Original subtitles

[Josh] Welcome to the Indian Ocean.

I'm sailing off the coast of Tanzania

here in East Africa.

The trade winds are blowing strong.

Perfect weather for me

to begin my search for a sunken city.

But when it comes to legendary lost locations,

there is one name that stands above all others.

Atlantis.

It is synonymous with mystery,

a utopian island,

an advanced naval power,

not to mention a killer resort in The Bahamas.

Atlantis started as an allegory

by the Greek philosopher Plato in 360 BC.

The island kingdom tries to take down Athens,

an act of hubris which annoyed the gods enough

to send them crashing to the bottom of the sea.

It is a fascinating fiction that's been

retold for centuries

and earned a billion at the box office.

But it turns out there are real life lost cities

hiding beneath the waves.

And I should know.

I've gone looking for them.

My own longstanding fascination with these tales has

taken me beneath the waves all over the world.

From India's legendary sunken city of Dwarka

to waterlogged structures

in a high altitude lake in the Andes.

I've investigated the enigmatic

Yonaguni ruins in Japan.

And even the dubiously titled

Bimini Road in The Bahamas.

And now I'm on a quest

for another Atlantis.

What, Aquaman gets a sequel, why can't I?

Especially considering

this is a city like no other.

It is a very real

and very lost ancient emporium.

The Roman Empire's southernmost trading outpost,

known as Rhapta.

Several thousand years ago,

Rhapta was a major center of maritime commerce.

Through its port flowed the treasures of Africa.

Gold and silver, ivory, tortoise shell

and priceless jewels.

It was a place rich in ceramics.

Both ornate vessels and large storage jars

which were traded to and from

the bustling seaside city.

By the Middle Ages, though, it's gone.

All traces of this metropolis and its precious goods

vanish from the face of the earth.

But now, new efforts are underway

to reveal its true location.

It is believed that a powerful tsunami

may have destroyed Rhapta.

But now, new clues are coming to the surface.

One archaeologist is exploring

a graveyard of shipwrecks

that may point to the long lost site.

Meanwhile, a different team

thinks they've discovered

submerged harbor walls

that once surrounded the mighty outpost.

Finding Rhapta would rewrite maps

of the Roman Empire.

And could lead to knowledge and artifacts

beyond our wildest dreams.

So let's trim the sails

and set a course

for Africa's Atlantis.

[theme music playing]

[Josh] The past is all around us.

Oh, this is crazy.

A world of mystery.

-This is a plane. -[man] Yeah.

[laughs]

Danger.

We are about to be underwater.

Whoa!

And adventure.

It's just straight down!

[exclaiming]

I travel to the far corners of the earth

to uncover where legends end...

[screams, laughs]

...and history begins.

Okay, let's punch it.

I'm Josh Gates.

And this is

Expedition Unknown.

My search for Rhapta begins

on another historic African outpost.

On the island of Zanzibar.

It's been on maps for as long as maps have been drawn.

And at its heart is Stone Town.

It's a weathered labyrinth of

moldering citadels and narrow streets.

All covered by a blanket of rusted tin.

Everything here feels exotic,

right down to the ornately carved wooden doors.

It's not every day you encounter brass spikes

to defend against ramming elephants.

On these humid streets, you rub shoulders

with an eclectic crowd.

From Muslim traders and Buddhist monks

to Maasai warriors and some high-flying kids.

I'm on my way to meet a local explorer

with new information about the hunt for Rhapta.

But in this neighborhood,

it's a good idea to leave a little early.

-I'm good, brother. All right? -Boom.

Good, yeah.

Stone Town is a place like no other.

I could pick up a local street map

but frankly it wouldn't help.

Getting lost here is all but guaranteed.

And, well, kind of the point.

They say all roads lead to Rome.

But in Stone Town, they converge at

a coffee and dominoes hangout known as Jaws Corner.

I wonder why they call it that.

I'm gonna need a bigger cup.

Maybe it has something to do with the sharks

circling the domino tables.

Yeah I'm ready.

-I was the president of my high school dominoes club. -Really?

Oh, no, wait a minute, I worked at Domino's.

-[man laughs] -It's close.

-Okay, here we go. Come on. Bring it. -[man] Okay. Double draw.

