0:00:28 > 0:00:34This coast might be inhospitable, but that hasn't deterred generations of invaders.
0:00:35 > 0:00:37The Vikings landed here
0:00:37 > 0:00:41and sited their capital at the harbour village of Scalloway.
0:00:43 > 0:00:47These islands feel very different from the rest of Scotland.
0:00:47 > 0:00:51They were under Norwegian rule right up until the 15th century.
0:00:51 > 0:00:55The ties to Norway are very, very strong.
0:00:55 > 0:01:00They were never stronger, though, than during the Second World War.
0:01:04 > 0:01:08In 1940, Nazi Germany invaded Norway.
0:01:08 > 0:01:15Shetland's neighbour needed help and the North Sea offered a lifeline to Norwegian resistance fighters.
0:01:15 > 0:01:21The islands became the base for a daring, secret operation - the Shetland Bus.
0:01:22 > 0:01:29The Bus was a fleet of fishing boats which smuggled people out and agents in to occupied Norway.
0:01:32 > 0:01:35Many lives were saved and many lost.
0:01:35 > 0:01:40The islanders have never forgotten the sacrifice of these men.
0:01:41 > 0:01:43The names, the age,
0:01:43 > 0:01:46when they died and the boats they were on.
0:01:46 > 0:01:5123, 28, 21, 21, just wee boys.
0:01:51 > 0:01:53Just boys.
0:01:53 > 0:01:57'Karen Anderson's father was one of the Norwegian sailors who survived.
0:01:57 > 0:02:02'At 23 years old, Kaare Iversen risked everything for his homeland.'
0:02:02 > 0:02:07So how did your dad get involved in that story?
0:02:07 > 0:02:10Dad escaped from Norway
0:02:10 > 0:02:13in 1941
0:02:13 > 0:02:15on his father's boat.
0:02:15 > 0:02:19They came across to Shetland and he was approached
0:02:19 > 0:02:23to see if he was suitable for the Shetland Bus and he was.
0:02:23 > 0:02:27Most of their missions were carried out in winter
0:02:27 > 0:02:33when the dark nights provided some cover for the 500-mile round trip across the North Sea to Norway.
0:02:35 > 0:02:38Ammunition was stored at Scalloway Castle
0:02:38 > 0:02:43while resistance fighters and refugees found shelter with the locals.
0:02:47 > 0:02:51The men became heroes. After the war, their bravery was celebrated
0:02:51 > 0:02:56in the Norwegian feature film Shetlandsgjengen, The Shetland Gang.
0:03:02 > 0:03:08It was very dangerous because they didn't know what they were going across to Norway to face.
0:03:08 > 0:03:13The weather was against them and the Norwegian fishing boats they were using weren't big.
0:03:13 > 0:03:17He said if he was captured that they all had a cyanide pill to take,
0:03:17 > 0:03:21rather than be interrogated by the Germans.
0:03:22 > 0:03:27Losses were heavy. Over 100 died in storms or German attacks.
0:03:30 > 0:03:33But many lives were saved.
0:03:33 > 0:03:38By the end of the war, more than 350 refugees had been carried to safety.
0:03:45 > 0:03:51- How much does the story of the Shetland Bus still mean to people in Shetland?- A great deal.
0:03:51 > 0:03:53I'm very proud of my dad. Really.
0:03:53 > 0:04:00I cannot say in words how I feel about what...not only him, but what other Norwegian boys did.
0:04:00 > 0:04:05That's part of Scalloway's history. Always will be.
0:04:26 > 0:04:29These islands have provided safe refuge to many.
0:04:29 > 0:04:34Its rich, unspoilt coastline is a haven for wildlife.
0:04:34 > 0:04:38Seals are at home in these well-stocked waters
0:04:38 > 0:04:41and there is a large population of otters.
0:04:44 > 0:04:50- Welcome aboard.- 'I'm catching a ride with skipper Tom Jamieson who knows the seas off this coast.'
0:04:50 > 0:04:55- All right, Tom?- Hello, Neil. - What kind of wildlife is out here?
0:04:55 > 0:04:59- We've had minke whales.- Right. - And also killer whales.
0:04:59 > 0:05:04We never used to see killer whales. There are more of them around now.
0:05:06 > 0:05:10These waters aren't just teeming with wildlife.
0:05:10 > 0:05:15North Sea shipping passes the southern tip of Shetland on its way to the Atlantic.
