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♪ and may contain mature subject matter.

You know what?

I've been around for a while.

I've traveled the world,

met some interesting people, done some crazy things.

So, you might just think

there's not much that could take me by surprise.

You'd be wrong!

The world is full of stories and science and things

that amaze and confound me every single day,

incredible mysteries that keep me awake at night.

Some I can answer.

Others just defy logic...

like, from the depths of the Pacific Ocean,

one of the loudest

and most mysterious sounds ever heard.

What made it?

Or the residents of a Texas town

who report mysterious lights in the night sky,

UFOs that have the U.S. Air Force in hot pursuit.

What's going on?

And the fishing trawler that disappears,

only to be found undamaged at the bottom of the Pacific.

Why?

Yup, it's a weird world.

And I love it.

1997.

Something emerges from the deep that has

confounded science ever since.

One of the loudest and scariest sounds ever recorded.

Weird, or what?

You know, in the 21st century, we might be forgiven

for thinking that there's no mystery left on planet earth.

If you did think that,

you'd be wrong.

We may have Google-mapped, Facebooked and Twittered

every square inch of land we walk on,

but below sea level,

it's a very different story.

We know more about the depths of the cosmos

than we do about the depths of the Pacific.

This story starts during the Cold War,

when the U.S. Navy implemented

a sophisticated underwater listening grid

to monitor Soviet submarine activity

around the world.

But by 1991, the superpower standoff has ended.

They contact oceanographer Christopher Fox

and offer him and his team the opportunity

to use the system for environmental research.

Christopher Fox: There was an effort in the United States

to see if we could take military systems

and use them for environmental science.

William Shatner: Fox and his team would utilize

the Navy's network of underwater microphones,

known as hydrophones,

that over the years were placed around the world's oceans

in their hundreds.

For the first time, scientists had the means

to listen in to massive areas of the deep sea.

They might wish they'd just left it alone.

Christopher Fox: We began hearing whales.

Of course, we heard shipping and man-made sounds.

William Shatner: But there, amongst the many sounds of the ocean,

was something he had never heard before...

a sound both mysterious and chilling.

We heard it, and then we probably

played it back several times because it was very unusual.

William Shatner: Fox's colleague, geologist Robert Dziak,

was also puzzled by what he heard.

Robert Dziak: To me, the most impressive part

about the sound is how loud it was,

uh, by our, by human standards.

William Shatner: How loud?

What about a whopping 180 decibels,

louder than a supertanker

and one of the loudest sounds ever recorded?

So loud, it was picked up by two hydrophones

over 3,000 miles apart.

Its location was determined to be 50 degrees south,

100 degrees west, just north of Antarctica.

This monstrous and thoroughly weird sound

was nicknamed "The Bloop."

Is that weird, or what?

There's no denying that the Bloop is a very,

very weird sound,

but the thing that has most perplexed scientists

is that after that day in 1997,

the sound was never heard again.

Ever since,

debate as to the origins of this mysterious emission has raged.

Was it geological?

A secret military test?

Or was it biological?

Some kind of very shy beast of the deep?

Christopher Fox: I think it's exciting to think

that there are things going on in the ocean

that we don't know what they are.

William Shatner: So, if the sound is biological, it kind of begs the question --

what on earth, or underwater,

produces a sound this loud?

To produce a sound of this volume,

the animal would have to be enormous.

Blue whales are the largest creatures

that have ever existed on earth,

reaching over 100' in length

and weighing an estimated 400,000 lb.

They communicate in volumes as loud as 185 decibels.

David Mellinger is a marine biologist.

He has analyzed the one-time acoustic event

to see if the Bloop matches with any known biological sound,

like a blue whale.

Blue whales are extremely loud; there's no doubt about that.

Something you can hear at tens or maybe hundreds of miles away

has got to be really loud.

See, I could put them side by side.

Here's the blue whale sound...

(Blue whale singing)

and this one here is the Bloop sound.

(Low sound playing)

Blue whales, even though they're the loudest animal

we know in the ocean

for a continuous, sustained sound,

they're nowhere near as loud as the Bloop sound.

We can hear the Bloop sound for thousands of miles.

The animal would have to be gargantuan

if it were a biological sound.

William Shatner: To find out what produced the mysterious sound,

scientists had to consider a seemingly impossible

and ever so slightly scary prospect,

that blue whales are not the largest creatures in our oceans.