-[mouthing] I have no idea what I'm doing. -[man] Two.

Two, eh?

Hit. Double four.

-Double four. -[man] Go.

[Josh exclaims]

Six.

-Yeah. Yeah! -Okay.

Here we go.

Again. Again. Again. Again.

-[people cheering] -Yeah!

Give me the watch. Come on.

No.

[Josh] I may be flush with victory,

but Rhapta awaits.

To hear the story of this once-mighty city,

I head to the rooftop bar of the exotic Emerson Hotel.

This one-time palace boasts the best views

of Zanzibar in town.

Up many flights of stairs,

I find diver and explorer, Alan Sutton.

[Alan speaking foreign language]

-[in English] Take a seat. -[Josh] Thank you.

Alan has lived and dived in Zanzibar for decades,

and nobody knows more about the island's history

and legends.

This is incredible.

-[Alan] This is paradise. -It is paradise.

The only thing missing from our view here is Rhapta.

Yeah. Um,

Rhapta's been missing for a long, long time.

-Very long time. -[Alan] Yeah.

So, okay, help me understand this place.

When do we first hear about Rhapta?

When is it first written down?

Well, about 2,000 years ago, from a periplus.

A periplus. I'm gonna need some help with that.

Yeah, well, a periplus is a nautical log.

[Josh] Specifically, a periplus

is a record kept by sailors

to note landmarks and harbors

as they navigate through unfamiliar areas.

And Alan's research has revealed this one

from 40 AD,

when an unnamed Roman merchant

sailing the ports along the eastern coast of Africa

recorded a detailed account of his trip.

Okay, to get my bearings here, we have

India and Arabia and this is eastern Africa.

-[Alan] Eastern Africa. Yeah. -[Josh] Okay.

And if you look over here,

you'll see...

[Josh] "Rapta Emporium."

-[Alan] Yeah, that's correct. -It's on the map.

Yes, it is.

[Josh] Translating the periplus,

we learned that Rhapta

was the very last trading outpost for Rome

on the African continent.

And the description is that this is

kind of a happening place.

Yeah, it must have been bustling.

You know, they're dealing with really high-end products.

[Josh] In the first century, the Roman Empire

was home to more than 50 million people,

a quarter of the world's population,

many clamoring for exotic goods from Africa.

And Rhapta had it all.

Lucky for us,

the periplus gives up an amazing clue as to

where this emporium was.

It says the city was two days' sail

south of an island known as...

[Alan] Menouthias.

-Menouthias. -[Alan] Mm.

And what do we think Menouthias is?

[Alan] Well, Menouthias is, uh,

Zanzibar, which is right where we are now.

-[Josh] So we're in Menouthias? -[Alan] Yes.

[Josh] Based on a projection

of how far a ship could sail in two days' time,

Rhapta must lie within a search zone

of a few hundred miles from here.

Okay, so we have some good clues here now.

We know it's off the coast of East Africa.

We know it's within a few days' sailing of where we're sitting.

-So we're close? -Yeah, we're definitely close.

Can we get closer?

-Yeah, we can. -Okay.

In AD 150,

uh, Claudius Ptolemy mentions Rhapta as well.

-Okay. -And we can have a look at his map.

Okay.

We trade in one ancient map

that Alan's uncovered for another.

I have to say, for being 2,000 years old,

this map's pretty incredible.

-We have a real sense of the shape of Africa here. -[Alan] Africa.

If you have a look over here...

-Oh, right there. -Yeah.

-[Josh] Rhapta. -[Alan] Yes.

And you'll see it calls it a metropolis.

-A metropolis? -Yes. It's expanded.

[Josh] Ptolemy's account, written only 100 years

after the periplus,

describes the city as being much more significant,

including fortifications

and a sizeable harbor,

which would have been necessary

to accommodate Roman ships

of up to 150 feet in length.

Well, Alan, now I'm confused.

We've got two different maps here that show Rhapta.

It's two days' sail from here.

Why can't we just go there?

Rhapta vanished.

-Literally? -[Alan] Literally.

By the Middle Ages, it's disappeared. It's gone.

No one knows where it is.

