPENS WHEN
A DUNE ENGULFS A TREE?

SO THE TREE PROBABLY DIES,

AND THE SAND COMING
ON TOP OF THE TREE

IS GONNA
CUT OFF THE LIGHT,

AND THAT'S GONNA STOP
THE TREE

FROM DOING PHOTOSYNTHESIS.

AND THEN PRESUMABLY,

DECOMPOSITION CAN
START TO RAMP UP.

THIS CONFIRMS OUR SUSPICION

THAT THERE IS NO PETRIFICATION
OF THE TREES OCCURRING,

BUT IT DOESN'T
ANSWER THE QUESTION

OF WHY THE SAND WOULDN'T JUST
SETTLE AROUND THE DECAYING TREES

AND FILL IN ANY POTENTIAL HOLES.

I'VE OFFERED UP MY SAMPLES
FOR PETE TO TAKE A CLOSER LOOK.

THIS, WHICH I PULLED OFF
THE SIDE OF ONE OF THE STUMPS,

WAS JUST BARELY EXPOSED.

I THOUGHT IT WAS
REALLY INTERESTING

BECAUSE IT HAD LITTLE
BITS OF FUNGUS.

YEAH, YEAH, YEAH.

SO I'M CURIOUS WHAT YOU
CAN TELL FROM SOME OF THIS.

USUALLY, WHEN THEY'RE
ASSOCIATED THIS CLOSE TO WOOD,

THEY'RE INVOLVED IN
THE DECOMPOSITION OF IT,

AND THERE'S A LOT OF FUNGI

THAT DECOMPOSE THE CENTER
OF THE TREE

AND BASICALLY STARTS
ON THE INSIDE OF THAT TRUNK,

WORKS ITS WAY OUT.

IT DOESN'T TOUCH
THAT OUTER RING.

AND SO YOU'VE GOT A CYLINDER
AROUND A HOLLOW MIDDLE.

PETE TELLS US THAT FUNGI CAN
ENTER THE TREE THROUGH THE BARK

AND DECAY THE INTERIOR
PORTIONS CALLED HEARTWOOD.

THIS DECAYING PROCESS
CAN TAKE YEARS,

WITH SOME FUNGI KNOWN
TO DECOMPOSE WOOD

AT THE RATE OF 2
TO 3 INCHES PER YEAR,

AND AFTER BEING
BURIED INSIDE A DUNE,

IT COULD TAKE A FEW
DECADES FOR A TREE

TO BE COMPLETELY EATEN
FROM THE INSIDE

LEAVING ONLY THE SHELL.

BASED ON THE OLD
AERIAL MAPS WE'VE SEEN,

THIS TIME FRAME ALIGNS WITH
THE RATE AT WHICH MOUNT BALDY

HAS BEEN ENGULFING
THE SURROUNDING FOREST.

COULD THIS UNUSUAL
DECOMPOSITION PROCESS

BE WHAT'S LEAVING BEHIND
THE HOLES ON MOUNT BALDY

THAT CAUSED THE TRAGIC EVENT?

WE NEED TO FIGURE OUT
IF THE FUNGUS WE FOUND ON SITE

IS THE KIND THAT DECAYS WOOD
FROM THE CENTER OUTWARD,

SO PETE DECIDES TO TAKE
A CLOSER LOOK AT OUR SAMPLE

UNDER A MICROSCOPE.

YEAH, THIS IS DEFINITELY
ONE OF THE KINDS OF FUNGI

THAT WOULD BE INVOLVED
IN DECOMPOSING

THE TREES FROM THE INSIDE OUT.

OH, WOW, LOOK AT THAT.

IT'S AN INCREDIBLE REVELATION,

SUGGESTING THAT THIS BIZARRE
VARIETY OF FUNGUS

IS RESPONSIBLE FOR HOLLOWING OUT
TREES BENEATH THE SAND DUNE,

LEAVING BEHIND
DANGEROUS HOLLOW TUBES

SUPPORTED BY THE REMNANTS
OF TREE BARK.