Could there be something else down there?

Christopher Fox: It would be something completely unknown,

and it would probably have to be huge,

and you'd have to say,

"How could something that huge be totally unknown on earth?"

Philip S. Lobel: It really is hard to say

what kind of creature could it possibly be.

There's no question --

we don't know what's at the bottom of the ocean.

The Pacific Ocean is so vast,

it hurts my brain to even think about it.

Here's a body of water covering 30% of the earth's surface,

reaching depths of over six miles.

Think about it.

Anything could be happening down there.

So, if the Bloop wasn't created by a known marine animal,

what about an unknown one?

Could we be dealing with some kind of sea monster,

a remnant of pre-history?

Is it a kraken?

Or a salt-water cousin of the Loch Ness monster?

Sounds crazy, right?

Actually it's not as far-fetched as you think.

In 1938,

a coelacanth was caught off the coast of South Africa.

They were believed to have been extinct

since the end of the Cretaceous period,

over 65 million years ago.

And in 2006,

the remains of a previously unknown

prehistoric marine creature was discovered,

labeled 'Predator X.'

The creature was 49' long

and would have weighed 99,000 lb.

Yikes!

So, is it possible

that one of these is still swimming around?

It's possible there's some creature out there that's--

that we haven't found yet.

I'm skeptical of that idea

because I think we would have fished one up in a net by now.

Philip S. Lobel: What makes it questionable

as to whether it's a biological sound

was it was only recorded once.

William Shatner: Okay, if the Bloop didn't come from a sea monster,

then what else?

In their search for answers, the scientists have pondered

another seemingly far out possibility.

Could, somehow,

the earth itself have made this incredible sound?

.

William Shatner: Experts are trying to uncover the origins

of a mysterious sound

that came from deep within the Pacific Ocean.

They suspect it wasn't made by an animal.

So, another theory emerges.

Could it have been produced by something geological?

After all, there's a lot of weird stuff going on out there.

The outermost layer of our planet,

the lithosphere, is divided into tectonic plates.

Every year, massive underwater earthquakes

and volcanic eruptions occur along their boundaries

beneath the oceans, and guess what?

They produce massive sound waves.

This is the sound of a resonating volcano,

and it's all very low energy here.

It's almost like a little white/yellow band there.

Again, here's an example of an earthquake,

and it's all low-frequency energy.

But when the sounds of an earthquake and a volcano

are compared to the Bloop,

there is one important difference.

Robert Dziak: What's different about the Bloop

is that it's at a much higher frequency range,

you know, much higher pitch than these natural sounds,

and, typically, earthquakes are really low frequency rumbles

that sound like thunder,

and icebergs, they also kind of sound like thunder,

but they have kind of harmonious tones.

This is a different pitch, higher pitch, like an animal,

sort of like what an animal would make.

William Shatner: Could it be a more anomalous geological sound?

The Bloop was recorded near Antarctica.

Perhaps that could be a clue to its origins.

After all, with global warming,

incidents of ice splitting

have been increasing in the Antarctic region.

Robert Dziak: We see really bizarre sounds coming out of Antarctica

that are caused by the interaction

of these giant icebergs coming off of the mainland.

We see the sounds of ice cracking.

We call them ice quakes.

That's very distinctive too.

William Shatner: Icebergs breaking can be as loud as 193 decibels,

as deafening as the Bloop.

Robert Dziak: Icebergs can be as big as, you know, some big land mass.

They can be 10 miles wide, and they can make ice quakes

that are comparable in size to earthquakes.

This one is the sound of an iceberg tremor.

The iceberg's moving along the sea floor,

scraping along the sea floor,

causes the iceberg to resonate and makes a harmonic sound.

William Shatner: But so far, none of the recordings

have captured a similar sound frequency

to that of the Bloop.

So, if the Bloop isn't biological

and it's not geological,

could it be possible that the Bloop is man-made?

That would explain why we only heard it once.

Now, who would have the resources

to make such a loud sound in the middle of the ocean?

Hmm.

Are you thinking what I'm thinking?

In 2000, many believe that secret Navy sonar tests

were responsible when dozens of whales

beached themselves in the Bahamas.

It is estimated that the Navy's secret sonar transmitters

can generate sound as loud as 215 decibels.

Could the Bloop have been this or another secret military test?