[Josh] The legends say that Rhapta,

like Plato's storied city,

was swallowed by the ocean,

perhaps obliterated by a violent tsunami.

But, of course, Plato's Atlantis is

the stuff of legend, but this is real.

Look, there's no question this was a real place,

and it's gone.

So, Africa's Atlantis?

Africa's Atlantis, yes, correct.

[Josh] And by studying these maps and documents,

there's one place within the search zone

that Alan has pinpointed

as concealing this real Atlantis.

Most people think that it's under the ocean

and, uh,

close to Mafia Island.

Mafia Island?

So it's in Italy?

No, it's not. [laughs] In Swahili, Mafia means

a pleasant place to live.

Thought it meant sleeps with fishes.

-Different Mafia, yeah. -[Josh] Okay.

Mafia Island is about how far from here?

It's two days' sail south of here.

Okay, that's good.

And in Ptolemy's account, uh,

he describes Rhapta as being at seven degrees south.

And interestingly,

Mafia Island is at seven degrees south.

[Josh] In other words, a perfect candidate.

Do we know exactly where off the coast of the island

Rhapta might have been?

We don't know exactly where it is yet.

But there are two groups of archaeologists on the island

looking for it.

And I can introduce you to them.

-I would love that. Okay. -Great.

To Mafia.

I'm heading to an island off the coast of an island

known as Mafia.

But a two-day sail is not in the cards.

So I squeeze aboard a Cessna 208 Caravan.

It's a tight fit.

[exhales]

All right, well, what else do we need?

Oh, right.

Once the crew boards, we take off

and I settle in for a quick 100-mile trip.

It doesn't take long to spot our destination.

There's the island.

[Josh] Wow.

Mafia may be six times the size of Manhattan,

but only has 3% of its population.

We land at their version of JFK.

Okay.

Now what?

Alan called ahead to the archaeology team here

to say I was coming.

But there's no cab to hail.

Instead, I just grab one of these.

Well, this little three-wheeled beauty is known as a tuk-tuk.

At least that's what they call them in Thailand.

Around the world, they're known as pigeons,

jonnybees, bajaj,

bao-bao, or easy bikes.

Hey, what do you call this?

It is a tuk-tuk.

It's a tuk-tuk.

Yeah. It's a tuk-tuk.

As to why it's emblazoned

with a huge sticker that reads "Boss Lady" that's

partially obscuring my view,

it's because I insisted they put it there.

What can I say? I'm a sassy CEO.

Let's do this.

The team I'm meeting is across the island,

so I've got a bit of a drive.

Just look at this island.

Mafia is one of those places you just

don't find in the world very much anymore.

There's a little bit of tourism here.

But at one point, this may have been

a bustling emporium

where the treasures of the continent

were traded with the Roman Empire.

I make my way to the far side of the island

where I trade in three wheels for no wheels,

and motor well offshore

to a set of watery coordinates.

There should be absolutely nothing here,

which is why I'm puzzled to spot...

land?

Whoa.

What is that?

[Josh] Whoa.

What is that?

On remote Mafia Island off the coast of Tanzania,

I'm searching for the lost city of Atlantis.

No, not that one.

I'm talking about Rhapta,

known as the Atlantis of Africa.

Once a wealthy center of commerce

thousands of years ago,

it vanished beneath the waves of the Indian Ocean.

Or did it?

That's land.

Not much, but it's land.

I transfer to a waiting skiff

and complete my journey to this

improbable spit of terra firma

where I find archaeologist Caesar Bita

and Dr. Felix Chami.

Professor Chami, I presume.

-Yeah. Welcome. -[Josh] Thank you.

Very nice to meet both of you.

Now, I have read that you are the world's

foremost authority on Rhapta.

It is true, yes, yes.

Does that mean that you know where Rhapta is?

Yes, I know exactly where it is.

It is under your feet.

-[chuckles] -This is Rhapta?

Yes, the metropolis of Rhapta.

[Josh] We are standing on a mysterious linear formation

that rises up out of the Indian Ocean.

The locals have long referred to it

as Mwamba Ukuta,

or the Rocky Wall.

You are standing now on the wall of Rhapta.

And it's quite long,

three miles east-west.

You can see how extensive it goes.

