Original subtitles

[dramatic music]

- [Danny] Mysteries can be buried anywhere,

under the earth,

[deep explosion]

[engine whirrs]

beneath the sea,

[plane whooshes]

or even right under our own feet.

[coins jingle]

[dramatic music]

And when we stumble upon them,

sometimes what we find can change history.

[dramatic music]

Tonight,

the discoveries get wild.

[explosion banging]

From a secret cave.

- [Paul] They find 40-foot crystals,

ghost white and razor sharp.

- The caves are a death trap.

- [Jenn] I mean, if one breaks loose,

you don't stand a chance.

- [Danny] To a frozen underworld.

- [ Kavitha] Researchers expected a complete dead zone.

Instead, they found an entire ecosystem.

- [Danny] To a loyal pup who helps crack a cold case.

- [Adam] People are feverishly looking for the trophy.

And he thinks his dog Pickles may have just found it.

- Join us now because nothing stays hidden forever.

[dramatic music]

Grocery stores aren't usually a place

for jaw-dropping finds,

but this one held a surprise no one was prepared for.

- [Andrew] It's 1996 and a biologist named Robert Timmins

is doing field work in Laos.

He takes a break for lunch

and he goes to an open air market.

As he's checking out the meat and the produce,

he notices something unusual for sale.

[dramatic music]

It's a long-whiskered rodent.

[dramatic music]

- [Sami] These rodents are unlike anything

Timmins has ever seen before.

They're about 10 inches long,

they've got very short limbs, unusual-looking teeth.

Timmins takes a look at these rodents

and actually thinks that they kind of look like a cross

between a rat and a squirrel.

Now the locals call

this particular type of rodent kha-nyou

and they also say that they're pretty tasty.

[dramatic music]

- [Hakeem] They're cheap, so

he spends about six cents

to buy two of them, but not for dinner,

because he's convinced

that there's something unusual about them.

He starts calling them

Laotian rock rats

and he sends them to the Natural History Museum in London

so they can take a closer look.

- [Danny] When scientists examine them, they're stunned.

It's something they've never seen before.

- [Andrew] DNA tests reveal that they do not match up

to any other animal on the planet.

This isn't just a new species,

this is entirely new family of animals.

- [Hakeem] This kind of find is unheard of these days.

The Laotian rock rat is given an official name,

Laonastes aenigmamus, which translates to

inhabitant of stone, enigmatic mouse.

And the findings are published

in the Journal of Systematics and Biodiversity.

[dramatic music]

- [Danny] But when researchers

at the Carnegie Museum of Natural History

come across the new study,

something about this strange creature looks very familiar.

- [Sami] Photos of the rodent look very similar to a skull

that the museum has in their collection

from an animal that's been extinct for 11 million years.

[dramatic music]

- [Andrew] They do a side-by-side comparison

of the living rodent's skull

with the extinct skull in their collection.

And when they look

at them side by side,

they find a perfect match.

Other things like the tooth enamel and molars, also a match.

- So it turns out that Robert Timmins

didn't discover a brand new species,

he just stumbled upon one that we thought was long gone.

- [Danny] It's what scientists refer to

as a Lazarus species.

- Probably the most famous example of a Lazarus species

is the coelacanth.

This is a fish that is weird looking,

and most researchers thought it went extinct

back with the dinosaurs.

- [Andrew] Then in 1938, a fishing boat

off the coast of South Africa

pulls one out of the water,

very much alive, flopping around in their boat.

So the rodent in this meat market in Laos

is kind of like the coelacanth of rats.

- [Danny] But if this coelacanth of rats

has been around all this time,

how did it manage to stay hidden for millions of years?

- The truth is that this particular species of rat

wasn't even on the radar of scientists at all

until Timmins comes across it in the open air market.

But to the locals in Laos,

they've known about this rat for quite some time.

They just have a different name for them.

- [Andrew] The locals even share their traditional recipe

for cooking the rock rat with Timmins,

roast it whole,

chew the small bones,

spit out the large ones.