They were putting devices and instruments in the water,

testing underwater explosions,

doing underwater experiments of various kinds.

I don't necessarily believe in conspiracy theories.

I think there's probably a reasonable explanation

for all the sounds we observe in the ocean.

William Shatner: Despite the numerous theories,

no one has proven what caused this mysterious sound.

But scientists are still hoping it will be heard again.

Philip S. Lobel: Will we hear it again?

You know, will the sound reveal

some new mystery of the ocean?

Maybe, but, for now,

the Bloop remains...

weird, or what?

William Shatner: It's a scene straight out of a Hollywood sci-fi blockbuster.

The inhabitants of a Texas town witness the night's sky

set ablaze by colourful UFOs,

seemingly in a dogfight with U.S. Air Force F-16s.

Was this mass sighting really as weird

as an authentic alien visitation?

Right, let's get to work.

It's time to delve into the cutting edge of military tech

and separate hard fact from science fiction.

.

We humans have always looked to the sky

for either our salvation or our doom.

Whether looking for our great guardian angel

or the terrifying invasion of a violent alien race,

we look up for our end.

Well, this is the true story of what happened when,

one night,

the entire population of a small Texas town

looked upward as one and were left thinking...

"Is that weird, or what?"

January 8th, 2008.

The sleepy dairy town of Stephenville, Texas.

Looks nice, doesn't it?

Another peaceful evening for Erath County police officer

Lee Roy Gaitan and amateur pilot

Steve Allen is suddenly destroyed

by a close encounter of the first kind.

Lee Roy Gaitan: When I got out of my car, I saw this bright,

bright light, um...

appeared to be changing colours.

Steve Allen: It was real close, like,

1500' in the air and about 1500' over from us,

and whatever it was didn't make any noise at all.

It was totally silent.

Everyone in the community has accepted

that there was something strange happening

the night of January 8, 2008, in Erath County.

William Shatner: The mysterious light show was witnessed by many others

and by morning,

the whole county is reporting spooky UFO sightings.

You know, you'd always see the UFO shows on TV and, um,

I really didn't believe in UFOs.

I mean, I always thought

there was a legitimate explanation.

Steve Allen: I feel like these are from somewhere besides earth.

I don't think they're from earth.

It was almost like a biblical event.

We couldn't come to a conclusion of what it was.

William Shatner: But for Steve Allen,

the mysterious lights were just the half of it.

He thinks the UFOs were joined in the sky that night

by a far more familiar-looking aircraft.

Steve Allen: We went into the house to figure out what happened,

and somebody called and says they're coming back,

and we ran outside,

and that's when we saw the two F-16s in pursuit.

And I thought,

"Well, why is our government chasing something,

you know, or what are we doing?"

You know, "Are we at war with somebody?"

Or it could be end times,

or a lot of things passed through my mind.

And you know, I kind of made a beeline,

after that, to my house, 'cause I thought,

if there was a problem or something happening,

I wanted to be at my own home with my family.

So, what are we dealing with here?

Well, this clearly isn't one of those stories

we hear about all the time,

where some lone crank experiences an alien visitation,

probably gets abducted and yaddi, yaddi, yadda.

No, what we have here is just--

It's much more interesting.

A UFO sighting shared by dozens,

if not hundreds of level-headed Texans.

You can find them.

So, could so many people

see something at the same time

and all believe it to be a UFO

and it not be the truth?

Cognitive neuroscientist professor Allison Sekuler

specializes in researching how the human brain

interprets everyday events.

She believes there may be a more down to earth explanation

for the mystery of the Texas lights.

Allison Sekuler: Officially,

UFO stands for Unidentified Flying Object.

People don't like "unidentified."

The brain doesn't like "unidentified."

The brain's job is to make sense of the world.

William Shatner: You see, to Professor Sekuler, eyewitness statements,

especially those of mysterious and hard to explain phenomena

are often innocent misinterpretations.

Allison Sekuler: Different people can look at exactly the same thing

out in the real world and see completely different things

because the way that you see the world

is not actually a reflection of what's physically out there.

It's a reflection of how that information

interacts with your brain.

And so, because my brain has different sorts of perspectives

on the world and different experiences,

I'll interpret something differently

than someone standing next to me

who's had a different sort of life experience

and a different perspective on what they're looking at.

