0:00:15 > 0:00:18Beaches, boats and bicycles.
0:00:18 > 0:00:20I must be in Denmark.
0:00:49 > 0:00:52Winds whip over northern Jutland.
0:00:52 > 0:00:54Its famous walking dunes
0:00:54 > 0:00:56have engulfed whole villages,
0:00:56 > 0:01:01so conifers and grasses were planted to anchor the landscape.
0:01:01 > 0:01:04But not everywhere has been pinned down.
0:01:04 > 0:01:08A small desert has been left to roam free,
0:01:08 > 0:01:11the Rabjerg Mile, a magic carpet of sand.
0:01:16 > 0:01:21This entire dune system is ceaselessly on the move.
0:01:21 > 0:01:24The whole thing began its journey over there on the west coast
0:01:24 > 0:01:27and it's moving across country towards the east.
0:01:27 > 0:01:30In 200 years or so this huge ocean of sand
0:01:30 > 0:01:34will have travelled cross-country from coast to coast.
0:01:37 > 0:01:43The surreal shifting sands of this fairy-tale world stretch down to the sea.
0:01:43 > 0:01:47Don't stand around too long or you'll get gobbled up.
0:01:50 > 0:01:52Now, this towering sand dune
0:01:52 > 0:01:56is surely impressive enough, but I'm told there's a sight
0:01:56 > 0:02:00at the top of it that's nothing less than spectacular.
0:02:10 > 0:02:12Look at that!
0:02:12 > 0:02:16That's like a special effect from a film about the end of the world.
0:02:20 > 0:02:22Lighthouses, as we all know,
0:02:22 > 0:02:25are built for protection from the power of the sea.
0:02:25 > 0:02:28How ironic, then, that this tower
0:02:28 > 0:02:33should have been overwhelmed by a much slower-moving wave...of sand.
0:02:37 > 0:02:40The light was lit for the first time in 1900
0:02:40 > 0:02:42and finally extinguished in 1968,
0:02:42 > 0:02:46when the crew of this place had to admit defeat.
0:02:56 > 0:03:00Some 1,600 years ago, people from hereabouts in Jutland
0:03:00 > 0:03:03began getting in boats and heading for Britain.
0:03:03 > 0:03:06They left behind their own sandy shores
0:03:06 > 0:03:09and headed instead for the fertile lands of Kent
0:03:09 > 0:03:10and the Isle of Wight.
0:03:10 > 0:03:15The Jutes of Jutland were followed some 500 years later
0:03:15 > 0:03:19by more famous and fearsome Danes, the Vikings.
0:03:21 > 0:03:25Over on the east coast is Roskilde.
0:03:25 > 0:03:29It's an ancient capital of Viking power.
0:03:29 > 0:03:31Here, over 1,000 years ago,
0:03:31 > 0:03:35they planned raids on Britain, as Alice is about to explore.
0:03:39 > 0:03:45The cathedral at Roskilde is built on the site of a tenth-century Viking church.
0:03:45 > 0:03:48Generations of Danish monarchs are buried here.
0:03:58 > 0:04:03But there's one Danish king who's missing from Roskilde,
0:04:03 > 0:04:07someone whose remains are buried in Winchester Cathedral.
0:04:07 > 0:04:11That's because in the early 11th century
0:04:11 > 0:04:16King Canute was the ruler not just of Denmark but of England.
0:04:21 > 0:04:24Canute was a colossus of the Viking world.
0:04:24 > 0:04:27He didn't only reign in Britain and Denmark,
0:04:27 > 0:04:30but also Norway and part of Sweden.
0:04:30 > 0:04:35In the ninth and tenth centuries the Vikings were THE European superpower.
0:04:40 > 0:04:44Each year, Roskilde throws a party to honour their warrior ancestors.
0:04:44 > 0:04:47The secret of Viking power wasn't the sword or the axe,
0:04:47 > 0:04:51but a weapon that guaranteed them speed and stealth.
0:04:58 > 0:05:03This is a reconstruction of the ultimate tenth-century war machine,
0:05:03 > 0:05:04the longship.
0:05:04 > 0:05:06This one is called a Sea Stallion,
0:05:06 > 0:05:09and she's based on an actual Viking longship
0:05:09 > 0:05:13that was excavated from the fjord here at Roskilde.
