0:00:24 > 0:00:29Hoy means "high island" and that's exactly what this is.
0:00:29 > 0:00:33These sea cliffs are some of the most impressive in Britain.
0:00:44 > 0:00:50Two climbers have set out to tackle Orkney's most famous landmark.
0:00:57 > 0:01:03The Old Man of Hoy stands 450 feet tall on the shores of the Pentland Firth.
0:01:05 > 0:01:09This magnificent sea stack used to be attached to the headland,
0:01:09 > 0:01:14but the elements have slowly eroded the soft red sandstone to create this solitary pinnacle.
0:01:17 > 0:01:23No-one knows how much longer the Old Man will stand before he falls into the sea.
0:01:28 > 0:01:32This morning, driving rain and strong winds greeted Andy Cave
0:01:32 > 0:01:36and fellow climber Simon Nadin at the start of their ascent.
0:01:36 > 0:01:42- Are you excited, Simon?- 'In this weather, the slippery unstable rock is even more dangerous.'
0:01:42 > 0:01:46- Not looking in its best conditions, I must admit.- Yeah.
0:01:46 > 0:01:48Better than being in the office though.
0:01:48 > 0:01:51- Maybe.- Definitely.
0:01:51 > 0:01:54But despite the conditions, they've decided to give it a go.
0:01:54 > 0:02:00I'm off to catch up with the guys to find out what makes this stack the one every climber wants to bag.
0:02:07 > 0:02:10Simon and Andy have been climbing for three hours.
0:02:10 > 0:02:15The weather has improved and their chances of reaching the top are looking better.
0:02:23 > 0:02:26'Hello, Andy. It's Neil, can you hear me?'
0:02:26 > 0:02:28All right, Neil, how's it going, mate?
0:02:28 > 0:02:30I'm fine but then I'm on the mainland.
0:02:30 > 0:02:33How's it been going so far?
0:02:33 > 0:02:38We were a bit worried really because it's been raining and in the mist it was very easy to slip off.
0:02:38 > 0:02:42Our hands were covered in green slime and our feet were covered in bird poo
0:02:42 > 0:02:44so it was just horrible, very insecure.
0:02:44 > 0:02:50But I think now we are less worried and just concentrating on the job really.
0:02:50 > 0:02:51Right, I'll let you crack on.
0:02:55 > 0:03:00The Old Man was first conquered in 1966.
0:03:00 > 0:03:05It was a three man team - Chris Bonington, Tom Patey and Rusty Baillie.
0:03:05 > 0:03:10Even Everest had been climbed many years before anyone knocked off this monster
0:03:10 > 0:03:14and it was such a success that the climb was recreated the following year.
0:03:14 > 0:03:17That time, the TV cameras were in attendance.
0:03:20 > 0:03:22Covering the ascent for television
0:03:22 > 0:03:25was as challenging as climbing the Old Man himself.
0:03:25 > 0:03:28Everything had to be brought from the mainland.
0:03:28 > 0:03:3330 tonnes of equipment were hauled over the moors to create an outdoor studio.
0:03:34 > 0:03:37It was the first live programme of its kind.
0:03:37 > 0:03:40Over 20 million viewers tuned in over three nights
0:03:40 > 0:03:46to watch Chris Bonington and his team make nail-biting television history.
0:03:46 > 0:03:52Somewhere there are four climbers, four radio cameramen.
0:03:52 > 0:03:56There you can see the radio camera men on the gallery.
0:03:56 > 0:04:04This is the hardest move on this, I think. I have somehow got to turn round here
0:04:04 > 0:04:08and I've got rather a bad hand-jam right inside the crack.
0:04:08 > 0:04:10I've got to swing right round.
0:04:15 > 0:04:21Climbing the Old Man of Hoy today is just as demanding and no less dangerous.
0:04:30 > 0:04:32- That's nice.- Nice finish.
0:04:32 > 0:04:36It took the original team two days to find a route to the summit.
0:04:36 > 0:04:41Climbing in their footsteps, it's taken our guys around five hours.
0:04:42 > 0:04:43Nice one.