William Shatner: So, apparently, when faced with something new,

the brain will look for answers

by trying to match what we're seeing

with something similar from our previous experience,

memory and cultural background.

And of course, in the United States,

seeing strange lights in the sky can only mean one thing.

Movies can have a big impact

on the way that we think about and see the world.

So, if there hadn't been

a whole flurry of UFO movies in recent history,

it'd be less likely that all these people

would have said, "Ah, it's a UFO."

I'm not saying I saw a UFO,

but with all the reports from everybody else,

apparently, that's what I saw.

Okay, so, when it comes to finding

a rational answer for something weird,

we humans might just form a consensus that's based,

subconsciously, on what we've seen in movies

or read in comic books when we were kids.

So, given the right light,

angle and conditions,

someone seeing an innocent Frisbee

flying through the air

might process it as something altogether different.

So, whatever the people of Stephenville saw that night

may not have been an alien spacecraft,

but the fact remains, they saw something,

something very weird.

What was it?

James McGaha: There is no evidence

that the earth has been visited in the past

or is being visited today by extraterrestrial aliens,

no evidence whatsoever.

William Shatner: James McGaha is a retired Air Force pilot

and a complete skeptic about alien visitation.

What a spoilsport.

As far as he's concerned, he knows exactly

how to explain the mysterious lights.

They were military flares.

This is Stephenville right here.

Here's where the aircraft were flying that night.

At the exact time they were saying

they saw lights in the sky,

there were eight F-16s in the area, flying maneuvers,

both with after-burners, which produce lights,

with their formation lights on,

and they were dropping flares.

William Shatner: Now, you see, flares are used by the Air Force

to solve two different yet equally important problems.

One, there are ground illumination flares.

These flares are dropped from aircraft

in order to light up an area on the ground

several miles wide.

The flares are suspended in the air by a parachute.

The heat from the flare helps to keep it aloft.

Two, there are countermeasure flares.

This kind is used to confuse enemy missiles

targeted onto aircraft.

The heat of these flares

is hotter than the heat from the afterburner,

causing heat-seeking missiles to lock onto and track the flare

instead of the military jet.

Huh, interesting.

The aircraft were manoeuvring all around.

The flares were being dropped.

So, there was lights and everything.

It would be very difficult for someone,

unless they knew exactly what the military manoeuvres were,

to actually understand who was chasing what.

Okay, I've got to admit,

flares being dropped from F-16s in war-game exercises

seems like a plausible

explanation for the Stephenville lights,

but for some,

this theory just doesn't add up.

Could the US government be covering up the truth?

.

William Shatner: In a mass "Weird Or What" moment,

hundreds of eyewitnesses report UFOs in the skies

above Stephenville, Texas,

being chased by US Air force F-16s.

Can this be true?

What really happened?

Steve Allen is a private pilot.

He saw the lights

and isn't convinced they were simply military flares

dropped by US fighter jets.

Lights we saw travelled at a high rate of speed,

all the way from the east to the west,

and come back by with jets chasing it

and only, like, 1500' off the ground.

So, yeah, what we saw was definitely not a flare.

It was quite spectacular.

They was on the same height and trajectory.

You know, they was following it

or attempting to keep up with it.

You could see the full after-burner

coming out the back of the F-16s.

Probably, you know,

I would say they was running in excess

of 500 or 600 miles an hour, themselves.

William Shatner: Allen's belief that the lights

were UFOs actually being chased by fighter jets

is supported by one crucial piece of information.

If these were simply flares,

why didn't the Air Force admit it?

Steve Allen: Carswell Air Force base and the military in Fort Worth

originally denied anything out here,

and then they denied that F-16s was there.

And of course, they was from here,

no further than two football fields away.

So, we know they was there.

Later on, as I discovered,

there were indeed aircraft flying that night,

and the Air Force, the public affairs office,

put out a press release, saying we made a mistake.

There was nothing more to it,

no, nothing sinister at all to it,

just a mistake.

Hmm.

So, U.S. Air Force claims there was no military activity

in the skies above Stephenville on the night in question

but then mysteriously change their minds a few days later?

Sounds suspicious, doesn't it?

Remember what happened at Roswell?

After first saying they had captured an alien ship,

the military then changed their tune,

denied everything,

and the conspiracy theorists have reveled in it ever since.

I'm getting paranoid here.

Are you paranoid,

or is it just me?

Why are you looking at me?