0:05:17 > 0:05:22At Garths Ness, one vessel's journey would end in disaster.
0:05:23 > 0:05:27At 5.10am on the 5th of January, 1993,
0:05:27 > 0:05:31the coastguard received a distress call from the crew of an oil tanker
0:05:31 > 0:05:36whose engines had broken down ten miles off the coast of Sumburgh Head.
0:05:37 > 0:05:43Gusts of up to 97 miles an hour were driving the oil tanker Braer ashore.
0:05:43 > 0:05:47After a six-hour struggle, she ran aground.
0:05:48 > 0:05:5384,000 tonnes of toxic crude oil spewed out into the sea,
0:05:53 > 0:05:58creating the worst environmental disaster ever to hit the British coast.
0:06:00 > 0:06:06Coastguards managed to winch the crew to safety, but Shetland's wildlife was not so lucky.
0:06:06 > 0:06:13Sea bird colonies, seals, shellfish, fish hatcheries, grazing bays were all badly polluted.
0:06:16 > 0:06:21Shetland braced itself for the worst. The storm raged for almost a month,
0:06:21 > 0:06:24seriously hampering the clean-up campaign.
0:06:24 > 0:06:29But the brutal power of the waves started to work in the islanders' favour.
0:06:29 > 0:06:35Ultimately, the sea's power broke up the oil and helped clean up the shores.
0:06:37 > 0:06:43The sheer force of the pounding water acted like a giant washing machine,
0:06:43 > 0:06:46churning up the oil and dispersing it out to sea.
0:06:48 > 0:06:52These islands are constantly at the mercy of the elements.
0:06:52 > 0:06:56But on this occasion, nature came to the rescue.
0:07:09 > 0:07:14Shetland may feel like a different world to the mainland,
0:07:14 > 0:07:17but to some people, it is the mainland.
0:07:17 > 0:07:2024 miles out to sea is Fair Isle.
0:07:21 > 0:07:25Three miles long and a mile and a half wide,
0:07:25 > 0:07:29you're only ever three-quarters of a mile from the sea here.
0:07:29 > 0:07:34This is home to fewer than 80 people, many drawn here by a way of life
0:07:34 > 0:07:37that is hard to find anywhere else in the UK.
0:07:37 > 0:07:41'..thundery rain or showers, moderate or good.
0:07:41 > 0:07:48'Fair Isle, south, four or five, occasionally six, becoming variable, three or four.
0:07:48 > 0:07:53'Rain or showers, moderate with fog patches, occasionally good later.'
0:07:53 > 0:07:59'I think lots of people will know of Fair Isle from the shipping forecast.'
0:07:59 > 0:08:0512.4. 'I'm Dave Wheeler, I'm a weather observer on Fair Isle,'
0:08:05 > 0:08:11doing regular weather observations every hour of the day from six in the morning till six at night
0:08:11 > 0:08:14for 35 years now.
0:08:17 > 0:08:1912.4.
0:08:20 > 0:08:230.1 millimetre of rain.
0:08:23 > 0:08:28'People do ask me quite frequently what the weather is going to do.'
0:08:30 > 0:08:32Tomorrow will not be too bad a day.
0:08:32 > 0:08:35I think it looks like it'll change.
0:08:37 > 0:08:41- 'I hope I can give them a good service.'- Thank you very much.- Bye!
0:08:41 > 0:08:45'If I'm wrong, they don't hold it against me.'
0:08:45 > 0:08:47Hello, puss.
0:08:47 > 0:08:50This is the sunshine recorder.
0:08:53 > 0:08:56Hmm, no sun. Surprise, surprise!
0:08:59 > 0:09:02And we said what visibility?
0:09:02 > 0:09:0650 metres visibility, dense fog.
0:09:06 > 0:09:09We hope for a better day tomorrow.
0:09:11 > 0:09:15'Fair Isle, south, four or five, occasionally six,
0:09:15 > 0:09:19'moderate with fog patches, occasionally good later.'
0:09:23 > 0:09:26Over 67 different islands make up Orkney,
0:09:26 > 0:09:31or, as they were known to their Viking rulers, Orkneyjar - Seal Islands.
0:09:34 > 0:09:40Nowadays, the island-hopping lifestyle of the locals has led to a unique claim to fame.
0:09:43 > 0:09:49People come from all over the world to fly less than two miles between Papa Westray and Westray.
0:09:55 > 0:10:00Here we are then, wheels up, on the world's shortest scheduled flight.