0:05:13 > 0:05:16She looks absolutely beautiful sitting here in the calm waters
0:05:16 > 0:05:22of the harbour, but I do wonder just how seaworthy she really is.
0:05:33 > 0:05:36I've been offered the unique opportunity of signing up
0:05:36 > 0:05:41for her 60-strong crew, but this is no free ride.
0:05:45 > 0:05:47It's hard physical work
0:05:47 > 0:05:51but it's quite relaxing in a weird way as well...
0:05:52 > 0:05:56..the rhythmic nature of it,
0:05:56 > 0:06:02and there's a little pause at the end of each stroke where you just get to catch your breath.
0:06:03 > 0:06:08This isn't a pleasure cruiser. The Sea Stallion's a living laboratory.
0:06:08 > 0:06:12Building and sailing a replica of the ship found in this fjord
0:06:12 > 0:06:17has given the archaeologists a valuable insight into Viking technology.
0:06:17 > 0:06:19Luckily for us when it was found
0:06:19 > 0:06:22most of the keel and some of the floor timbers were found,
0:06:22 > 0:06:27so by looking at that, the reconstructors were actually able to estimate
0:06:27 > 0:06:33the design, the length, the width and also the depth of the ship
0:06:33 > 0:06:36from, actually, just looking at those 25%.
0:06:40 > 0:06:43So do you think that King Canute would have had similar ships
0:06:43 > 0:06:45when he brought his fleet over to Britain?
0:06:45 > 0:06:51I would expect so, yeah. At least a few of them would be this size.
0:06:52 > 0:06:55And this size of ship, this was exclusively a warship?
0:06:55 > 0:07:00Yeah, a warship is always long and narrow and has a shallow keel.
0:07:08 > 0:07:12In 2007, to discover how Viking warriors like Canute
0:07:12 > 0:07:16crossed from Denmark to attack the British Isles,
0:07:16 > 0:07:19the Sea Stallion followed in their wake,
0:07:19 > 0:07:23attempting a hazardous voyage across the North Sea.
0:07:26 > 0:07:29When I first saw the ship lying there in the harbour
0:07:29 > 0:07:32she looked beautiful but it was hard to imagine
0:07:32 > 0:07:35how she was going to perform on the open sea, so how does she perform?
0:07:35 > 0:07:41That was a big question for me too in heavy sea and heavy weather.
0:07:41 > 0:07:44It's a wonderful ship, it's a wonderful ship.
0:07:44 > 0:07:48I'm amazed how it's coping with these big waves,
0:07:48 > 0:07:52five metres of waves and very steep, short waves.
0:07:52 > 0:07:54- Five metres?- Five metres...
0:07:54 > 0:07:57Because, I mean, this rides very low in the water.
0:07:57 > 0:08:02Yes, it's not one metre, so looking up at these waves coming, "Argh!"
0:08:02 > 0:08:08Then you feel out there that it's a seagoing warship.
0:08:08 > 0:08:11So can you imagine King Canute taking his army across to Britain in ships
0:08:11 > 0:08:15like this, can you imagine what it would have been like for them?
0:08:15 > 0:08:18We were over there in one ship.
0:08:18 > 0:08:21They would have been sailing maybe 200 ships.
0:08:21 > 0:08:23It must have been an incredible sight.
0:08:25 > 0:08:30In 1015, Canute invaded England with a fleet of these ships.
0:08:30 > 0:08:35It probably took him just three days' sailing from Denmark,
0:08:35 > 0:08:38his vessels both fast and seaworthy.
0:08:38 > 0:08:41When the longships reached the British coast,
0:08:41 > 0:08:44their shallow draft meant they could navigate up the rivers
0:08:44 > 0:08:47to take the English by surprise.
0:08:47 > 0:08:50Canute claimed the crown of England
0:08:50 > 0:08:55and cemented a relationship with our monarchy that has spanned the centuries,
0:08:55 > 0:08:59which explains why Canute, King of Denmark and England,
0:08:59 > 0:09:01doesn't rest here in Roskilde,
0:09:01 > 0:09:04but back in Britain at Winchester Cathedral.