[dramatic music]

- Some discoveries change science.

This next one changes three lives.

- [Paul] In the fall of 1980, 19-year-old Bobby Shafran

is excited to start his first day

at the Sullivan County Community College

in the Catskills region of New York.

He's ready to start a new chapter in his life.

But almost immediately,

things feel off.

- [Andrew] Students he has never met before

start greeting him like an old friend.

They hug him, kiss him,

and most disconcertingly, call him by the wrong name, Eddy.

- [Hakeem] Even one of Bobby's dorm mates

makes the same mistake.

In fact, this person is so shocked

at how close Bobby looks to his friend, Eddy Galland,

he has to get them together.

So he pulls Bobby into a payphone and they call Eddy.

[phone ringing]

And when Bobby hears Eddy

through the other end of the phone,

it's like he's listening to his own voice.

- [Danny] During that conversation,

the two men make a wild connection.

- [Andrew] Bobby asks Eddy if he was adopted.

He says yes.

Then Bobby asks Eddy his birthday.

July 12th, 1961.

This is when Bobby knows

that this isn't just some coincidence.

He has found his twin.

[dramatic music]

- [Hakeem] The two meet in person,

and the similarities are uncanny,

the same face, the same laugh,

even the same birthmarks.

They bond instantly.

- [Paul] Word of their heartwarming story spreads fast,

with newspapers publishing pictures

of the two new found identical twins side by side,

grinning ear to ear.

- [Danny] Then the story gets even more outrageous.

- A third teenager,

David Kellman, reads these stories,

and to him it's like looking in a mirror,

or really two mirrors.

And when the three boys finally meet,

it becomes clear they're not twins,

they're triplets.

- [Danny] But the deeper they look into their history,

the stranger it gets.

The triplets soon learn they weren't placed apart by chance.

The boys were intentionally separated at birth.

- [Jenn] The boys were part of a secret study

led by psychiatrist Peter Neubauer.

The experiment hoped to observe

how genetically identical siblings

might develop differently if raised apart.

- [Paul] It was the ultimate test

of the nature versus nurture debate.

Between the early 1960s and 1980s,

11 sets of twins, plus the triplets,

were sent to different homes,

but none of the parents and none of the children

were told that they were

part of an experiment.

- [Hakeem] The boys grew up under

the watchful eyes of researchers,

who visited regularly,

under the guise of normal developmental check-ins

for adoptive children.

But in reality, they were administering IQ tests,

personality assessments,

and filming it all.

- [Danny] The study was supposed to remain secret,

but the triplets' unplanned reunion

forces it into the light.

- Once the truth comes out, the backlash is immediate.

The families are outraged, the public is horrified,

and the scientific community is shaken.

The idea that people's lives

were being manipulated in this way without their consent

is a significant ethical, moral,

and legal problem.

And in 1980, this study is still ongoing.

- [Danny] As the controversy swells,

Dr. Neubauer is forced to finally shut down the study.

- [Paul] The triplets and the other test subjects

fight for years

to keep their personal files out of the public eye.

Eventually, under threat of a lawsuit,

the scientists decide not to publish

any of their findings at all.

- [Andrew] In 1990, these scientists agree

to seal all of their files

and essentially lock them in a vault at Yale University.

They can't be legally opened until 2065,

when both the scientists and the subjects

are likely to be long dead.

- [Hakeem] Whatever those files end up revealing

around the question of nature versus nurture,

the story of Bobby, Eddy, and David

shows you how a simple chance encounter

can shine a spotlight on the shadowy side of science.

[dramatic music]

- Most dog walks are uneventful,

but for one man and his pup,

their evening stroll becomes the start of a wild mystery.

[dramatic music] [light music]

- [Austin] It's March 27th, 1966 on a cool South London night

and Dave Corbett's dog, Pickles, is begging to go out,

so he grabs the leash,

and he gets ready,

and he heads off down the street.