[Josh] So this whole thing I see going off into the distance,

-that's all part of Rhapta? -[Caesar] That's it.

You say this is man-made?

Yes, this is man-made, exactly.

[Josh] But to my eyes,

it is not at all clear that this is man-made.

It's the kind of hotly debated question

I've encountered before.

Have you ever heard of the Yonaguni ruins

-in Japan? -Yep, yep, yep.

This is another place that

there's a real debate

as to whether it's man-made or geological.

[Josh speaking]

And this site is just as puzzling.

Is this the work of human engineering?

Finding out won't be easy.

I'm informed that Mwamba Ukuta here

only shows itself for a brief period every day.

So as the tide comes up, this gets submerged?

Yeah, it gets completely submerged.

How much time do we have?

[Caesar] Hmm.

Roughly

-half an hour to one hour. -[Josh] Half an hour?

-And then we're underwater? -[Caesar] We will be submerged.

[Josh] Suddenly, we're on a short clock

to examine the site

before the sea claims it once again.

So do you have any doubt that this is Rhapta?

Not at all.

Prove it.

Okay, let us go. I'll show you boulders.

Please, show me the boulders.

Since Rhapta was likely destroyed by a tsunami,

Dr. Chami contends that

this toppled wall is what's left.

We walk down a rapidly sinking path

atop the formation

to see his proof

lying half submerged in the water.

Look at this!

This looks like a block.

Oh, my word,

that is like a squared-off block.

[Caesar speaking]

[Josh] This is crazy!

[Caesar speaking]

[Josh] I mean, they are rectangular blocks.

This looks like a LEGO set.

[Caesar speaking]

[Josh] Let's see.

Okay, so I'm putting this right up in the corner.

[Caesar speaking]

78 inches. So more than 6 feet.

So what do you think this is?

Is this carved stone

or is this like concrete?

This is what we call Roman concrete.

Roman concrete.

The ancient Romans were masters of engineering

who invented so-called hydraulic concrete,

which was used to build harbor walls

across the ancient world

by sinking squared-off caissons of cement

that set into a rock-hard material.

Dr. Chami and Caesar

have recorded these types of so-called blocks

all along the vast extent of the wall.

They also contend that there are clear

architectural blocks underwater,

as well as possible remains of pottery or artifacts

from Rhapta's rich emporium.

Can we see it?

We can see it.

We can dive and see it.

[Josh] Okay, we're running out of dry land here.

Okay, let's get moving. This tide is coming in real quick now.

In the few minutes we've been here,

the waves have gotten higher,

and the land beneath our feet

is rapidly disappearing.

We're about to get swamped.

This tide is really coming in now.

Oh, big wave! Caesar! Caesar! Come here!

We climb what passes for higher ground here,

and we call in a boat

to pluck us out of the rising water.

-Hey! -[Chami] Bring the vessel here!

[Josh] Hang on, hang on!

Okay. Let's get aboard.

We make it aboard safely

and watch as the mysterious stone structure

retreats beneath the waves.

That wall, if it is a wall,

would be a huge discovery,

and could put Rhapta back on the map.

But not without a smoking gun.

It will take unimpeachable signs

of human construction,

or the discovery of Rhapta's ancient artifacts,

to prove this is the missing emporium.

The truth is underwater,

which is where we intend to go.

[Josh speaking]

[Caesar speaking]

[Josh speaking]

Our time here is limited.

Once the tide fully sweeps over the wall,

the strong current will sweep us out to sea.

We'll need to work fast.

[Caesar speaking]

[Josh speaking]

[Caesar speaking]

[Josh speaking]

[Caesar speaking]

[Josh speaking]

[Caesar speaking]

[Josh speaking]

The Romans' engineering prowess

extended to water management.

They built elegant aqueducts that function to this day.

Caesar thinks this channel

could be part of a system that they built for Rhapta.

[Caesar speaking]

[Josh] It may look that way,

but looks have been known to deceive.

We continue to search the bottom for any artifacts

or evidence of construction.

It's a job made more challenging

by the strong current,

which drags us against the reef.

But this is the only way we're going to find

conclusive evidence of Rhapta.