Why are you looking at me?

This is military communications expert Steve Douglass.

He believes the Stephenville lights

were indeed Air Force flares,

but they were being used as part of a military cover-up,

not to hide the existence of aliens

but something far scarier --

to hide top-secret black ops.

Whoa.

Steven Douglass: Well, as it goes with the Stephenville sightings,

I think the truth is that a lot of people were seeing

what they think are extraterrestrial spaceships.

They're not.

They're seeing military projects.

I'm basically what you would call

a black project researcher.

I'm one of those guys who gets in a lawn chair

and sits out on a mountaintop,

looking over a base that doesn't exist,

hoping to see the odd secret spacecraft, airplane,

whatever new widget the military is using.

William Shatner: One of these "secret widgets"

currently flies over Afghanistan --

the RQ-170 Sentinel,

otherwise known as "The Beast of Kandahar."

Steven Douglass: Because of guys sighting it and taking pictures of it,

the Air Force came clean and said,

"Yes, we have this thing flying,

and it's a surveillance platform."

William Shatner: A stealth drone with no metal parts,

completely undetectable by enemy radar

that's entire existence was denied by the U.S. military

until December 2009 --

scary but cool.

Just this year alone,

the new military budget is at $108 billion

with 44 billion of it

earmarked for covert operations alone.

William Shatner: Douglass also believes

the Air Force may have another still top secret

piece of surveillance hardware cruising high in the skies,

not over a far away combat theater

but right here,

right now, over the United States.

We call it the stealth blimp,

and it flies at very high altitude --

200,000' or 300,000'.

You don't know it's up there,

and it can do everything from listen to look to see.

It's the ultimate flying Big Brother,

is what a stealth blimp could be.

You know, there could be one listening to us right now.

William Shatner: According to Douglass,

it was a malfunctioning stealth blimp

that was to blame for what happened

in the skies above Stephenville on January 8, 2008.

Well, as it goes with the Stephenville sightings,

I think it was a combination of two events.

I think it was some type of covert black projects operation,

maybe, like, one of these stealth blimps

was forced down in altitude.

Because of it happening,

which I think was just a happenstance,

the military put on what I call a dog and pony show,

which means they threw a bunch of fighters in the area,

dropped some flares, made some lights,

asking you to kind of look over here

but not at that thing over there.

William Shatner: So, were the mysterious lights over Stephenville that night

simple flares used to distract attention

from a black op gone wrong?

Or were the flares being used in a routine exercise?

Or were the good people of Erath County,

like Steve Allen

and the police officer, Lee Roy Gaitan,

right all along?

Could the origins of the Stephenville lights

be from another world?

Perhaps, but for now, the mystery remains

weird, or what?

Northern California.

The Coast Guard launches a desperate search

for a fishing boat

that has mysteriously vanished without a trace.

They find nothing.

It's the third unexplained disappearance

on this stretch of coastline in less than a year.

Does America's Pacific Seaboard

have a new Bermuda Triangle?

It's time to uncover the truth.

.

Old mariners' tales of the perilous ocean

swallowing ships and whole crews are legend.

But in the 21st century,

when several vessels fitted with high-tech communication systems

vanish without a trace

on the same stretch of American coastline,

is that just weird, or what?

September 20th, 2004.

Humboldt Bay, California.

Here, one of the main employers is commercial fishing,

an industry that ranks among the U.S.'s deadliest professions

with a fatality rate five times higher

than that of police officers or firefighters.

A 46' fishing vessel, called the Marian Ann,

crewed by Bill Burchell,

John Mogg and Maurice Alvarado,

sets off on a routine three-day fishing trip.

Their first stop is scheduled for Eureka, California,

the following morning, just a few miles up the coast.

But the Marian Ann...

never arrives.

Jennifer Mogg: They were expected in to deliver fish at 6:00,

September 21, in the morning.

Suzie Howser: I showed up there, and the boat wasn't there.

They were never late, ever, ever, ever, ever.

I instantly started freaking out.

It's pretty rare

for a commercial fishing boat to be reported overdue.

William Shatner: Fearing the worst, the Coast Guard,

commanded by search-and-rescue controller Jim Egbert,

springs into action.

Coast Guard, Humboldt Bay.

What is your emergency?

We issued an urgent marine information broadcast,

asking for information,

to see if anybody's seen them, heard from them.