0:10:00 > 0:10:04I have to say it's all going very well so far.
0:10:04 > 0:10:07This journey usually takes a couple of minutes,
0:10:07 > 0:10:13but it's been done in just 69 seconds when it made the Guinness Book of Records.
0:10:13 > 0:10:19Somebody once told me that the most dangerous part of flying is taking off and landing.
0:10:19 > 0:10:23But that's all this flight is - a take-off and a landing.
0:10:23 > 0:10:27This flight might seem extravagant, but the £14 fare is subsidised
0:10:27 > 0:10:30because it's an important link for these remote communities.
0:10:30 > 0:10:33And we're down!
0:10:40 > 0:10:44Tourism certainly adds to the traffic around Orkney,
0:10:44 > 0:10:50but 260 years ago, it was trade that dominated these waters and navigation was a nightmare.
0:10:54 > 0:11:00These islands, like the rest of the British Isles, were surrounded by largely uncharted waters.
0:11:00 > 0:11:05But in the 18th century, that was all about to change.
0:11:07 > 0:11:14Over in Kirkwall, Mark Horton is discovering how one Orcadian made our seas safer.
0:11:16 > 0:11:20In 1743, a curious advertisement turned up
0:11:20 > 0:11:24in newspapers and coffee houses throughout Britain.
0:11:24 > 0:11:30A local schoolmaster from here in Orkney, Murdoch Mackenzie,
0:11:30 > 0:11:34planned to make a really detailed chart of these treacherous waters,
0:11:34 > 0:11:39but was desperately needing sponsors to help pay for his ambitious project.
0:11:42 > 0:11:46'Orkney was the hub for North Atlantic trade routes,
0:11:46 > 0:11:51'but hazardous tides and uncharted seas meant shipwrecks were common.
0:11:53 > 0:11:56'With finance from traders and merchants,
0:11:56 > 0:12:00'Murdoch Mackenzie set about charting Orkney's coast
0:12:00 > 0:12:05'in ways that would revolutionise map-making around the world.
0:12:09 > 0:12:14'Local sailor Sandy Firth has studied Mackenzie's pioneering work.
0:12:14 > 0:12:18'He even owns a rare copy of his original survey.'
0:12:18 > 0:12:22So is this the actual folio of charts?
0:12:22 > 0:12:27Yes, one of them. That's it, the bound edition of Mackenzie's survey.
0:12:27 > 0:12:29- 1750.- 1750.
0:12:29 > 0:12:35Mackenzie was the first man to start putting in these symbols.
0:12:35 > 0:12:38They indicate the nature of the bottom of the sea.
0:12:38 > 0:12:43He gives you the state of the tide at different times
0:12:43 > 0:12:46and the direction of it.
0:12:46 > 0:12:49- No-one had bothered to do that up till then?- No.
0:12:49 > 0:12:54Mackenzie's symbols that you'll see here are still used to this day in Admiralty charts.
0:12:54 > 0:12:57I've got a good idea.
0:12:57 > 0:13:00I want to go and actually survey this bay
0:13:00 > 0:13:06and let's see if we can actually make a map using the same methods that Mackenzie used himself.
0:13:06 > 0:13:09'Mackenzie devised a method
0:13:09 > 0:13:15'of charting any position at sea by using fixed reference points on land.'
0:13:15 > 0:13:17- There we go, spot on.- Yeah.
0:13:17 > 0:13:22- Around 69 degrees roughly. - 69 degrees.
0:13:22 > 0:13:25"A" to second lamp-post...
0:13:25 > 0:13:31'Mackenzie realised it wasn't only essential for sailors to know where they were at sea,
0:13:31 > 0:13:35'but also what hidden dangers were lurking under the water.
0:13:35 > 0:13:42'He gathered samples from the ocean floor, using a rope and lead weight covered in tallow - animal fat.'
0:13:42 > 0:13:46The tallow should pick up what's on the bottom, shouldn't it?
0:13:49 > 0:13:53- We've got the two bits of leather there.- Two fathoms.
0:13:53 > 0:13:56Two fathoms and...
0:13:58 > 0:14:04- That looks like mud on the bottom. - Genuine mud.- Genuine mud, just like Mackenzie did it.- Yeah.
0:14:05 > 0:14:11'Murdoch Mackenzie's methods changed the way we view the underwater world.
0:14:11 > 0:14:16'Over 260 years after he first charted the coast of Orkney,
0:14:16 > 0:14:22'the science of surveying he did so much to inspire has advanced to this.