- [Andrew] They're not far from home

when Pickles yanks on his owner's leash

and pulls him over to the side of the street.

Corbett assumes that the dog

is simply chasing some strange smell,

but as he gets closer, he sees something unusual.

[thunder rumbles]

- [Jenn] It's this little bundle wrapped up in newspaper

and tied with a string.

Dave peels back a little bit of the paper.

He spots a base, and then there's these words

it says Brazil, West Germany, and Uruguay.

So he peels back a little more paper

and he sees a small golden statue

of this woman holding a bowl above her head.

[dramatic music]

- He has seen this before in newspaper articles

that are all about the recently stolen World Cup trophy.

And he thinks his dog Pickles may have just found it.

- [Danny] So how did one of the most famous prizes in sports

end up on a street in London?

- [Austin] A week earlier, this trophy, the Jules Rimet Trophy,

was on display at Methodist Central Hall in Westminster.

England is about to host the World Cup

and they wanna show their trophy off.

- [Adam] On March 20th, somehow, in broad daylight,

a thief, or thieves,

stole the World Cup in front of everyone.

- At about 11 o'clock to 12 o'clock this morning,

the thieves got in by forcing one of the inner doors.

- [Adam] Everyone in England from every walk of life

is offering rewards

for the safe return of the World Cup trophy

and a nationwide manhunt is on.

The uproar is global.

Scotland Yard is involved and

people are feverishly looking

for the famous trophy.

- [Andrew] When Dave walks into his local police station

and places the missing trophy down on the sergeant's desk,

he thinks he'll get a thank you, maybe even a reward,

but that's not what happens.

- Instead of a hero's welcome, they haul him in.

They throw him in a car,

they drive him down to Scotland Yard,

and they grill him.

Good Samaritan Dave is now

the prime suspect in the theft.

- We can appreciate how

from the police perspective,

Dave's story might seem farfetched.

The entire law enforcement apparatus of the nation

has been mobilized to find this missing trophy,

and this man's dog just happened to sniff it out

one night on a walk?

But Dave knows he's done nothing wrong.

He sticks to his story

and eventually the police let him go.

- [Jenn] The police speculate the real thief got scared

with all of the media attention,

panicked, and then ditched the trophy

where he thought nobody would find it,

except he wasn't counting on Pickles.

- [Danny] Overnight, Pickles becomes

an international celebrity.

- [Austin] He's awarded a medal

from the National Canine Defence League.

He gets dog food endorsements.

He presides over the opening of restaurants.

He even gets a film made out of him,

"The Spy with a Cold Nose."

- [Andrew] But the biggest reward comes five months later.

After England defeats West Germany in the World Cup final,

Dave and Pickles are invited to the victory banquet.

And when the trophy is raised,

everybody knows who the true hero is, Pickles,

the little dog who just wanted to go for a walk.

[dramatic music]

- Next up, an even more outrageous find

beneath our nation's capital.

- [Hakeem] September 26th, 1924,

a truck driver is making a delivery

near Dupont Circle in Washington DC

when something strange happens.

As he drives through a back alley,

the rear of his truck suddenly drops beneath him.

[truck banging] [wheels screeching]

- The driver slams on the brakes, jumps out,

and sees that the rear wheels of his truck

have sunk into the pavement, into a large sinkhole.

- A crew shows up to help pull out the truck,

but when they look at

the hole more closely,

they find something more than a sinkhole.

- [Hakeem] Beneath the alley lies a manmade tunnel.

It is hundreds of feet long, stretching under the city.

There is no records of its construction

and no one can explain why it's there.

- [Kavitha] Now this isn't some rough put together tunnel.

This is really well built.

It's six feet tall and four feet wide,

and it's even wired with electric lights.

- [Danny] When newspapers catch wind of the story,

it explodes, and so do the theories.

- Some claim to have seen

old German newspapers

on the walls of the tunnel,

which sparks rumors that what they've discovered

is some kind of hideout for German spies during World War I.

