[SAM] My ancestors came from here.

They were taken from Africa in chains.

♪ During the slave trade more than 12,000,000 Africans were trafficked across the Atlantic to North and South America and the Caribbean.

♪ More than 2 million died en route.

♪ For 400 years, the traffic in Africans was an accepted part of life in the Western world.

How did people justify this?

♪ [people sobbing] The story of the slave trade is world history It's a world shame.

[KINGA] We're talking about going down 350 feet to the depths of the ocean.

You have to come to terms with it.

You have to confront it.

Diving and investigating sunken slave ships will reveal much about this overlooked history.

But to understand the broader picture behind the transatlantic slave trade, I'm enlisting the help of two award-winning investigative journalists.

[SIMCHA] Every part of the system encouraged abuse.

[AFUA] What happened to them and why?

♪ All of these Europeans thought that it was compatible to conduct this horrific trade, and at the same time these guys were going in to church and saying their prayers every day.

♪ Until that point, faith was everything.

[ANA] Yes.

Suddenly faith was not enough.

Now it was all about blood.

PROF NATHALIE: It would've been utterly terrifying and miserable.

There were diagrams which showed the most effective way to pack the largest number of captives into a given space.

♪ This is what it is, man's inhumanity to man and this is almost like the capital of it.

♪ [metal chain clicking] ♪ We've come to the English Channel to investigate a 350-year-old unidentified slave ship that scientists call "35F."

We're briefed by Dr.

Sean Kingsley, an expert on the wreck.

SEAN: The tragedy of site "35F" is this ship was wrecked within a day's sail of England at the very front door of the United Kingdom.

♪ Sometime between 1672 and 1685, "35F" sailed from England.

It was bound for West Africa.

The ship almost certainly set out from London, perhaps for modern Ghana, a five to 7-week journey.

It was owned by the Royal African Company.

At the time, the King of England, Charles the II, had a monopoly on the slave trade, and this was a company ship.

[waves and storm sounds] On its way back to England, the slave ship hit a storm and went down.

♪ "35F" was located by marine researchers in the early 2000s, photographed by robotic camera, and largely forgotten.

This particular ship is probably the earliest slaver in the world ever found.

And in this period, in the 1680s, the Royal Africa Company was importing around 5,000 slaves every year.

And we know that vessels like this had the capacity to carry 650 slaves.

If you look carefully and zoom in, you can see remains of these iron cannons and copper Manilla bracelets -- primitive currency that were used to barter with West Africa for elephants, gold and slaves.

All these types of material culture are typical of a ship that's going out to West Africa to participate in the slave trade.

So no one has put eyes on this wreck for 10 years now.

We don't know if it still even exists.

So your mission is to get out there, rediscover the site, and see what other bits of information you can extract to add to our story.

SACHA: Let's take a look at the charts.

Well, this is the Western approaches.

This is England.

Over here to the south is France.

Out where I'm standing is the Atlantic.

And the big motion of the sea, it's coming in here.

It's getting compressed between France and England.

The waves become higher, and the sea becomes more disturbed.

And that's why we've got around 5,700 shipwrecks around the British Isles.

And when there was a storm here, it was the "perfect storm".

To dive this, we need conditions to be good.

We need them to be calm, flat.

For all those factors to come together, it's just going to present a small window of opportunity.

♪ JOSH: So this is it.

It's not gonna be an easy one, as the wreck is about 45 miles away from land.

♪ We have the coordinates of the shipwreck site.

And to find it again, we'll be using one of the most advanced research vessels available.

♪ The local crew is very experienced, and they know how treacherous and unpredictable the waters can be.

[waves] ALANNAH: My dad is British, but my mom is Bahamian, descended from slaves that were brought over from Africa, so I'm straddling these two lives, these two ancestry lines.

This is probably the oldest slaver ever discovered, so with that information, I suddenly... my shoulders droop, and I feel this weight of responsibility.

♪ The story of the slave trade is world history.

England was involved in it.

Portugal was involved in it.

The French were involved in it.

The Dutch were involved in it.

The Africans were involved in it, right?

It's a world shame.

The world bears responsibility for it.

You have to come to terms with it.

You have to confront it.

[CREW MEMBER] One mile away from target.