[Josh speaking]

[Josh speaking]

[Caesar speaking]

[Josh] I'm diving on an enigmatic rock formation

that may have once served as an outer wall

for the lost trading metropolis of Rhapta.

We don't have much time before the strong current overpowers us.

And we've just discovered blocks

that appear to have signs of being manufactured.

[Josh speaking]

[Caesar speaking]

[Josh] We take measurements to see how this block

compares to the one we examined on the surface.

[Caesar speaking]

[Josh speaking]

[Caesar speaking]

[Josh speaking]

Admittedly, the blocks here are compelling.

But as we sweep the sand, we don't see any pottery fragments,

anchors or other telltale remains of a port.

And soon, we can't see anything at all.

[Caesar speaking]

[Josh speaking]

Professor Chami is a true believer.

To him, these are the Walls of Rhapta.

He doesn't need to see more proof, but I think I do.

Rock formations can fracture along perfectly straight lines,

and until the blocks can be cored and studied,

I'd say it's much more likely

that this is a natural barrier reef.

But fear not,

because right now, there's another group of explorers on Mafia Island,

also on the hunt for Africa's Atlantis.

So I navigate back down the coast,

and come ashore at a place called Chole Bay.

It's here that I meet Bridget Buxton,

a professor at the University of Rhode Island

with a PhD in ancient history from UC Berkeley.

Her work as an underwater archaeologist

has taken her from the Black Sea to New Zealand.

Joining her, is pottery expert and field archaeologist,

Professor Alexandra Ratzlaff.

-Hi, I'm Josh. -[Bridget chuckles]

-Nice to meet you. -Great to meet you.

-Hi. Alex. -Alex. A pleasure.

I come seeking Rhapta.

You have come to the right place.

Sort of. [chuckles]

Okay, wait. So, have I? I mean, do you think

Rhapta was somewhere around Mafia Island?

-Yes. -[Josh] Okay, that's good. I'm not on the wrong island.

Now the question is, where?

That's the better question. Where is it?

Where does the evidence point us?

So I have just been to one potential candidate for Rhapta,

this place Mwamba Ukutu.

Are you bullish on that as Rhapta?

Sorry, no, that is not Rhapta.

I have seen many formations like that

with more than 20 years of working underwater.

With Mwamba Ukutu, it's not about what's there, it's about what's missing.

If it was this major Roman city or emporium

and this trade nexus,

you would have monumental architecture,

you would have domestic houses.

The Romans weren't shy about leaving their footprint.

If they decided to show up somewhere, you'd know about it.

And even this argument that a tsunami

may have swept through and destroyed the city...

If this is the Amazon fulfillment center of the ancient world,

-where are all those boxes, right? -[Alexandra] Yeah.

Which is the pottery in this case.

Yeah, we're missing all the shipping containers.

So that leads to an obvious next question.

Where else do we look, and how do we look?

We look in the sea, and we look for shipwrecks.

One of the places that ships love to have accidents

is close to a port.

Shipwrecks equal port, port may equal Rhapta.

That all makes good sense.

So, how do we find those shipwrecks?

The number one way to find shipwrecks...

ask the local people.

The local people have been reporting

a lot of interesting sites, just out here.

What are the items that we want to find to say we are in Rhapta?

I'd love to find anchors, because we know from Roman texts

that Mediterranean style, Roman style ships

-were trading in this ocean. -[Josh] Right.

[Bridget] But no one's ever found one of those ships.

I'd love to find pottery.

This is an area of expertise for you, right?

-[Alexandra] Absolutely. -You are a pot-head.

-[Alexandra chuckles] -Is that-- Pot expert. Pottery expert?

-Did I use it correctly? -I don't think that'd be a stretch.

Okay. Perfect.

Yeah. So, the pottery I look at

tells me, not only about what the Romans have,

but what the Romans that came to Mafia,

that came to Rhapta, brought with them.

Okay, so we know what we're looking for.

Now we just need to find it.

Should we go diving?

-Sounds good. -Let's do it. Come on.

We get back on the boat

and head out to the coordinates

provided by local fishermen,

where they think they've found evidence of shipwrecks.

Bridget and I prepare to dive the coordinates,

while Alexandra will stay topside.