IT IS AMAZING TO THINK THAT
SOMETHING AT THE MICROBIAL LEVEL

COULD BE THE CAUSE OF SUCH
A HORRIFIC ACCIDENT,

AND IT'S A TRULY UNEXPECTED
ENDPOINT TO OUR INVESTIGATION.

FOR NOW, THE DUNE
REMAINS OFF-LIMITS

TO THE GENERAL PUBLIC,

BUT WITH THIS INFORMATION
COMING TO LIGHT,

IT WILL ONLY BETTER INFORM
THE U.S. PARK SERVICE

ON HOW TO BEST MANAGE THE DUNE,

PREVENTING TRAGIC ACCIDENTS FROM
HAPPENING AGAIN IN THE FUTURE

AND POSSIBLY SAVING
THE LIVES OF OTHER CHILDREN

THAT WISH TO MAKE THE SAME HIKE
THAT THE YOUNG BOY MADE.

OKAY, ON THE ROAD AGAIN.
I'M STOKED.

AND NOW WE'RE HEADING TO A
MYSTERIOUS SUBTERRANEAN LOCATION

ON THE EAST COAST
THAT'S PUZZLED SCIENTISTS

SINCE ITS DISCOVERY IN 1894.

IN COUDERSPORT, PENNSYLVANIA,

NESTLED IN
THE APPALACHIAN MOUNTAINS,

IS A NATURAL ODDITY
THAT DEFIES THE LAWS OF NATURE,

A NEARLY 40-FOOT MINE
UNLIKE ALMOST ANY OTHER ON EARTH

HAS BEEN PRODUCING SPARKLING
CLEAR ICE IN THE SUMMER

THAT MELTS IN THE WINTER.

FIRST DISCOVERED
IN THE LATE 19th CENTURY

BY A PROSPECTOR
SEARCHING FOR SILVER,

THE MINE WAS USED BY LOCALS

TO REFRIGERATE MEAT
IN THE SUMMER MONTHS.

AS WORD SPREAD, VISITORS FLOCKED
TO MARVEL AT THE ICY CURIOSITY,

BUT NO ONE COULD EXPLAIN
WHAT STRANGE FEAT OF NATURE

COULD CAUSE SUCH
AN ODD PHENOMENON.

SO STEFAN AND I ARE GOING TO
CHECK THIS OUT FOR OURSELVES.

HEY, ROB, SO YOU WANT
TO TURN LEFT UP HERE.

YEAH, GOOD IDEA.

WE'RE BRINGING ALONG
A CADRE OF EQUIPMENT

NEVER BEFORE USED HERE
TO HOPEFULLY,

FINALLY GET AN ANSWER

TO WHAT'S BEEN BAFFLING PEOPLE
FOR MORE THAN 100 YEARS.

HEY, GARY!
- GOOD MORNING.

ROB NELSON, HOW ARE YOU DOING?

- FINE, SIR.
- HEY, GOOD TO MEET YOU.

GOOD MORNING. WELCOME
TO COUDERSPORT ICE MART.

WE'RE MEETING UP
WITH GARY BUCHSEN,

WHO OWNS THE PROPERTY THAT
HOUSES THE COUDERSPORT ICE MINE.

YEAH, I WANT TO SEE THIS THING.

OKAY, GREAT.
YOU'RE GONNA GO THROUGH HERE.

WOW.
IT'S COLD.

THE DOORWAY IS LIKE A PORTAL.

OUTSIDE IS SWELTERING
SUMMER HEAT,

INSIDE, A BITING, FRIGID AIR.

HOLY MOLY, LOOK AT THAT.

THAT'S FREEZING.

IT IS NOT UNUSUAL

TO HAVE 50 DEGREES'
DIFFERENCE IN TEMPERATURE

WHEN WE'RE
ONLY 15 FEET AWAY.

THE CHILL EMANATES FROM
THE CENTERPIECE WITHIN THE MINE,

A 14-BY-34-FOOT VERTICAL
SHAFT CASCADING WITH ICICLES.

THIS IS REALLY UNUSUAL.

OBVIOUSLY, IT'S A VERY
UNUSUAL, VERY UNIQUE...