William Shatner: But no one has.

Time 6:30 a.m., local.

The Coast Guard issued a report of fishing vessel Marian Ann --

40' fishing vessel overdue on a voyage from Eureka.

All vessels in the area

are requested to keep a sharp lookout,

assist if possible

and report any sign of distress to the Coast Guard.

William Shatner: Puzzled by the mysterious fact the crew of the Marian Ann

had not sent a distress signal, the Coast Guard heads

straight to the boat's last known location.

Man: This is the United States Coast Guard,

Humboldt Bay, California.

Jim Egbert: Usually, there's some kind of, you know,

a call from the boat, an activation of EPIRB.

The boat carried a NOAA vessel monitoring system transponder

and was able to find the last position

where they had stopped transmitting.

William Shatner: The last time the boat logged its position

was at 7:22 p.m.,

just 20 miles off the coast.

Jim Egbert: My level of apprehension was pretty high,

so we went right to searching for them immediately.

William Shatner: But what they do find

offers little hope of finding them alive.

Jennifer Mogg: They found the life raft

and a couple of buoys

and an ice chest.

But unfortunately weren't able to find the vessel

or any of the survivors

or the crew members.

William Shatner: After two days, the search is called off.

The Marian Ann and its crew have vanished,

seemingly into thin air, just weeks after one crewmember,

Maurice Alvarado,

has told his mother it was time

to leave his dangerous job behind.

Phyllis Sovereign: He says, "You know, mom,

I think it's time that I get off the boat."

I said, "Why?" and he says,

"Well, I need to spend more time with my children."

And, like, three weeks later, he was gone.

There's just no way to explain.

You just can't believe that they're not coming home.

So, what could have caused the Marian Ann,

a 46' boat, to vanish in normal weather

so quickly the crew didn't have time

to send a distress signal?

For San Francisco Coast Guard

senior investigator Ross Wheatley,

the disappearance of the Marian Ann

is the latest incident in a much bigger mystery.

There is more to the story, in this particular case,

because this was the third vessel sinking

in a relatively short period of time.

June 21st, 2004.

The Relentless, a 50' fishing trawler,

vanishes with all hands.

Also in 2004, the Gina Lisa went missing.

It was later found in 4,000 feet of water,

sitting upright at the bottom of the ocean.

Like the Marian Ann,

both cases were off the California coast.

The weather was fine.

No distress signals were sent.

Something weird...

is happening on the coastline of Northern California,

but what?

Here at the Stevens Institute,

the Center for Maritime Systems in New Jersey,

Dr. Alan Blumberg and his team of researchers

are looking for an explanation.

This facility tests marine hydrodynamic properties in boats

using two large water tanks.

Today, they are going to test an incredible theory,

a destructive phenomena

long thought to be a mariner's myth --

rogue waves.

A rogue wave typically would be characterized

as an unusual wave of very large amplitude --

for example, 100' high --

and they cause a lot of damage when they impact your vessel.

William Shatner: Rogue waves are thought to occur

when fast currents and strong winds

focus smaller waves together

into one big, devastating wall of water.

In the lab,

the team has made a model to simulate the Marian Ann.

Mike Morabito: We're gonna put this model out in the tank,

and we're gonna run some large waves at it.

William Shatner: Using a sophisticated wave-making machine,

they are attempting to simulate

the conditions created by giant rogue waves.

Mike Morabito: Well, we're basically testing what would happen

if a large rogue wave came up on this vessel.

William Shatner: The results are simple and dramatic.

It takes only a few waves

to overwhelm the model.

Mike Morabito: When you see it sinking,

you see what that time scale is gonna be.

It's gonna be pretty quick.

William Shatner: If surprised by a rogue wave,

the Marian Ann could have sunk in seconds

with no time to send a distress signal.

It seems a plausible theory,

but without finding the boat, it's impossible to prove.

But refusing to give up,

the Coast Guard are about to make an astonishing discovery.

.

William Shatner: A fishing trawler has vanished

off the coast of Northern California.

After a search yields nothing,

the Coast Guard asks the US military for help.

Ross Wheatley: The Coast Guard contacted the Navy.

They came up and conducted

what they call a side scan sonar search of the bottom

in the general area in which

the fishing vessel was believed to have sank.

They developed, basically, a 20 square mile box,

in which they forecasted

that the vessel most likely would sink if it actually sank

at the time that they stopped broadcasting.