Still others think it was built to smuggle alcohol,

this being during Prohibition.

- There's even a claim that the tunnel

dates back to the Civil War

and was used by Confederate soldiers

hiding in Union territory.

- Reporters start digging into the property's past.

The current owners know nothing,

so they look into the previous owner,

who was a Smithsonian entomologist,

an insect scientist,

named Harrison Dyar.

- [Hakeem] Dyar is brilliant and passionate,

with an obsessive streak

that drove his work to extraordinary lengths.

- [Kavitha] Over the course of his career,

he would name 3,000 species

of butterflies and moths.

Over 600 species of mosquitoes

and 70 species are named after him.

- [Andrew] In 1917 alone,

he donates 44,000 insect specimens to the Smithsonian.

So in the field of entomology,

Dyar is a giant.

[dramatic music]

- [Danny] But that same year,

Dyar's carefully curated life starts to crack

when his wife files for divorce.

- She found out that Dyar was living a double life

and had a secret family

with a school teacher named Wellesca Pollock.

Together they had three children,

none of whom were known to his legal wife.

- [Danny] Investigators initially believe

the tunnel may be connected to Dyar's hidden activities,

but the explanation they get is far stranger.

- [Andrew] When questioned,

Dyar admits to having dug the tunnel himself by hand

over the course of a decade.

Why?

He says it was a hobby and a form of exercise.

- [Kavitha] Some wonder if the tunnel was a way for Dyar

to move between the two families without being noticed.

Others think it was just his ultimate man cave.

[dramatic music]

[dramatic music]

- Deep underground,

two miners are hunting for precious metals,

but what they break open instead

is something far more dangerous

than anything they ever imagined.

- [Hakeem] In April 2000,

two brothers, Eloy and Javier Delgado,

are working in the Naica Mine in Mexico.

They're prospecting for zinc and silver,

so they're setting charges in a tunnel

in order to open up new rock.

- After they set the explosives,

they retreat to a safe distance

and then hit the trigger.

[explosion banging]

The explosion rips through the tunnel,

sending rocks and debris everywhere.

After everything settles, the brothers approach

to see what they found.

- Unfortunately they don't find any zinc or silver,

but they do find something unusual,

a small hole in a portion of the rock wall.

- [Danny] As Eloy squeezes through,

he's hit with overwhelming heat and humidity.

- He wipes the sweat from his eyes

and shines his light

into the cavern,

and he is stunned.

He has just opened up a gigantic cavity.

And filling this cavity

are these monstrous,

ghost white crystals.

Some are as big as tree trunks,

up to 40 feet tall and 6 feet wide.

It's like he walked into Superman's Fortress of Solitude.

- [Jenn] The Delgado Brothers report their remarkable find

to their bosses at the mining company,

who then call in geologists to research it.

- [Danny] As experts descend

into the newly named Crystal Cave,

they quickly learn its beauty

hides conditions unlike anything they've ever faced.

- It's so hot it feels like you're entering a blast furnace.

It's over a thousand feet underground,

and down there the temperatures are as high as 140 degrees

and the humidity reaches a hundred percent.

At those temperatures and that level of humidity,

your body's sweating mechanism can't keep you cool enough.

- [Paul] It's so humid that when you inhale,

the hot, humid air enters your lungs

and then condenses the same way it condenses

on a cold glass of water.

But this is happening inside your lungs,

so it ends up drowning you from the inside out.

- These caves are literally a death trap.

Researchers, in order to go in and safely work,

they have to wear special ice-cooled suits

with breathing systems that bring them cool, dry air

in order to survive.

- [Jenn] Then there are the crystals themselves.

I mean, they are razor sharp, slippery,

and some weigh as much as 55 tons.

So, I mean, if one breaks loose,

you don't stand a chance.

- [Danny] What shaped these crystals

and makes them so dangerous comes from far below the cave.

- The researchers eventually discover that the cavern

sits above a fault line and magma reservoir.