[Bridget speaking]

[Josh speaking]

The conditions here are better than at Mwamba Ukutu,

at least for now.

While currents here can also be treacherous,

at least I can actually see my hand in front of my face.

[Bridget speaking]

[Josh speaking]

[Bridget speaking]

[Josh speaking]

[Bridget speaking]

[Josh speaking]

[Bridget speaking]

We continue to search for signs of a shipwreck,

suddenly mindful of Bridget's suggestion to search carefully.

[Bridget speaking]

[Josh speaking]

[Bridget speaking]

[Josh speaking]

Moray eels aren't venomous,

but their jaws and teeth are powerful,

with bites prone to infections.

I'm so busy looking down,

I fail to notice the shadow overhead.

[Bridget speaking]

[Josh speaking]

Whale sharks are the largest fish in the ocean,

growing up to 60 feet long.

They're gentle giants,

gliding through the waves and dwarfing us in their wake.

With the whale shark swimming away,

we refocus on the mission.

[Bridget speaking]

[Josh speaking]

Fighting the currents as we scour the seabed,

something catches Bridget's eyes.

[Bridget speaking]

[Josh speaking]

[Josh speaking]

[Bridget speaking]

[Josh] In the Indian Ocean,

I'm looking for evidence of Africa's Atlantis,

the very real sunken port city of Rhapta,

which was once the southernmost Roman trade center

on the continent.

We've just discovered a collection of ceramic vessels,

and resting beside them...

[Bridget speaking]

[Josh] Ballast stones were once used

to steady the hulls of ships,

weighing them down in the water so they wouldn't tip over.

If this ship was made of wood,

it's possible these stones could be the only thing

to survive centuries underwater.

So we likely have a shipwreck.

Finding out if it's from Rhapta, though,

will mean identifying its cargo.

[Bridget speaking]

[Josh] Before attempting to raise one of the pots,

we have to carefully select one strong enough to survive the trip.

[Bridget speaking]

[Josh speaking]

From topside, Alexandra sends down a recovery basket

to cradle and raise our find.

[Bridget speaking]

[Josh speaking]

[Bridget speaking]

[Josh speaking]

Safely loaded,

we bring the artifact to the surface,

until, at long last,

this piece of pottery sees the light of day

for what may be the first time in centuries.

[Alexandra] Oh, wow.

It's a complete vessel.

-Whoo! -[Alexandra] I'll get this.

-[Bridget] All right, let's try to get it out. -[Josh] Careful, careful!

-Up we go. -[Alexandra] We're done.

-Careful. -[Josh whoops]

This is amazing. We never find complete vessels like this.

I'm always working with shards that are the size of a quarter.

You guys have a full vessel here.

-It's really beautiful. -[Alexandra] Yeah.

[Josh] I mean, it is just almost complete.

Now, you are the queen of pottery here, as I understand it.

So if you had to date this, what would you say?

I would say that this is definitely post medieval.

So not old enough. Not the smoking gun of Rhapta.

Not Rhapta,

but the site was obviously important throughout history.

At the very least, it does indicate

that we may be in the right area.

-Any evidence is good evidence. -[Josh] All right.

You guys had an amazing find today.

Great work.

Reports of shipwrecks here will continue to be examined,

as the history of this region seems laid out on the seabed.

But back on the boat, Bridget and Alexandra

remind me that when it comes to Rhapta,

regional is not what we're looking for.

We want a site that tells us about international trade.

The ancient texts tell us that Rhapta

is an international emporium, a metropolis.

We're looking for something on a bigger scale.

Yes. There's another site that we'd like to show you

that we think is another important piece of this puzzle.

Okay. Where is this place?

It's called Ras Kisimani.

Okay. And do I get to know what's at this place?

-[Bridget] No. -You're going to need to see it.

Okay.

We hit the throttle hard and raced the tide

to the place known as Ras Kisimani.

Several hours later, we arrive at the tip

of Mafia's westernmost peninsula,

and climb out into the shallows.

Another low tide, another walk through the water,

and on this particular beach, it pays to look down.

Is that pottery?

-Oh, nice find! -That's pottery. Look at that!

This is the base of a... of a storage container, yeah?