They searched that 20-mile square box

for basically three days.

William Shatner: After an exhausting sonar search,

the boat is finally found,

2100' underwater.

Equipped with an underwater camera,

the Navy sends down the submersible,

and what they discover

is shocking.

The ship is perfectly intact,

with no signs of damage.

Ross Wheatley: The vessel is sitting upright on the bottom.

There's no clear indication of any type of a collision.

Unfortunately, after viewing the video,

it basically didn't help us determine the actual cause

of what's caused the vessel to sink.

William Shatner: This disturbing discovery creates

more questions than answers.

What could be powerful enough

to sink a ship in seconds

yet leave no damage?

To solve this mystery,

investigators need more clues.

They go back to the video.

Upon closer examination, it is revealed

that the Marian Ann's nets were almost fully retracted.

Ross Wheatley: We were able to locate the fishing net.

It's, for the most part, hauled up on the wheel.

William Shatner: Investigators theorize that because the nets were up,

the boat was loaded with fish

and may have become unstable.

Ross Wheatley: One of the issues that we've seen in other vessels,

or other casualties,

is sometimes the question of whether or not

the product onboard,

if it's not properly segregated,

can shift as the vessel deals with the weather

and that can cause stability issues.

William Shatner: To keep a boat stable,

distributing the catch evenly in the cargo hold is vital.

Unbalanced, a vessel can roll too far

and rapidly take on water.

If this happened to the Marian Ann,

it might explain why no distress signal was sent

and why there was little visible damage to the ship.

Investigators closely examine the video

to see if this was the reason why the boat sunk.

In this particular case,

we weren't able to see inside the fish hold,

so we couldn't make any type of determination.

William Shatner: Due to the extreme depth,

the divers are unable to examine the inside of the boat.

The investigation hits another dead end.

But now a bizarre new theory has emerged.

Could the Marian Ann have been sunk by volatile,

highly destructive methane gas bubbles?

In 1985, a cameraman captured

extraordinary footage of a drilling platform

in the North Sea being destabilized

by methane gas bubbles from the ocean floor.

Dr. David Vaccari believes

this could also have theoretically

overwhelmed the Marian Ann.

Methane is formed in the sediments

by biological processes.

Bacteria, in the absence of oxygen,

will undergo a fermentation process

and produce the methane.

William Shatner: Methane hydrates are found in oceans all over the world,

buried beneath the ocean floor.

They release methane bubbles when exposed to warming seas

or underwater earthquakes.

If a swarm of small bubbles rose under the ship,

it would decrease the density of the water

the ship was floating in.

The ship would then settle down into the water,

possibly enough to cause it to swamp

by water coming over the side of the ship directly.

William Shatner: To test this theory, researchers placed a boat

in the water and laid a system of pipes

on the seabed beneath it.

Air pumped through the pipes simulates methane gas,

creating thousands of bubbles

that float to the surface with dramatic results.

David Vaccari: It's possible for bubbles to sink a ship.

Is it likely?

That, I would need more evidence to support the likelihood.

Despite six years of investigation,

theories and speculation,

the definitive cause of the Marian Ann's tragic sinking

has yet to be resolved.

With no answer in sight,

the US Coast Guard has finally closed the case,

saying the boat sank from causes unknown.

But in Humboldt Bay,

the boat and its crew have not been forgotten.

Jennifer Mogg: It's not that distant.

It's still very new and fresh

and still a very big mystery

and, um, no closure.

Still have no idea what happened.

William Shatner: So, for now, this is one mystery

that cannot be explained.

Boats are sinking, and nobody knows why.

Is that weird, or what?

So, there we have it --

three strange and mysterious stories

but each with many plausible theories to explain them.

What did the good people of Stephenville, Texas,

see in the skies that night?

Were the mysterious lights really military flares

dropped from fighter jets,

or were they spacecraft from another world?

Why did the Marian Ann

end up at the bottom of the Pacific Ocean?

Was it overwhelmed by a rogue wave?

Was it sunk by methane bubbles?

And what could explain the spooky and mysterious sound

that rose from the depths of the Pacific Ocean?

Was it an earthquake?

A volcano?

Was it man-made, or do huge,

unseen creatures lurk in the deep?

Join me next time for three more stories

that will undoubtedly be...

weird, or what?