Around 26 million years ago,

the magma squeezed out of its reservoir

and forced scalding hot water

up into the porous limestone,

which carved out this cavity.

- The water contained gypsum.

And when the temperature of the water dropped,

the gypsum began to crystallize.

- [Danny] But crystals weren't the only things

forming in the cave's harsh conditions.

- In 2017, the cave reveals another of its mysteries

when NASA scientists find ancient bacteria,

tens of thousands of years old,

trapped within these crystals.

They retrieve samples

and bring them back to life in the lab.

[dramatic music]

- [Danny] The bacteria are called extremophiles,

microbes that evolved to survive where nothing else can.

And scientists believe they could provide insight

into how life might exist on other planets.

[dramatic music]

- [Hakeem] The Crystal Cave is a natural wonder,

and if life can survive there,

maybe we're not as alone as we think.

[dramatic music]

- If you thought surviving that kind of heat was crazy,

wait till you see what's living under Antarctic ice.

- [Paul] On January 13th, 2025,

an international team of oceanographers

are working off of the coast of Antarctica

in the Bellingshausen Sea.

[ice shelves cracking]

Their mission is to study the shrinking ice shelves

and how that's impacting climate

and sea levels around the world.

- [Kavitha] Midway through their expedition,

the team receives breaking news.

An iceberg the size of Chicago

has broken off the George VI Ice Shelf.

[ice shelf rumbling]

It exposes more than 200 square miles of sea floor,

and by sheer luck, they're only 57 miles away.

- This is a rare opportunity

to study part of the sea floor

that has been hidden for centuries under 500 feet of ice.

So the team deploys

a remote-operated underwater vehicle with cameras

[water splashing] [air bubbling]

to go down 4,000 feet and investigate.

- [Danny] As the submersible

sweeps across the newly exposed sea floor,

the first images stream back to the ship,

revealing something the crew never expected to see.

- [Austin] This should be a barren wasteland,

but almost immediately the camera reveals a crab

walking over a sponge.

[dramatic music]

As the sub sends more pictures,

more and more life comes into view.

- [Kavitha] The ocean floor is covered with sponges and corals.

The scientists have discovered

a thriving underwater ecosystem,

which is baffling to them because this isn't the tropics.

This is thousands of feet below the coast of Antarctica.

- [Andrew] There are sea spiders, ice fish, octopuses.

They even see an extremely rare phantom jellyfish,

three feet wide, with tentacles trailing 30 feet behind it.

- [Kavitha] Based on how big and developed these creatures are,

the scientists realized

that they didn't just show up recently.

They've been chilling under the ice for centuries.

- [Danny] But if this place has been sealed off

for hundreds of years,

how is anything still alive down here?

- [Paul] All of these organisms need food to survive.

That food system is based on plant and algae

on the surface of the ocean

getting energy from sunlight,

and then other animals eat those organisms and then die,

and then all of that material,

all of that organic matter and food,

drift down to the bottom of the ocean,

where they supply a source of energy

for everything living at the bottom.

But this region has been cut off

from the usual food chain systems

that exist in oceans throughout the rest of the world.

- [Austin] Some scientists theorize that

deeper ocean currents

are carrying that organic material from somewhere else,

while other scientists feel

that the surface contact ice is melting

and ancient organic material trapped there for centuries

is trickling down.

- [Danny] Either way, food is still reaching

this hidden ecosystem just enough to keep it alive.

- This site alone is home to over 60 species,

some of which were unknown to science previously.

So who knows what's hiding under the ice

in other regions of the world?

There's certainly a lot more to discover.

[dramatic music]

[dramatic music]

- Cutting the grass is just another chore,

until the mower turns up something

that hasn't seen daylight in 70,000 years.

[dramatic music]

- [Andrew] In the fall of 2024,

a homeowner in Scotchtown, New York

is doing some last minute landscaping

before winter sets in.

As he tends to his flower beds,

and rakes leaves, and mows the lawn,

he notices something sticking out of the dirt.