IT'S ONE
OF THE COLDEST SPOTS

IN THE EASTERN PART
OF UNITED STATES

ALL THE WAY FROM FLORIDA
CLEAN UP INTO MAINE.

WE HAVE A LOT OF PEOPLE
FROM DIFFERENT COMPANIES

AND FROM DIFFERENT COLLEGES.

WE'VE HAD GEOLOGISTS COME
OUT HERE, AND THEY JUST SAY,

"YOU KNOW, I DON'T KNOW
WHAT'S HAPPENING HERE."

SOME BELIEVE THAT THE MINE
IS PART OF A DYNAMIC CAVE SYSTEM

WITH MULTIPLE ENTRANCES
WITH COLD AIR

FLOWING INTO THE MINE
FROM VARIOUS PASSAGEWAYS,

BUT THE EXISTENCE OF SUCH
ENTRANCES HAS NEVER BEEN PROVEN,

AND EVEN IF THEY WERE FOUND,

WHERE WOULD ALL THE SUBFREEZING
AIR BE COMING FROM?

DUE TO COLLAPSING ROCK
WITHIN THE CAVERN,

ACCESS HAS BEEN
PROHIBITED FOR YEARS,

BUT THE PROSPECT OF UNCOVERING
THE SOUGHT-AFTER EXPLANATION

IS TOO TEMPTING,

AND WE'RE GOING IN
AT OUR OWN RISK.

BUT, OBVIOUSLY, WHEN YOU
GO DOWN IN THERE,

IF AN ICICLE OF WHATEVER
WEIGHT WOULD FALL OFF

AND HIT YOU,
YOU'RE AT YOU'RE OWN RISK.

WELL,
IF IT FALLS ON ANYBODY,

IT'S PROBABLY GOING
TO FALL ON STEFAN.

OKAY.

THAT'S JUST USUALLY
HOW IT WORKS.

UNLOCKING THIS MYSTERY REQUIRES
BUSTING OUT OUR TOP TECH...

IT LOOKS GOOD.
YOU GUYS ARE...

YEP. GOOD DRIVING.

...AS WELL AS SOME
SCIENTIFIC INGENUITY.

THIS IS COOL.

WE'RE AT THE LEGENDARY

COUDERSPORT ICE MINE
IN PENNSYLVANIA,

WHERE ICE MYSTERIOUSLY
FORMS IN THE SUMMER

AND MELTS IN THE WINTER,

AND STEFAN AND I ARE ON
A MISSION TO FIND OUT WHY.

OKAY.

AND I'M THINKING THAT
WE'RE GONNA WANT

TO COME RIGHT DOWN
THROUGH HERE.

WE'RE ENTERING WITH
EXTREME CAUTION.

I'M ACTUALLY GONNA GET IN
FROM THIS SIDE THERE.

I THINK
THAT'LL BE EASIER.

THE ROCK STRATA HOLDING UP THIS
MINE RESEMBLES A GAME OF JENGA.

IF A LOAD-BEARING PIECE GETS
PUSHED OR KICKED HARD ENOUGH,

IT'S POSSIBLE THE WHOLE
SHELF COULD TOPPLE.

GOT IT?
OKAY, I'M COMING DOWN, TOO.

ALL RIGHT.

IT'S ALSO VERY
SLIPPERY DOWN HERE.

ALL RIGHT.

WOW, LOOK AT THIS.

OH, MY GOODNESS.

WOW, THIS IS INCREDIBLE.

THIS IS REALLY COOL.

- YEAH.
- AND IT'S REALLY COLD.

IT IS FREEZING.

I'M TRYING TO OPEN THIS POCKET
UP FOR MY HANDS,

AND MY FINGERS
ARE GOING NUMB.

I HAVE A COUPLE CAPS
FOR YOU GUYS,

ONE SIZE FITS ALL.

OH, THIS IS FANTASTIC.

OH, THIS IS
VERY SOFT, TOO.

BUT IT JUST MIGHT KEEP
YOUR EARS A LITTLE BIT WARMER.

HOW DO I LOOK,
PRETTY GOOD, RIGHT?

ALL RIGHT.
WE'RE DOING THIS.