♪ AFUA V/O: "35F" would have come to a fort like this one.

More than 30 of them dotted the coast of West Africa.

They were used as trading posts and dungeons, where Africans were collected and processed before being loaded onto slave ships.

♪ The Portuguese came first, but after that, almost every European power tried to get their hands on Elmina at one point, because it was a strategic location.

Right.

By the 1700s, the slave trade was the main business going on.

♪ So one of the things that most strikes me, Sam, about coming in here, is that building.

This part right here.

Yeah.

This square bit in the middle.

- Okay.

- That is a church.

♪ As this castle became a primary site for slave traders.

Is this the Protestant church or the Catholic church?

Well, initially it was a Catholic church.

Of course.

But when the British took it over, they continued to use it as a Protestant church.

All of these Europeans thought that it was compatible to conduct this absolutely horrific trade in the dungeons of this building.

And at the same time, these guys were going into church and saying their prayers every day.

♪ One of the things that I think is most upsetting is the kind of sexual abuse that happened here.

So in the Governor's bedroom, there's a trap door in the floor, and it leads through some ladders, directly down into the women's dungeon.

[fainted crying] ♪ One of them would be selected and brought straight up to the officer's bedroom.

Washed, because they were kept in a state of filth down there.

- Yeah, of course.

- And then he would rape her.

And he would just have free access to these women and girls.

I'm sure there were little boys who were subjected to the same.

Yeah.

♪ So it's a bit complicated for me when I come here.

I have Ghanaian family and I don't know if anyone who's related to me was actually trafficked in slavery, but I do know that my sixth great-grandfather lived here, not as an enslaved person, but as a slave trader.

He was Dutch.

He worked for the Dutch West India Company.

He came here to trade.

Reading not very deeply between the lines.

He would have been trading slaves.

And he had a child, as so many of the European men who came here did, with a local woman.

I don't know the circumstances of their relationship.

Could it have been consensual?

It's hard to imagine.

Doubt it.

I don't know anything about her.

So you got skin in the game.

- I've got skin in the game.

- Ahh... This place really means something to me.

♪ As it pulled into port, perhaps to Elmina, "35F" was carrying thousands of "Manillas", a currency invented by Europeans to trade in Africa for people, gold, and elephant tusks.

♪ Once they finished their business, they set sail for Caribbean slave markets.

To protect its valuable cargo from pirates, the ship was heavily armed with dozens of cannons.

[rattling] ♪ After 5 hours, we're finally approaching shipwreck site "35F".

♪ For the initial survey, we're deploying the ROV.

♪ [MAN] We're over the target.

Ready to bring down the ROV.

[BOAT CAPTAIN] Yeah.

Copy that.

Over and 10.

[whirring] It's like a remote-controlled submarine, equipped with cameras, sonar, and various sensors which allow the crew to see what's at the seabed.

♪ [ROV OPERATOR] Okay.

Ready for dive in.

♪ The live images are fed to us in the ROV control room.

Hopefully, there are still remains of the shipwreck, and we'll find something down there.

♪ We'll be down in about five minutes to the seabed.

Five minutes to go 330 feet.

Yeah, it's a bit quicker than a dive, eh?

♪ Okay.

So we're 106 metres now.

Should be close to the seabed.

I'm just going to slow my descent.

[speaking all at once] The seabed at 108 and 1/2 metres.

♪ The seabed is over 360 feet below the surface, and right now, there's absolutely no sign of any wreckage.

[MALLORY] Could possibly all be gone, either from um... fishing or it could possibly be covered up by sediment.

[ROV TECHNICIAN] Good timing.

They're coming up on the sonar here.

Okay.

What is this?

Like, I see some kind of... looks like debris or wreck in the sonar, right?

Yeah.

All these bright sections here... - Yeah.

- ...is stuff elevated off the seabed.

Let's head a bit west.

♪ We search the ocean bed for hours and nothing.

♪ And then suddenly, something came up.

♪ Okay.

We've got something hot coming up on the sonar just ahead, to the right.

Wait, that... that right there.

Right there!

Oh, yeah, right.

Just to the bottom of the right screen.

Okay.

I'm gonna move into that and have a closer look.

It's... looks like it could be metallic.