[dramatic music]

- [Don] At first he thinks it might be an old baseball,

but when he digs it out,

it looks like two strange fossilized bones.

They're both oval-shaped,

about seven inches long,

and each has a serrated edge on one side.

- [Austin] Curious, he digs deeper and he uncovers two more.

They don't look like any animal he's ever seen,

so he calls the local college for help.

- [Danny] Professor Cory Harris,

an anthropologist at SUNY Orange, takes the lead.

And when he sees the bones in person,

he knows exactly what he's looking at.

- They're not bones,

they're massive teeth,

molars that once belonged to mastodons.

[mastodons roaring]

Mastodons are long- extinct cousins

to mammoths and modern elephants.

And between 10,000 and 14,500 years ago,

they roamed the ancient forests

of what is now New York state.

- [Metin] They are built like tanks at 10 feet tall

and over six tons, and

they've got these long tusks

that can reach a length of over 16 feet long.

- [Andrew] Now that 16 feet is pretty remarkable.

It would've made mastodons a fearsome sight.

[mastodons roaring]

And the mastodon's molars were just as unique.

They are cone-shaped,

which is perfect for this large herbivore

to crush leaves, and twigs, and branches.

[dramatic music]

- [Danny] Over the next few weeks,

Harris and a team of archaeologists

conduct a full dig.

By the end of it, they've recovered a full jaw,

part of a rib, and a toe.

- A find like this is always exciting,

but believe it or not,

backyard mastodons are not unique

in this part of the country.

Orange County, New York

is known as a mastodon fossil hotspot.

[dramatic music]

- [Don] They've been turning up here since 1705.

When locals found huge bones,

they attributed to a race of human giants

described in the Bible.

Over the years, over 150 specimens

have been uncovered in Upstate New York

and half of them from the region around Orange.

- [Danny] It's not just a coincidence,

there's a scientific explanation behind this.

- [Andrew] Some scientists think that the prevalence

of the mastodon in this area

came down to the mastodons' behavior

and especially its diet.

Around 14,500 years ago,

the end of the last ice age,

this area of Upstate New York

would've been a kind of prehistoric vegetarian buffet,

rich with pine, and spruce, and dense underbrush,

all things that mastodons love to eat.

- [Don] Lured here by the ample food on offer,

when an animal died,

they sank into the oxygen-poor peat bogs

that were created by the retreating glaciers.

And those conditions

preserved their remains almost perfectly.

- [Andrew] Every discovery brings us closer

to understanding these prehistoric giants

who once called New York State home.

[mastodon roaring] [dramatic music]

- [Danny] Over 5,000 miles away,

another Ice Age discovery resurfaces,

only this one looks a lot friendlier.

[dramatic music]

- [Don] It's the summer of 2018

near the Indigirka River in Siberia.

Locals are out in the forest,

combing through the ground

looking for mammoth tusks.

- [Andrew] This is the time of year when the permafrost

softens up just enough to reveal bones

that have been locked in the frozen ground

for thousands of years.

And this includes mammoth ivory,

which is incredibly valuable.

- One day, a local stumbles upon something unexpected.

[dramatic music]

It's not a mammoth tusk.

It's small, it's furry,

and it looks like a puppy.

[dramatic music]

- [Don] The animal is surprisingly well-preserved.

The fur is still there.

You can still see its little paws.

Even the whiskers on the nose are intact.

It looks less like a fossil

and more like a dog frozen in time.

But the locals think it might be ancient,

so they contact a nearby university to take a look.

[dramatic music]

- [Danny] Scientists collect the remains

and start running tests.

When the results come back, they're stunned.

- Whatever this specimen is, it's not a dog.

And tests seem to reveal that it's not a wild wolf either.

It's somewhere right in between.

- [Don] Scientists have known for decades that the modern dog

evolved from the wild wolf,

but exactly when and where that split actually happened

is one of animal evolution's biggest mysteries.