WE'RE DOING THIS.

WE ONLY JUST DESCENDED
INTO THE CAVE,

AND THE PECULIARITIES
ARE GLARING.

NOT ONLY DOES THE ICE CAVE
DEFY SUMMER, BUT GRAVITY, TOO.

THE ICICLES GROW UP, NOT DOWN.

LOOK AT THE ICE ITSELF.

SEE HOW CLEAR IT IS?
- UH-HUH.

THIS ISN'T WATER
THAT'S, LIKE, LET'S SAY,

RISING FROM THE SURFACE
THAT HAS MINERALS IN IT.

IT'S VERY LIKELY

THAT THIS IS BEING
DRAWN OUT OF THE AIR.

NOW, LOOK AT THAT.

IT'S PRECIPITATING
OUT OF THE AIR?

YEAH.

THE RISING ICE IS A CLUE.

THIS PRECIPITATION OCCURS WHEN
MOIST AIR COOLS DRASTICALLY.

WHEN THE HUMID AIR FROM ABOVE
IS PUSHED DOWNWARD

INTO THE FRIGID CAVERN,

WATER PARTICLES
BEGIN TO SOLIDIFY,

EVENTUALLY TURNING INTO ICE,

BUT WHERE IS ALL THIS
COLD AIR COMING FROM?

YEAR-LONG ICE CAVES HAVE BEEN
DOCUMENTED IN CHINA,

AUSTRIA AND SLOVAKIA,

BUT ALL THESE HAVE DIFFERENT
CONTRIBUTING FACTORS--

AIRFLOW FROM A NETWORK OF CAVES,

THE PRESENCE OF WATER
OR COLD TRAPS.

NONE OF THESE FACTORS HAVE
BEEN CONFIRMED AT THIS SITE,

AND SO FIRST,
WE'RE GOING IN SEARCH

OF THE MOST LOGICAL SOURCE--

SOME SUBTERRANEAN CAVE SYSTEM

THAT'S RELEASING
COLD AIR INTO THE MINE.

WE SHOULD DO SOME
AIRFLOW TESTS TO GO AHEAD

AND, YOU KNOW, FIND OUT

IF THERE IS ANY DRAFTS
IN HERE.

TO TEST OUT IF AIR IS BEING
PUSHED INTO THE MINE

BY SUCH A SYSTEM,
WE'LL USE AN AIRFLOW METER.

IT WILL MEASURE THE SPEED
OF ANY AIR CURRENT

THAT IS FLOWING FREELY
IN OR OUT OF THE MINE,

SO WILL IT EXPOSE
ANY HIDDEN PASSAGEWAYS

DEEP WITHIN THESE WALLS?

TRY THAT GUY
RIGHT BEHIND YOU,

BUT STICK IT IN
AS FAR AS YOU CAN.

GOSH, THERE IS A DEEP HOLE
RIGHT THERE.

THIS IS
A REALLY SMALL SPACE.

I CAN SEE WHY THEY DON'T
WANT ANYBODY DOWN HERE.

IT'S KIND OF SKETCH.

YEAH.

THE FOUNDATIONS OF THIS CAVE
ARE A BIT PRECARIOUS.

IF ANY OF THIS ICE OR ROCK
WERE TO DISLODGE,

IT'S POSSIBLE THE ENTIRE THING
COULD COLLAPSE IN ON ITSELF.

WATCH YOUR HEAD, THERE.

OH, GOD,
LOOK HOW LOOSE THAT IS.

IT'S BRITTLE.

- THIS IS ALL REALLY FRACTURED.
- UH-HUH.

I MEAN, THERE ARE TONS OF, LIKE,
LITTLE FISSURES AND GAPS.

AND IT'S CLEAR THERE AREN'T
GOING TO BE ANY SHORTCUTS

IN THIS INVESTIGATION.

THIS CAVE IS RIDDLED
WITH THOUSANDS OF TINY HOLES.

THE AIRFLOW COULD BE COMING
FROM ANY ONE OF THEM.

I THINK
WE NEED SOME WAY TO,

LIKE, TRACK THE AIR
IF THAT MAKES SENSE.