♪ Mallory, what is that?

It's a cannon.

♪ Sasha, can you please put a waypoint down?

We've just located a cannon.

Waypoint placed.

Thank you.

It's the back end of the cannon.

- Oh, okay.

- It's the cascabel.

- You can really see that shape.

- Oh wow.

- That's incredible.

- Wow.

Let's see what else is around there.

This is very good.

Okay.

I am going to move on now to the next target.

Let's pull back in.

We've got a lot of targets to look at.

Wait, wait, wait, slow down.

What's this?

♪ - It's bone.

- That's something.

Hang on, let me just move closer.

I think it's coming now.

That's a tusk.

- What?

- Oh, my God!

Look at that.

Sasha, can you please take a fix?

We found a tusk.

♪ Oh, my gosh.

That's so incredible.

It's been exposed for quite a while.

You see all the growth on it?

These items have been on the sea floor... for, you know, 300, 400 years.

People didn't realize that these merchants were trafficking in Africans and ivory.

Yeah.

So... so finding something like this... So what's the plan now?

Well, I think that we now need to discuss diving operations.

This is what we want to bring up.

Yes, I think this would be important to bring up.

[whirring] Unfortunately, retrieving the tusk is not so simple.

Maritime law forbids mechanical devices from touching artifacts on the ocean floor.

If we want the tusk, we've got to go down and get it.

[whirring] But diving this deep can be very dangerous.

♪ We're talking about 108 metres.

I mean, none of us here... even Kramer, who's a tech diver... that... that's beyond his limits, you know?

That's risky business.

Well, the first question is, should we do it?

Bringing this tusk up is... is going to be raising the voices of people who didn't have a voice.

That tusk was worth maybe even hundreds of lives of slaves.

It's giving people like you and like me an artifact to attach to.

That tusk is a symbol of the pillaging of Africa.

And I think that speaks really, really strongly.

It can help a lot of people identify with that.

Absolutely, you should do it.

But how... how do we do this in the safest way possible?

[RICHARD] It is deep, but there is a way we can dive it safely, using rebreathers and mixed gases.

Everything needs to be aligned perfectly.

We need great conditions, good dive planning, and a great support team.

Well, our options are either tell the story or walk away.

And unless we bring something up, really, we're only telling a portion of the story.

So from what I'm hearing, I guess we're going for it.

I think we should.

I think we can do it.

♪ We return to shore, to gear up for this complicated dive.

♪ As wreck site "35F" slowly decays, and will eventually vanish, the preservation of this crucial bit of history now relies on our success.

♪ Just off of these small islands, only a few hours' sail from where "35F" foundered, relics from the heart of the slave trade were discovered.

The items were salvaged from the wreck of a British slave ship called the "Duoro".

They're key to understanding the transatlantic slave trade.

And for the last few decades, they've been stored in a local diver's garage.

Did you discover the "Duoro"?

Yes, we discovered the "Duoro" back in 1972.

And everything is kept in here.

We've got 30 years of diving work.

♪ All this stuff is from the "Duoro"?

All this stuff is from the "Duoro", yes.

We've found piles and piles of these, which we just didn't know what they were.

And what are they?

Well, later on we discovered that they were manillas, which are slave tokens, and each one of those was worth one slave each.

Let me get this straight.

This is currency.

Currency.

And this fake currency, really... Yes.

...was created to be used in Africa, to buy a human being.

One human being.

Yes, it's quite humbling isn't it, thinking about it really?

Well, I just got goosebumps really, a shudder went through me.

I'm sure.

That's how things were in those days, of course, and they made them in Birmingham.

Shipped them out to the west coast of Africa, filled the ship full of slaves, and took them over to the West Indies.

We probably lifted two or three ton of them.

Thousands.

Piles of these?

Piles.

I mean, they were four foot high, probably as big as this shed.

Apart from these, that are worth one slave, these were worth seven.

That's called an aggry.

Blue glass beads.

We never did find out what these were worth.

Obviously worth more.

Maybe 15 people.

- 15 human beings.

- Possibly, possibly.

I've seen a manilla as big as that.

And they were called "King Manillas".

And they were worth a hundred slaves each.

I guess in a sense it shouldn't surprise us because literally millions of people were trafficked.