So these DNA results from the prehistoric Siberian pup

are a very big deal.

- Researchers name the specimen Dogor,

which is a local Yakut language word for friend.

- [Danny] But the biggest revelation comes

when Dogor is carbon dated.

- Tests reveal that this dog is about 18,000 years old.

Scientists had placed the window of time

when the wild wolf was domesticated into the modern dog

somewhere between 15,000 and 40,000 years ago.

So at 18,000 years,

we know that we're dealing with something closer

to the modern end of that spectrum.

- [Danny] While this discovery

helps us to further understand

the evolutionary timeline between the wolf

[wolf howling]

and the modern day dog,

how that transformation occurred

is still up for debate.

- [Don] One theory is that early humans

took in wolf pups and raised them.

Another idea suggests that some less aggressive wolves

just started lingering around the camps, scavenging scraps,

and over generations, the tamest of them all adapted,

changing from predators to partners.

- In Dogor's short life, no one is sure

if he lived with humans or he lived in that fringe world

between domestication and wildness.

- [Don] Scientists are still studying him.

And as the permafrost melts

and more and more of the prehistoric world

rises to the surface,

this may be just the beginning.

And the actual first dog ever could be somewhere close by.

[dramatic music]

[dramatic music]

- During the Cold War, every sound could mean danger,

but one mysterious noise

is something far stranger than enemy fire.

- [Andrew] June 8th, 1982, it's the height of the Cold War

and tensions are rising along the east coast of Sweden.

The year before, a Soviet submarine had wrecked,

just off the coast.

And now a civilian reports seeing

what they think is a periscope

just off the coast in the Baltic Sea.

- [Austin] The Swedes fear

it could be another Soviet submarine,

so they dispatch patrol boats to take a look.

- [Sami] Sure enough, once they make it out

to a certain portion of the water,

about 32 miles off the coast of Sweden,

they start to pick up this

sound from underwater.

It kind of sounds a little bit like sizzling bacon,

except significantly louder.

So these patrol boats radio back to the mainland,

and within a few minutes,

helicopters are flying to the location

and hovering over that spot.

- [Austin] The Swedes aren't sure if this is espionage

or an act of aggression,

but they're not taking any chances.

The helicopter drops depth charges,

in essence, high explosives that go underwater

to blow up a submarine.

[explosion booming]

If they hit or sink a Soviet sub,

the Cold War is going to get a lot hotter.

[explosion banging] [dramatic music]

- [Andrew] Nearby, the Swedes are waiting

in anticipation of retaliation,

but there isn't any.

And the sound?

It's gone.

- [Sami] The helicopter is searching feverishly,

but they see no signs of wreckage.

They see no debris.

There's no oil slick.

So whatever was producing that sizzling bacon sound

has now disappeared without a trace.

- [Danny] But the silence doesn't last.

Just three days later, the noise is back.

- [Austin] Once again, a Swedish navy patrol hears the signal,

drops depth charges,

[explosion] and then it stops.

It disappears.

A few days after that, it happens again.

- [Danny] Despite repeated efforts to trace the source,

the sounds continue on and off for over a decade.

- [Andrew] Then in 1996,

the Swedish government calls in a civilian

to get to the bottom of things.

- [Danny] Professor Magnus Wahlberg

from the University of Southern Denmark

analyzes the signals for a month

and what he finds is even stranger than they imagined.

- [Austin] The sound from the top-secret Soviet sub

turns out to be

a school of fish,

herring to be exact.

And the strange sizzling, crackling sound

is herring passing gas.

- [Andrew] Herring are modest fish,

shiny, silver, only about 14 inches long,

but they have a remarkable ability that most fish do not.

They can fart.

And when they do, it is loud.

[crackling sound]

- [Sami] Now, most fish have something called a swim bladder,

which, in essence, is sort of like this internal balloon

that helps them to control their buoyancy.

Herring have this as well,

except it's connected to their anus.

So when pressure builds up in this swim bladder,

it's got to go somewhere and it's released through the anus.