WHAT MIGHT HELP IS SOMETHING
THAT WILL GIVE US

A VISUAL AID OF THIS SPACE.

I BROUGHT SOMETHING VERY SPECIAL
JUST FOR THIS MOMENT.

SO CHECK IT OUT.

I'LL RIG UP WHATEVER IT TAKES
TO GET THE JOB DONE,

LIKE ATTACHING A WALKING
STICK TO A SMOKE MACHINE.

WE'VE GOT SMOKE.

OKAY, I'M GOING DOWN.

ALL RIGHT.
BEST OF LUCK.

BY USING SMOKE, WE'LL BE ABLE
TO VISUALLY DETECT

EVEN THE SLIGHTEST
AIRFLOW IN THE MINE.

DO YOU SEE IT GOING INTO
ANY FISSURES OR FRACTURES?

I DON'T SEE IT GOING
INTO FRACTURES.

SO WE'RE GETTING CLEARLY
THIS FOG COMING UP,

BUT IF THERE WAS A LARGE
CIRCULATORY SYSTEM

THAT'S CONNECTED TO SOME CAVERN
OR FRACTURE NETWORK...

YEP.

...IT WOULD HAVE
WHISKED THIS SMOKE OUT

IN NO TIME FLAT, I THINK.

I MEAN, IT'S NOT
DISSIPATING LIKE

THERE'S A HIGH-POWER
FAN IN THERE,

WHICH, IF IT WAS CONNECTED
TO SOME TUNNEL,

LIKE MANY IMAGINE,

THAT'S WHAT YOU WOULD
THINK IT WOULD DO.

WITH NO APPARENT AIRFLOW
FEEDING THIS MINE,

WHAT ELSE COULD EXPLAIN
THE FREEZING TEMPERATURES

NEEDED TO MAINTAIN
ITS ICY INTERIOR?

WE NEED TO RE-EVALUATE.

AS I MAKE MY WAY BACK UP
TO THE SURFACE,

I START TO FEEL THE GROUND
SHAKE JUST BELOW MY FEET.

WHOA.

STEFAN AND I HAVE BEEN
GRANTED SPECIAL ACCESS

INTO THE MYSTERIOUS,
AND OTHERWISE RESTRICTED

COUDERSPORT ICE MINE
IN PENNSYLVANIA.

DO YOU SEE IT GOING
INTO ANY FRACTURES?

AFTER COMPLETING AIRFLOW TESTS
INSIDE THE PIT

IN SEARCH OF A COLD SOURCE...

I'M HEADING UP.

...IT'S STARTING TO LOOK LIKE
THE MINE...

WHOA.

...ISN'T THE SAFEST PLACE.

THERE WAS A HUGE ROCK
THAT WAS CANTILEVERED OUT.

WHOA, WHAT HAPPENED?

WELL, THE ENTIRE SHELF
JUST FELL RIGHT BELOW THERE.

OH, MY GOD.

THAT WHOLE PILE DOWN THERE
BASICALLY JUST FELL IN.

THE MINE IS LINED WITH A
SEDIMENTARY ROCK CALLED SHALE.

IT IS COMPOSED OF MINERALS
AND IS FLAKY AND EASY TO CRACK.

AS THE ICE MELTS,
IT FREES UP THE ROCK,

CAUSING IT TO COLLAPSE.

THE LONGER WE'RE IN THERE,
THE MORE DANGEROUS IT BECOMES.

YOU CAN HEAR IT
FALLING STILL.

- YEAH, YEAH, YEAH.
- IT'S STILL FALLING.

WE SHOULDN'T GO
DOWN THERE.

THAT'S PROBABLY 1,000 POUNDS
OF ROCK THAT JUST FELL.

IT'S DEFINITELY
AN ACTIVE PIT.

ALL RIGHT.

WE'RE GOING TO HAVE TO USE
SOME HIGH-TECH EQUIPMENT

TO SOLVE THIS MYSTERY,

AND I KNOW JUST
THE RIGHT PEOPLE TO GO TO.

WOW,
LOOK AT THIS PLACE.