[Alexandra] Yeah, and the storage vessels, we like finding these,

because it says harbor, facilities, infrastructure.

So this is part of the puzzle that we're looking for.

And there's more of this here?

There's so much more of it here.

This is why we brought you here.

Show me. Yeah.

She doesn't need to show me. Everywhere I step...

More pottery here.

Everywhere I look...

And more here.

And here.

-It's everywhere. -[Bridget chuckles]

[Josh] ...pottery is laid out before me.

-What do you got? -Something a little different.

Fifteenth century Portuguese import.

And so, what is this doing here?

This is more indicative of a town, a city,

some permanent settlement.

[Josh] We wanted evidence of international trade,

and here we have it.

And the Middle Ages would be right around the time

Rhapta is said to have sunk into the ocean.

And along with the pottery,

there's other clues revealed by the low tide.

[Bridget] Guys, come and have a look at this.

-[Alexandra] Ooh. -[Josh] Find something?

[Bridget] Yep.

[Josh] What is this?

[Bridget] This is an anchor.

[Josh] This is an anchor!

[Bridget] Yep.

-[Josh] It's a stone anchor. -[Bridget] Yes.

[Josh] So we can see it has this squared off form,

and there's a hole through the center here for rope.

[Bridget] They were in continuous use

-for hundreds of years. -[Josh] Right.

Here we have now, literally, rock solid evidence.

that there must have been ships here.

[Alexandra] Where there's ships and anchors, there's a port.

[Josh] A historic ship's anchor and this much pottery

could be strong evidence of this as a trade center.

We quickly scan every inch of the beach.

Worked stone.

Pulling up clue...

That is a worked edge for sure.

This is man made here.

...after clue.

Whoa, loom weight!

[Alexandra] A loom weight?

-[Bridget] Yeah. -[Josh] That's super cool.

I'm seeing pottery with every step that I take.

Oh, sorry, just half a jar at my feet

while we're talking here.

This is insane.

And then, something green catches my eye.

-Bridget? -[Bridget] Yeah?

Bridget, come here!

It might be nothing, but it looks...

-[Bridget] Oh, my God. -[Josh] Is it?

-[Bridget] Yes. -[Josh] It is.

That is a coin?

Yeah. You found one.

[Josh] Get out of here!

[Alexandra] Wow, it's nestled right in between the pottery.

-You can see decoration. -Can you actually?

-Yeah, you can. -Oh, you can. There's writing on it.

But this is not a modern coin?

[Bridget] It's late in the medieval period if it's medieval.

-But that's old-- -[Josh] But it could be cleaned up for sure.

-Oh, yeah. -[Alexandra] Oh, yeah.

[Josh] We found trade goods,

and now, coins washing up on the beach.

This place has all the ingredients of a major marketplace.

But was it Rhapta?

We continue searching for proof.

Oh, my word.

Oh, my word! Look at this!

-[gasps] -That's not from here.

Look at this.

Bridget, come here!

[Alexandra] Bridget, this is something new.

[dramatic music playing]

[Josh] In Zanzibar's bustling night market,

amongst Swahili stews and seafood skewers,

I'm surprised to find a food I'm intimately familiar with.

Or at least I thought I was.

Okay, this is Zanzibar pizza?

Yeah, this is Zanzibar pizza.

Famous for its pizza.

Meat, we have vegetable,

we have nice cheese...

-Lobster? -Yeah, lobster pizza.

-Okay, I'm gonna have the lobster pizza. -One pizza?

One classic Zanzibar lobster pizza.

Just like Mom used to make.

Hakuna matata.

[Josh] Naturally, lobster pizza is made with two full cups of onions,

mayonnaise, an egg with the shell...

I'm sure they'll take that out.

...and presumably lobster?

All right, here we go. Moment of truth.

I got to say, it's great!

-Have you had pizza from America? -No.

-No? -No.

It's just like this. Nice work.

Yeah, hakuna matata.

Hakuna ma-tasty.

Is that stone?

It's stone. Really fine stone.

-Beautiful stone. -[Alexandra] Not local stone.

-Not even close. -[Josh] This looks like something

that would line a doorway.

On a remote beach off the coast of a Tanzanian island,

I'm exploring a treasure trove of ancient artifacts

from what I hope is Africa's sunken city of Rhapta.