Yes.

But we-- but I never knew what they were trafficked for.

I notice something here-- this spoon.

♪ And this spoon-- it brings to life the people who-- the crew.

Mm-hmm.

The people who weren't below.

Life of the traders, not the life of the traded.

That's right.

That's right.

What's that?

- That's an old pocket watch... - No.

...or what's left of a pocket watch.

♪ I didn't show you this.

There's a razor in there.

Oh, wow.

Yeah.

Who would last use that?

This looks like a fork.

It's a silver fork.

Yes, so it would've belonged to a high-ranking officer or the captain because no one else would have silver.

♪ It just suddenly occurred to me just looking at these artifacts, that by themselves, you know, it's a spoon, it's a razor, but really what we have here is a set of two lives.

One is worth nothing.

It's worth this.

And the others they have, you know, he's got a pocket watch, he's got a silver fork, he's got a pipe.

Yeah.

While the people below... - Are dying.

- ...are dying.

They're just squashed in down below as cargo.

- They're... - Cargo.

- ...cargo.

- Yeah.

♪ Sailboats had existed for thousands of years before the transatlantic slave trade.

But one key technological development in the 15th century made it possible to turn the looting of Africa into a business.

PROF NATHALIE: Sailing ships of that era are so beautiful.

It's sort of hard to imagine.

You could go to all the way to West Africa, you could go to Brazil in this.

It's a whole little wooden world.

♪ How did these sails transform the business of the slave trade?

Well, you'll see that the sails are kind of set at an angle, and that's the innovation that we see coming about in the 15th century.

Because before that, sails were set flat and you had to wait for a wind to push the ship from behind but if you didn't get that wind, you couldn't go anywhere.

Whereas with the angle, that meant they could catch the wind from many directions.

They could basically sail into the wind.

So the triangular sails made it all possible?

Yes, this changes the duration.

It changes how far you could go out into the ocean.

It really was an absolute game changer.

And you think of pioneering technology as a positive thing, but it's just heartbreaking that Europeans saw this as an opportunity to really embark on their most evil project.

It really was.

You know, if these sails hadn't been developed, Europeans would never had been able to go southwards, and along the Western coast of Africa to begin taking Africans as enslaved captives.

What were conditions actually like for the captives who then got caught up in that trade?

I think we should go down where the captives would've been held.

And it's very, very steep.

Be careful!

♪ So this is the hold.

And it's really oppressive down here, just the atmosphere and the lack of space.

And the smell, it's so musty you can see there's not really any ventilation.

It would've been utterly terrifying and miserable.

The first thing you have to imagine is the stench.

♪ Hundreds of people all crammed together very tightly.

In some cases, having to urinate and defecate where they're lying.

You would hear them crying, screaming, moaning, begging for death, calling upon their gods to save them.

[faint crying] There were actually diagrams issued which showed the most effective way to pack the largest number of captives into a given space.

And there's not an inch between one person and the next.

[faint coughing and moaning] Some captains did what they called "loose packing".

This was not based on humanitarian reasons, but simply the idea that if they were not so crammed together, they would be less likely to become ill.

Actual time and thought was put into how to design this kind of inhumane arrangement.

Yes, this was the era of the enlightenment.

This is scientific.

Were captives down here ever allowed up there on deck?

There was a concern that their health would suffer if they were not allowed to move around so they would go up on deck, and the captives would be commanded to dance.

If their muscles wasted away, if they were emaciated and withered, they would not sell well.

[shouting and beating] It was so carefully thought through.

Economic values were thought through carefully, the design of the slave ships, the most efficient way to put people in here... I mean this was a very rational kind of a trade.

It's absolutely sinister.

[waves crashing] We've gathered special equipment for the deep diving and we're heading back out to F35's wreck site.

♪ At this time of the year, the best diving conditions are early in the morning.

♪ Our research ship is already halfway there.

♪ The crew will send down the ROV to relocate the wreck site and assist us in retrieving the elephant tusk.

♪ We're on the speedboat not far behind.

♪ Conditions are definitely not optimal.

Today the sea is very choppy.

♪ ROB: I'm just tying these down a little bit better so they won't go flying.

Phil Short and Rich Stevenson, our two tech divers who are going to be going down in excess of 300 feet.