[bladder spewing]

You see where I'm going with this.

- [Andrew] Another thing that herring do, or don't do rather,

is travel solo.

They school in massive groups, sometimes in the millions.

And when a school senses a predator,

they form into a tight ball called a bait ball

and they let it rip all at once.

- [Sami] In lab tests,

researchers have recorded the sounds

of herring passing gas sometimes as high as 73 decibels.

That's about the equivalent of an alarm clock

or a vacuum cleaner.

So now imagine the sound of a vacuum cleaner

amplified by a million times underwater.

That's a pretty deafening sound.

- [Andrew] It is a good thing that the Swedes figured this out

before fish flatulence caused World War III.

[dramatic music]

- When a big hurricane hits Florida, the damage is massive,

but what washes up afterwards is the real shocker.

[dramatic music]

- [Hakeem] In the fall of 2019,

Hurricane Dorian tears through Florida's Cocoa Beach,

leaving a trail of destruction.

In addition to ruined houses and flooded roads,

debris starts washing up.

There are broken docks, fishing boats,

even huge 55-gallon oil drums.

[dramatic music]

- [Paul] One day a local resident is walking

along the beach

when they see a lone duffle bag

along with all the other debris.

The duffle bag is covered in seaweed and sand,

and they go to brush it off and unzip it.

And then they freeze.

- Inside the duffle bag,

they find a series of brick-shaped packages.

[dramatic music]

It looks just like a scene out of "Miami Vice."

And if these are what they look like they are,

they're also illegal,

and so they immediately call the police.

- [Danny] Authorities confirm this duffle bag

is holding 15 bricks of cocaine,

with a street value of nearly half a million dollars.

- A few days later, a married couple

is walking along the beach around 20 miles away

when they come upon a plastic-wrapped bundle.

This time it's stamped with the word diamante,

which is Spanish for diamond.

They alert another officer,

and sure enough, it's another package of cocaine.

[dramatic music]

- [Danny] Why is so much cocaine

suddenly washing up across Florida's shores?

- It's no secret that smugglers

are often using the water to ship cocaine.

They're using boats, they're using even submarines.

- [Coast Guard Officer] All right, go, go, go!

[fist banging]

- [Micah] Between late 2024 and early 2025,

the US Coast Guard intercepts almost 24 tons of cocaine

from smugglers at sea.

And that's only what they actually managed to catch.

They're unsure of how much more

might slip through the cracks.

- [Danny] These seaside discoveries

are evidence of drug traffickers risking their supply

to save themselves.

- When storms are on the way,

Coast Guard patrols ramp up.

This puts the heat on smugglers,

who sometimes panic and dump their cargo overboard

to avoid getting caught.

- [Hakeem] Offshore fishermen have a name

for these floating drug bundles.

They call them square groupers.

They often see them floating just beneath the surface,

and most of them eventually sink.

- [Paul] When a massive Category 5 storm hits, like Dorian,

which had 185-mile- per-hour winds,

those groupers get swept along

with everything else in the storm surge

and end up on the coast.

- [Danny] A few years later, another storm blows

the Hurricane Dorian discoveries out of the water.

- In 2024, as Hurricane Debby slams South Florida,

US Customs and border patrol

find about 25 more bricks of cocaine

that have washed ashore 80 miles from Key West.

Altogether, this haul that they've discovered

weighs close to 70 pounds,

with an estimated street value of more than $1 million.

[dramatic music]

- [Hakeem] I mean, these are massive illegal fortunes

just sitting there on the sand.

And technically,

under salvage law, it is finders keepers.

But if you happen to find a duffel bag

full of Schedule II narcotics just sitting around,

finders keepers is not gonna hold up in court.

[dramatic music]

- A resurrected rat, a killer cave,

and life in the most unlikely place,

these are not just your average discoveries.

They're examples of some of the world's wildest wonders.

I'm Danny Trejo.

Thanks for watching "Mysteries Unearthed."