The Okrney Islands are connected to the UK mainland by the Northern Lights Cable, terminating at Dunnet Bay. The Orkney end is at Skail.
The path is shown in detail on the Cable Awareness Chart: http://www.seafish.org/media/Publications/Northern_Lights_Flyer_Web.pdf
The cable lands near Skara Brae neolithic village (you can see the visitors centre in the bottom of the photo below. If you look at the original imagery on Google Earth you can just see the disturbed ground in the field matching the alignment in the above image.
The sea cable almost certainly terminates in the manhole by the field gate at the bend in the road, before heading south.
In fact a search for “Skara Brae Cable Landing” brings up a document with a photo of the landing at Skail Beach.