And this one is jaw dropping.

This looks like an architectural element.

This is the nicest stone that we have seen.

This is about maybe a belief system or a cultural tradition.

This is going to tell us not just the fact someone was here,

-but who was here. -[Josh] Right.

[Alexandra] Beautiful.

That... That is incredible.

The low tide continues to reveal treasures,

many dating to around the eighth century,

when Rhapta vanished off the map.

Oh, hey, guys.

-[Josh] Got something? -Yeah. Check this out.

What do you have? More pottery?

[Alexandra] It's more pottery, but it's early.

This is probably a little juglet.

The bottom is worn out,

uh, and I'd push it into the Islamic period.

Maybe sixth century, which is pretty amazing.

Sixth century would put us within just a few centuries of Rhapta.

The earliest known pottery from this area

is the eighth century.

That's the absolute earliest.

Until a few seconds ago. Yeah.

Until a few seconds ago.

-We're turning back the clock here. -Definitely.

-Yeah. -[Josh] Let's keep turning it.

The objects buried on this beach

are snapshots from across cultures and centuries.

I'm absolutely stunned, especially by this.

[chuckles] I'm sorry, I keep picking up things that are really cool.

Is this of interest?

-[Bridget] It's Chinese. -[Josh] It is Chinese?

-[Bridget] Yes, it's Chinese. -[Alexandra] Yes, it actually is Chinese.

Look at that pattern.

It's beautiful.

This, so different than any other pottery that we've seen.

This is very, very finely made.

And then the glaze is just beautiful.

It covers the whole thing.

It is stunning.

But if this was the storied trading outpost,

where's the town itself?

The answer may be just up the beach.

Wow, what is this?

Is it a tower?

Tower foundations, yeah.

But something lopped the top off it.

I just noticed something. Look.

-[Josh] Shells. -You see what I'm seeing?

A layer of articulated shells.

-The killer just left its signature right here. -[Alexandra] Yeah.

[Josh] So when you see a line of shells like that, it says what?

Tsunami, big storm.

So, one of those waves that comes crashing in,

it pushes everything that way,

and then it has this trail of shells and marine life with it.

And it gets deposited,

and then all the heavy stuff on top of it

gets pulled back out to sea.

Well, there's a theory that Rhapta was destroyed by a tsunami,

and we might be looking at a tsunami fingerprint.

That is one of the biggest discoveries we have made here.

[Josh] This layer of shells is a monumental find.

It hints at a story, one of destruction,

perhaps of a thriving Roman trade emporium.

After all, literally at our feet,

we've just made a dizzying array of finds.

So, you're holding Chinese pottery,

we already picked up medieval pottery from Portugal.

Also, next to... contemporary African pottery from the medieval period.

And then we have going even further back,

possibly sixth century pottery.

And then, you throw in a decorative architectural element...

It doesn't get more diverse than that at a site.

[Josh] And stone anchors and structural elements, and a coin.

And all of those things share something else,

which is that they've all been destroyed.

There is some serious destruction happening here.

You have a major natural disaster.

Some kind of Atlantis scenario, yes.

Great. So, are we standing in Rhapta?

Maybe. We think this area here

is a good candidate for our missing city.

This whole coast, over the centuries,

has experienced catastrophes and huge erosion.

The ancient shoreline was much further out 2,000 years ago.

There could have been, maybe more city out there...

-Underwater. -...underwater.

This is just the beginning.

Thank you so much. I really appreciate it.

-All the best. -[Alexandra] Thank you.

-Thank you. -And thanks for finding so much stuff for us.

Of course. Are you kidding?

And for you to let me keep all of it, it's amazing.

[Alexandra chuckles]

[Josh] The story of Atlantis is one that has resonated across time

for more than 2,000 years.

It is a legend that pulls at our imagination.

But here, off the coast of East Africa

is a mystery far greater than Atlantis,

because it's entirely real.

We may be able to officially put Rhapta back on the map.

Because of these finds in just a few months,

an excavation will be launched

to study this speech in greater detail.

And based on the wrecks off shore

and the treasures at our feet,

I have a feeling that new discoveries here

will be nothing short of historic.