FINALLY MADE IT
TO THE LAB.

YEAH.

YOU READY TO GEEK
OUT A LITTLE BIT?

YEAH, I'M REALLY EXCITED
TO CHECK IT OUT,

AND HOPEFULLY, THEY HAVE
SOME TECH FOR THAT ICE MINE.

THE NEXT STOP IN OUR
INVESTIGATION IS TO VISIT

THE UNIVERSITY OF PENNSYLVANIA'S
ROBOTICS TEAM

IN PHILADELPHIA.

HEY.
- HEY, GOOD TO SEE YOU AGAIN.

- HOW'S IT GOING, YASH?
- GOOD TO SEE YOU.

GOOD TO SEE YOU GUYS AGAIN.

WELCOME TO THE GRASP LAB.
- YEAH.

YASH MULGAONKAR IS ONE
OF ITS ROBOTICS EXPERTS.

SO WE HAVE THIS ICE MINE,
BASICALLY,

A LITTLE HOLE
IN THE GROUND

OUT
IN WESTERN PENNSYLVANIA,

AND IT'S REALLY WEIRD
BECAUSE IN THE WINTERTIME,

THE ICE MELTS,

AND IN THE SUMMER,
THE ICE BUILDS.

SO WE REALLY NEED YOUR HELP
BECAUSE WE WANT TO FIGURE OUT

WHY THIS ICE IS FORMING,

BUT WE CAN'T QUITE DO IT
WITH THE TECH THAT WE HAVE.

THE CAVE IS PRETTY DANGEROUS.

EVEN WHILE WE THERE,
THERE WAS THIS LEDGE BROKE OFF,

COULD HAVE CRUSHED US.

DO YOU HAVE SOMETHING
YOU THINK MIGHT WORK IN THERE?

WHAT ABOUT
A FLYING VEHICLE?

THAT COULD WORK.

SO THE SMALLEST ONE
WE HAVE,

THIS IS SOMETHING THAT
I'VE BEEN WORKING ON.

THIS TINY DRONE IS PROTECTED
BY A CARBON-FIBER CAGE

IN CASE IT COLLIDES
WITH ANYTHING.

LET'S MAKE IT FLY.

YOU'RE GONNA MAKE
IT FLY RIGHT NOW?

YES. READY?

3, 2 AND 1.

- WOW.
- OH, MY GOSH.

LOOK AT THAT.
- THAT'S AWESOME.

THAT IS COOL.

WHAT DO YOU THINK?

I'M IMPRESSED.

OH, WOW.

SO THIS WILL GIVE YOU
A VIDEO

OF WHAT THE MINE LOOKS
LIKE FROM THE INSIDE.

OKAY.

YEAH, WE'VE ALREADY DONE
A VISUAL SURVEY.

WELL, THIS IS COOL, BUT I THINK
WE'RE GONNA NEED SOMETHING

THAT CAN SCAN THE ROOM
AND GET A DETAILED MAP OF IT.

OKAY.

WE HAVE ROBOTS THAT HAVE
A HIGH-RESOLUTION LiDAR.

IT'S GOT BEAMS

AND CAN SPIN
ALL 360 DEGREES AROUND.

OH, OKAY.

LiDAR STANDS FOR LIGHT
DETECTION AND RANGING.

IT USES PULSES OF LIGHT
TO SCAN SURFACES IN FINE DETAIL

THAT WOULD OTHERWISE GO UNSEEN.

I THINK WE NEED A LiDAR UNIT
LIKE THIS...

MM-HMM.

...BECAUSE IT'LL GIVE US
THE RESOLUTION WE NEED.

THIS WILL CREATE THE FIRST-EVER
3-D MAP OF THE CAVE.

IF THERE IS A CAVITY
ON THE OTHER SIDE OF THE WALL

OR A WATER SOURCE
LEADING INTO THE MINE,

THE LiDAR SHOULD BE
ABLE TO DETECT IT.

- WE HAVE THE TRUCK...
- OH, YEAH.

...SO WE COULD USE
THE RC TRUCK AS A BASE.

- YEAH.
- LOOK AT THAT.