They are two of the best in the world at what they do, and what they do is very dangerous.

They have multiple backup systems in place, because if anything goes wrong down there, that's... it's it.

That's... that's it.

♪ To do it safely and to decompress your body, their bottom time is 20 minutes, and then on the way up, every 10 feet, they have to stop for a minute, and then they have to hang for an hour at 20 feet.

Three hours of ascent from that depth.

It feels like the middle of nowhere.

I can barely see the land.

I was waiting for a big wave to come right over me.

Looks like the weather's getting worse as we push in.

♪ But we're gonna try to keep going forward.

- Working on again a bit.

- Yeah.

- Okay, much better.

- Woo hoo!

♪ [CAPTAIN] Hold on, everybody.

Big wave.

[wave crashing] [MAN] Speedboat, this is Severn Sea.

We're at the shipwreck site.

Conditions are pretty bad out here.

We're being pounded by waves from three directions.

Please stand by for a few minutes while we try to stabilize.

Over.

All right, man.

Yeah.

We're not halfway yet.

I know, I know.

Got a call from the Severn Sea that they're going in circles right now, just to stabilize, because if they stay in one place, everyone's going to be puking.

So they can't drop the ROV in.

So on that grounds, we're going to can today's dive.

It's cancelled?

It is.

Sorry, man.

You've gotta do what you gotta do.

Yeah, sorry.

And we're gonna turn around, which is gonna be miserable, because now we're gonna get pounded because we're gonna be going against the waves.

Gonna come back when the weather's a bit better.

Maybe the sea stays a bit calmer and the ROV ship can deploy.

So it's not great news, I'm afraid, but we will come back.

We will prevail.

♪ So we head back to port, this time, empty-handed.

And to make matters worse, weather reports show this is only the beginning of a major storm.

[waves crashing] So the clock is ticking, and our window of opportunity is getting smaller.

Now we can't do much, other than hope for a short break of good weather.

♪ Many Europeans justified the slave trade by arguing that Africans aided them in the enterprise.

I'm here with Professor Wilhelmina Donkoh, to investigate.

[drum beats] PROF DONKOH: I'll come and support you.

[laughs] That's good to know.

[drum beats] [people singing] [drum beats continue] Can you tell me about the Ashanti practice of domestic slavery in Ghana?

So they still had status.

- It was a low status.

- It was a low status.

But they were still part of the community.

Yes.

How would you describe the difference between the culture of slavery, within Ashanti, compared to the Europeans?

How could the Ashanti could reconcile selling people to Europeans who were going to treat them so much worse?

Has there been any introspection more recently about the Ashanti role in the Transatlantic slave trade?

It's become common for people to blame Africans and say, "Well, they sold their own people and they had slavery before we arrived anyway."

[drum beats] ♪ So after 4 days of waiting, finally the weather has calmed on the English Channel.

We have to take advantage of this short break.

Today is our final opportunity.

♪ Nature does what she likes, whether we have something to accomplish or not.

She's not playing by our time frame.

♪ Beautiful skies, calm water, this is pretty much to get down there and retrieve an artifact from this wreck.

♪ I never even would have imagined myself in this place, with this opportunity to give a voice to the silenced, bringing breath, and breathing new life into people of colour who are currently still living with questions unanswered.

♪ [MAN OVER RADIO] Skin Deep Seeker.

We just received some information from the Severn Sea, that conditions are good.

Over.

Yeah.

That's all copied.

This is it, ma'am.

Really good that Kieran's with me on this dive.

♪ All three vessels have now arrived at the shipwreck site, as the Severn Sea is preparing to lower the remotely operated vehicle.

The ROV will help relocate the shipwreck and help us in our search for the sunken elephant tusk.

♪ [robotic noise fading into screaming] After "35F" unloaded most of the Africans for the auction blocks, almost certainly the Caribbean, it sailed home.

♪ On board may have been gold, bound for the Royal Mint in London, sugar, and a few slaves held back for the British market.

The ships elephant tusks -- African ivory -- were worth more than the human cargo.

♪ It almost made it, but was hit by one of the many storms that lash the English Channel.

Only 45 miles from shore, this slaver went down with everyone on board.