0:14:27 > 0:14:32'This coastguard vessel is equipped as a state-of-the-art survey ship.
0:14:37 > 0:14:43'Rob Spillard is one of the officers whose mission is to boldly go
0:14:43 > 0:14:47'where the charts may not necessarily be reliable.'
0:14:47 > 0:14:54- You can see just to the south of Green Holm here, there's a 26-metre contour.- Absolutely, yes.
0:14:54 > 0:14:58That's where we had an incident just a few days ago.
0:14:58 > 0:15:00A vessel grounded just off that island.
0:15:00 > 0:15:05It's done about a million pounds' worth of damage to the vessel
0:15:05 > 0:15:10and they put in a note saying the 26 metres was wrong. They claim to have grounded at 11 metres.
0:15:10 > 0:15:17We'll try and prove if the chart is right or wrong and make it safer for anybody else making the same passage.
0:15:18 > 0:15:21'This is real detective work.
0:15:21 > 0:15:26'There's an obstruction hidden out there that's already wrecked one vessel.
0:15:26 > 0:15:29'Next time, it may be fatal.'
0:15:30 > 0:15:33So how do you measure depth in the 21st century?
0:15:33 > 0:15:40As opposed to doing it with a lead line and a linesman and measuring maybe one depth every minute or two,
0:15:40 > 0:15:43we can measure several thousand depths every second.
0:15:43 > 0:15:49We send out pings of sound into the water underneath the ship and listen for their return.
0:15:49 > 0:15:52'The quicker the echo, the shallower the water.
0:15:52 > 0:15:57'By measuring return data, the team can produce a remarkably clear picture
0:15:57 > 0:15:59'of what lies below the surface.
0:15:59 > 0:16:06'This German U-Boat from the First World War was discovered on the sea bed just off Orkney.
0:16:08 > 0:16:13'But today, we're looking for something much nearer the surface -
0:16:13 > 0:16:16'an obstruction that has caused serious damage.
0:16:16 > 0:16:23'The ship is sailing back and forth over the suspicious area, gathering thousands of depth readings.'
0:16:23 > 0:16:27We're just going past where the vessel ran aground.
0:16:27 > 0:16:32On this screen, you can see all the rockiness on the starboard side of the vessel,
0:16:32 > 0:16:37- so you should see the rock as we come close to it.- As we go over the top of the rock.
0:16:40 > 0:16:43- The depth under the keel is that figure?- Yeah.
0:16:43 > 0:16:49As we get closer to where the vessel grounded, that will decrease as the sea bed comes up to meet us.
0:16:49 > 0:16:55When that figure goes to about five metres, that's when we've really got to run for the life jackets.
0:16:55 > 0:17:01- So the obstruction could still be out here?- Yeah, it is quite touch and go, actually.
0:17:01 > 0:17:07'Already the soundings are showing that the charted depth of 26 metres is wrong,
0:17:07 > 0:17:12'but what we don't yet know is just how close below us these rocks are lying.'
0:17:12 > 0:17:1512, 11...
0:17:17 > 0:17:20We should be keeping our fingers crossed... 10!
0:17:20 > 0:17:23This is terrifying.
0:17:23 > 0:17:25We've gone down to 9.
0:17:27 > 0:17:30RAPID BEEPING
0:17:30 > 0:17:34'And then we find it, just 7.5 metres below us,
0:17:34 > 0:17:40'a massive rock, much closer to the surface than charted and a major risk to shipping.'
0:17:40 > 0:17:46If we had gone over that at very low tide, we'd have been very, very close to touching it.
0:17:46 > 0:17:53- So that's the structure of the rock? - You see the crinkles and crevices. This area is made of rock.- Amazing!
0:17:54 > 0:17:59'We're about to make a new mark on the chart of our coastal waters.
0:17:59 > 0:18:03'I'm sure Murdoch Mackenzie would have approved.'
0:18:05 > 0:18:08And really what's so amazing
0:18:08 > 0:18:13- is we could do it with this technology and it just took an afternoon to do.- So quickly.
0:18:13 > 0:18:17With a lead line, it would have taken a long, long time to do.
0:18:17 > 0:18:24- New technology doesn't just save money, but lives too.- Absolutely. - A good day's work.- We did well.
0:18:24 > 0:18:28Subtitles by Subtext for Red Bee Media Ltd 2009
0:18:28 > 0:18:31Email subtitling@bbc.co.uk