WE HAVE A HANDHELD LiDAR,

BUT THE CAVE IS TOO DANGEROUS.

WE NEED SOMETHING TO HELP US
OPERATE IT REMOTELY.

ALL RIGHT.
LET'S GET TO WORK.

BY ATTACHING THE LiDAR
ONTO THE TRUCK,

THIS MAKESHIFT MACHINE WILL BE
ABLE TO SQUEEZE INTO TIGHT SPOTS

AND DETECT ANY OPENINGS
BEHIND THE CAVE WALLS.

OKAY.

SOUNDS LIKE IT'S EXACTLY WHAT
WE NEED TO SOLVE OUR PROBLEM.

- YEAH, IT'S PERFECT.
- ALL RIGHT.

I THINK WE HAVE A ROBOT
THAT WE LIKE.

- OKAY.
- SO SHOULD WE GO TEST IT OUT?

- LET'S TEST IT OUT.
- OKAY.

WILL THIS ROBOT
BE ABLE TO NAVIGATE

THE ICE CAVE'S ROCKY BOTTOM

IN ORDER TO CREATE A MAP

EXPLAINING HOW THE ICE
IS CREATED?

AW, SO CLOSE.

STEFAN AND I ARE BACK
AT COUDERSPORT ICE MINE

WITH A LiDAR UNIT ATTACHED
TO A REMOTE-CONTROL TRUCK.

GOT IT.

WILL OUR HIGH-TECH DEVICE
FINALLY REVEAL

THE COLD SOURCE
INSIDE THE ICE MINE,

OR WILL THIS CENTURY-OLD MYSTERY
REMAIN AN UNSOLVED PUZZLE?

ARE YOU GUYS READY?

OKAY, WE GOT A POINT CLOUD.
AND WE ARE GOOD TO GO.

THE LiDAR WILL SPIN AROUND,
USING LASERS TO SCAN THE CAVE.

WE'LL BE ABLE TO USE
THE READINGS

TO CREATE THE FIRST-EVER
3-D MAP OF THIS ODD PLACE,

POINTING OUT ANYTHING
THE AIRFLOW METER

OR SMOKE MACHINE
COULDN'T PICK UP.

IT WILL ALSO PROTECT US
FROM BEING CRUSHED

BY CRUMBLING ROCKS.

HOW IS IT LOOKING OVER THERE
WITH THE LiDAR?

IT LOOKS GOOD.
YOU GUYS ARE...

YEP, GOOD DRIVING.

THERE'S THIS ONE SIDE
THAT'S A LITTLE SLIM

IN TERMS
OF ITS POINT CLOUD.

- UH-HUH.
- WE NEED TO FILL IN THIS GAP

THAT'S ON THE OPPOSITE
SIDE OF THE ICE CAVE.

OKAY, SO YOU CAN SEE HERE,
YOU JUST GOT TO GO STRAIGHT,

AND YOU'LL GET
AROUND THE LADDER.

THE TERRAIN IS TRICKY, EVEN
FOR THIS REMOTE-CONTROL TRUCK.

- AW, SO CLOSE.
- THERE IT IS.

NICE.
ALL RIGHT.

LET'S GRAB THE ROBOT,

AND WE'LL HEAD BACK
TO THE LAB...

- AWESOME.
- ...LET YOU GUYS PROCESS IT.

NOT BEING ABLE TO
UNCOVER ANYTHING

WITH OUR PREVIOUS TECH

HAS ONLY HEIGHTENED
MY CURIOSITY,

BUT WILL THE LiDAR
FINALLY REVEAL

HOW THE ICE FORMS DURING
THE HOT SUMMER MONTHS

WHILE MELTING IN THE WINTER?

THIS IS EXCITING.

IT'S, LIKE, ALL THAT WORK
FINALLY COMES DOWN

TO PROCESSING IT.

YEP.

YEAH, WE'RE HOPING
THAT THIS ILLUMINATES

THE SUBJECT A LITTLE BIT BECAUSE
WE RAN INTO SO MANY ROADBLOCKS

THROUGHOUT THIS
ENTIRE INVESTIGATION.