[screaming] [waves crashing] [sonar pings] ♪ All right.

♪ Divers ready.

♪ All right.

Safe divers go out.

[underwater filtered sounds] Richard and Kieran are connecting to the shot line, which was dropped by the ROV.

It will be their only guide to the bottom and back.

Very little sunlight reaches these depths and that makes it much harder to distinguish between top and bottom.

So this wire is also their lifeline.

♪ Skin Deep, Skin Deep.

"Severn Sea" over.

[MAN] "Severn Sea", Skin Deep.

Just for your information, we've launched ROV and we're just taking the clump down now to position it now.

RADIO: Okay then, we'll go and find the shot line and run down effecting.

[whirring] ♪ As the ROV is being maneuvered to the wreck site, directly above it, Rich and Kieran are descending.

It could take them up to 10 minutes to reach the bottom and until then, we will have no contact with them.

♪ Deep diving is much a mental state of mind as it is a physical activity.

We visualize what we're going to do.

We think about the job in hand.

We try to almost foresee any potential problems, and just think through what it is that we've got to do.

♪ The rest of us are all geared up and standing by.

If an emergency happens, we'll jump in to supply Rich and Kieran with extra air tanks and help them in any way necessary.

ROV, that's 50 metres in order with the clump.

Okay.

All stop on the winch.

All stop on the winch.

[whirring] Okay.

ROV is down and in position.

Now we're waiting visual on divers.

On the command bridge, they're waiting to confirm the divers' safety.

♪ They have to see both of them on the ROV's video feed.

♪ [beeping] Visuals on diver now.

I'm seeing one diver.

Still waiting for a visual on Richard.

♪ Kieran has made it to the bottom, but Richard is yet to be seen.

♪ Okay.

There he is, back there.

All right, we can relax a bit now.

Thank you.

After seven minutes of descent, Rich and Kieran are reunited at the seabed.

The ROV has led them right on a pile of rusting cannons.

♪ They find something that looks like a slab of wood.

Likely one of the final remains of the ship's hull.

♪ The Severn Sea is repositioned where the ROV had revealed the tusk.

♪ The crew lower down a basket.

Hopefully it will come close enough for the deep divers to secure the ivory.

♪ Rich and Kieran are searching in a small area.

But it's pitch black all around.

They now have only five minutes to locate the tusk before they have to ascend.

♪ Modern racism didn't begin with the transatlantic slave trade.

♪ In 1449, new laws were enacted in Spain, a big player in the trade.

These were essential for rationalizing treating people as property.

♪ That's very nice to see you, how are you?

Hi, how are you?

- Very nice.

- Fine.

♪ This is a beautiful place.

Yes, it is.

♪ So what did it mean, this purity of blood?

Of Toledo.

♪ In the early 15th Century, Jews and Muslims were forcibly converted to Christianity.

But after the conversions, a new method was invented so as to exclude them from society and growing positions of power.

Until that point, faith was everything.

Yes.

Suddenly, faith was not enough.

No, not enough.

No.

Now it was all about blood.

Yes.

- 1722.

- Yes.

I see the word "genealogy".

So this person who's writing this, he's saying, "Hey, I am pure blood on all four grandparents.

- Nobody has, you know, - Yeah.

...made my blood impure."

- No.

This is pure racism.

- This idea was new.

- Yes.

It made in Europe, for the first time, race a criteria.

[liturgical music] In 1452 the purity of blood legislation led directly to the Pope blessing the slave trade.

When he thought of Africans, he just thought of them as pagans.

- So it was like a code word.

- Yes.

[liturgical music] And when Africans converted to Christianity, did they stop enslaving them?

No.

Purity of Blood.

Africans.

♪ It shows you that bad ideas can go very, very, very far.

Very far.

♪ Severn Sea, Skin Deep and Seeker, status report.

The divers have been at the bottom for more than five minutes now.

They have just under five minutes left until they have to ascend.

Support divers be ready to jump in for decompression phase.

Fingers crossed they'll find a tusk in the next few minutes.

Over.

♪ Those two gentlemen have been someplace that no one else has ever been.

No other person has been on this wreck site.

Ever.

♪ I'm literally above a ship that was carrying my ancestors.

