Episode 15 Coast

Beaches, boats and bicycles.

I must be in Denmark.

Winds whip over northern Jutland.

Its famous walking dunes

have engulfed whole villages,

so conifers and grasses were planted to anchor the landscape.

But not everywhere has been pinned down.

A small desert has been left to roam free,

the Rabjerg Mile, a magic carpet of sand.

This entire dune system is ceaselessly on the move.

The whole thing began its journey over there on the west coast

and it's moving across country towards the east.

In 200 years or so this huge ocean of sand

will have travelled cross-country from coast to coast.

The surreal shifting sands of this fairy-tale world stretch down to the sea.

Don't stand around too long or you'll get gobbled up.

Now, this towering sand dune

is surely impressive enough, but I'm told there's a sight

at the top of it that's nothing less than spectacular.

Look at that!

That's like a special effect from a film about the end of the world.

Lighthouses, as we all know,

are built for protection from the power of the sea.

How ironic, then, that this tower

should have been overwhelmed by a much slower-moving wave...of sand.

The light was lit for the first time in 1900

and finally extinguished in 1968,

when the crew of this place had to admit defeat.

Some 1,600 years ago, people from hereabouts in Jutland

began getting in boats and heading for Britain.

They left behind their own sandy shores

and headed instead for the fertile lands of Kent

and the Isle of Wight.

The Jutes of Jutland were followed some 500 years later

by more famous and fearsome Danes, the Vikings.

Over on the east coast is Roskilde.

It's an ancient capital of Viking power.

Here, over 1,000 years ago,

they planned raids on Britain, as Alice is about to explore.

The cathedral at Roskilde is built on the site of a tenth-century Viking church.

Generations of Danish monarchs are buried here.

But there's one Danish king who's missing from Roskilde,

someone whose remains are buried in Winchester Cathedral.

That's because in the early 11th century

King Canute was the ruler not just of Denmark but of England.

Canute was a colossus of the Viking world.

He didn't only reign in Britain and Denmark,

but also Norway and part of Sweden.

In the ninth and tenth centuries the Vikings were THE European superpower.

Each year, Roskilde throws a party to honour their warrior ancestors.

The secret of Viking power wasn't the sword or the axe,

but a weapon that guaranteed them speed and stealth.

This is a reconstruction of the ultimate tenth-century war machine,

the longship.

This one is called a Sea Stallion,

and she's based on an actual Viking longship

that was excavated from the fjord here at Roskilde.

She looks absolutely beautiful sitting here in the calm waters

of the harbour, but I do wonder just how seaworthy she really is.

I've been offered the unique opportunity of signing up

for her 60-strong crew, but this is no free ride.

It's hard physical work

but it's quite relaxing in a weird way as well...

..the rhythmic nature of it,

and there's a little pause at the end of each stroke where you just get to catch your breath.

This isn't a pleasure cruiser. The Sea Stallion's a living laboratory.

Building and sailing a replica of the ship found in this fjord

has given the archaeologists a valuable insight into Viking technology.

Luckily for us when it was found

most of the keel and some of the floor timbers were found,

so by looking at that, the reconstructors were actually able to estimate

the design, the length, the width and also the depth of the ship

from, actually, just looking at those 25%.

So do you think that King Canute would have had similar ships

when he brought his fleet over to Britain?

I would expect so, yeah. At least a few of them would be this size.

And this size of ship, this was exclusively a warship?

Yeah, a warship is always long and narrow and has a shallow keel.

In 2007, to discover how Viking warriors like Canute

crossed from Denmark to attack the British Isles,

the Sea Stallion followed in their wake,

attempting a hazardous voyage across the North Sea.

When I first saw the ship lying there in the harbour

she looked beautiful but it was hard to imagine

how she was going to perform on the open sea, so how does she perform?

That was a big question for me too in heavy sea and heavy weather.

It's a wonderful ship, it's a wonderful ship.

I'm amazed how it's coping with these big waves,

five metres of waves and very steep, short waves.

-Five metres?

-Five metres...

Because, I mean, this rides very low in the water.

Yes, it's not one metre, so looking up at these waves coming, "Argh!"

Then you feel out there that it's a seagoing warship.

So can you imagine King Canute taking his army across to Britain in ships

like this, can you imagine what it would have been like for them?

We were over there in one ship.

They would have been sailing maybe 200 ships.

It must have been an incredible sight.

In 1015, Canute invaded England with a fleet of these ships.

It probably took him just three days' sailing from Denmark,

his vessels both fast and seaworthy.

When the longships reached the British coast,

their shallow draft meant they could navigate up the rivers

to take the English by surprise.

Canute claimed the crown of England

and cemented a relationship with our monarchy that has spanned the centuries,

which explains why Canute, King of Denmark and England,

doesn't rest here in Roskilde,

but back in Britain at Winchester Cathedral.