SO HOPEFULLY,
OUR CUTTING-EDGE MAP

WILL HOLD THE ANSWERS.

ALL RIGHT.
SO HERE WE GO.

LET'S GET THIS THING OPENED.

ARE WE ALL READY?
WE ALL READY?

HERE IT COMES.

- OH.
- COME ON.

COME ON.

HEY, LOOK AT THAT.

THAT'S ACTUALLY
A GREAT ANGLE.

THIS IS UP
LOOKING DOWN INTO...

IMMEDIATELY, WE NOTICE
SOME FASCINATING POINTS

ON OUR 3-D MAP.

WOW.
- LOOK AT THAT RIGHT THERE.

THESE POINTS REPRESENT
SMALL EMPTY CAVITIES

JUST BEYOND OUR REACH
INSIDE THE WALLS.

SO IT LOOKS LIKE WE HAVE
SOME POINTS OVER HERE

TO THE SIDE THAT REALLY DIG OUT.

ACTUALLY, OH.
THAT'S A BIG AMOUNT OF POINTS

THAT ARE OUTSIDE
OF THE NORMAL WALL.

THAT IS UNUSUAL.

COULD THESE POINTS
BE A FACTOR IN HOW THE MINE

MAINTAINS ITS FRIGID
TEMPERATURES IN THE SUMMERTIME?

SO WE'RE SEEING POINTS, HERE,
THAT EXIST OUTSIDE OF THE CAVE

THAT WE WERE IN,

AND, YOU KNOW, THIS LiDAR
LASER SHINES THROUGH

AND THEN BOUNCES BACK
AND STORES A POINT FROM OUTSIDE.

THAT MEANS THAT'S AN OPENING
THAT WE WEREN'T ABLE TO SEE.

YEP.

THAT'S PRETTY GOOD PROOF OF
A FISSURE AND FRACTURE NETWORK

THAT MIGHT LEAD TO WHAT'S
FEEDING THIS COLD SPOT.

WELL,
THIS IS ENCOURAGING.

WHAT WE HAVE UNCOVERED
MIGHT ACTUALLY BE THE ANSWER

TO THIS LOGIC-DEFYING CAVERN.

OUR CUTTING-EDGE MODEL
HAS REVEALED

LITERALLY THOUSANDS OF
TINY FISSURES AND CREVICES

IN THE CAVE WALLS,

WHICH SUGGEST THE POSSIBILITY
OF A NEW THEORY.

WHEN WINTER ARRIVES,
THESE EMPTY FISSURES TRAP

IN THE NATURAL COLD AIR.

THE CAVITIES HOLD ONTO THIS AIR,

KEEPING THE MINE CHILLY
THROUGHOUT THE SUMMER MONTHS.

AS THE COLD TEMPERATURES
WITHIN THE FISSURES FADE,

IT THEN BEGINS TO TRAP
THE HOT SUMMER AIR,

ENSURING THE CAVE IS
WARM ENOUGH TO MELT AWAY

ANY ACCUMULATING
SNOWFALL IN THE WINTER.

IN OTHER WORDS, THE WALLS
THEMSELVES ACT LIKE AN ICE PACK

INSIDE A LUNCH BOX,

BUT IN THIS CASE COLD ENOUGH TO
CREATE THE ICICLES WE HAVE SEEN.

COOLEST ROBOTICS TEAM
WE KNOW.

YEAH.

AND WE'LL DEFINITELY
BE BACK.

WE WILL
DEFINITELY BE BACK.

YOU'RE MORE THAN WELCOME
TO COME BACK ANY TIME.

AWESOME.

WHETHER IT'S
AN UNDERGROUND NETWORK

OF FUNGI-INFESTED TREES

CAUSING A TRAGIC ACCIDENT
ON THE SHORES OF INDIANA,

OR A SERIES OF
MICROSCOPIC FISSURES

TRAPPING COLD AIR IN THE RURAL
MOUNTAINS OF PENNSYLVANIA,

SOMETIMES, THE ANSWERS
TO OUR QUESTIONS ARE HIDDEN

JUST BEYOND OUR REACH.