I'm free diving, uh... above kind of a graveyard.

♪ I didn't know the significance of the shipwreck.

I feel more enlightened now.

That's my motivation to spend three, four hours in the water.

That's my personal reward.

♪ With only a few minutes left, the deep divers have found the basket.

The elephant tusk is right next to it.

♪ After almost 350 years at the bottom of the English Channel, remarkably, the tusk is still intact.

♪ Kieran secures the tusk to the basket, which will be hoisted up to the ship.

♪ After 20 minutes on the bottom, with just a few minutes to spare, Kieran and Richard now ascend slowly.

They still have three hours of decompression time to spend in the water.

[CREW MEMBER] I'm gonna put Kinga in first, and you jump straight behind her.

Celebration is still premature as the danger is not over.

In fact, the ascent is one of the most precarious parts of the mission.

We immediately jump in the water to secure Kieran and Richard to make sure they're safe.

♪ Getting down and staying down is the easy part, but managing the ascent is critical because all that time we're at that great depth, we've absorbed a lot of, you know, gas, that has to come out of our bodies in a controlled manner.

And the only way we can do that is by making these decompression stops at a fixed depth for a fixed time.

♪ And worst case, if we have a complete system failure, then we have to rely on you guys to then come down with the additional gases that we will need to continue the ascent.

♪ Kinga, Josh, Kramer and myself have now set up the final decompression station for Rich and Kieran.

If need be, we're ready to grab the gas cylinders and quickly descend to the rescue of the deep divers.

♪ This bar will be hanging for 'em, so when they get to six metres, which is their longest decompression stop, they've got a bar to hold on to, and there's gonna be an emergency gas cylinder with 100% oxygen in, in case they've got any problems.

♪ Did you find a run time for the divers yet?

Not yet.

We're still waiting for them to come up.

♪ Two and a half hours into the dive, we notice air bubbles rising from the deep.

RADIO: Okay.

We're starting to see something down there.

Do you have visual of the divers?

Over.

♪ RADIO: Looks like... yeah, yeah.

There they are.

They're coming to the last station now.

Looks like they're fine.

Yeah.

Roger that.

Divers are fine.

♪ Now that they've made it to the final station, we keep an eye on Rich and Kieran during the last hour of decompression.

If it's not handled properly, exhaustion combined with strong currents of the English Channel can be dangerous for the deep divers, so they must be monitored.

[dolphins whistling] ♪ They've spent almost three and a half hours in the cold Atlantic waters.

A half-hour less than originally planned-- And now we're all back safely on the boat.

♪ Well, it took us a little less time than what we anticipated, didn't it?

♪ The moment we've been waiting for-- we're pulling up the elephant tusk which was pillaged from Africa along with millions of enslaved Africans.

♪ I... I don't know how to describe it.

This is unbelievable.

If it's the final resting place of some of my ancestors, then it's a burial ground.

But it's also a crime scene, because they were taken.

There was an injustice that took place, and no one has ever been brought to account for that.

♪ I want justice for those people.

♪ It always bothers me to use the language "slaves on the ship".

People speak in terms of the Africans on the ships as if they started out as slaves.

They weren't slaves, they were Africans who were enslaved.

♪ Just thinking about the people, they were people.

I can't imagine being torn away from my family.

I can't.

I cannot fathom being taken across oceans I didn't even know existed.

I... and then to be beaten and thrown about and be yelled at in a language I don't even understand and told to do things I do not want to do.

♪ There are generations who think that African history started with slavery.

They think, "Okay.

That's when my history started."

And African history didn't start with African slavery.

African history was interrupted by African slavery.

♪ This is where people who were enslaved were held until it was time for them to be shipped out onto vessels waiting here.

This is the door of no return.

And once they've passed this point, it was the end of life as they knew it.

It was it.

It was the end of their culture, their names would be changed, they would have a life of forced labor.

Their children and their children's children would be born into slavery.

And so this was really the end of their freedom.

♪ Some people say, "Well, don't you feel sorrow when you see this?"

It's still a feeling of anger for me.

- Yeah.

- Okay.

This is what it is.

This is, uh, man's inhumanity to man and this is almost like the--almost the capital of it.

It is.

It's like ground zero.

Yeah.

♪