This is The Pentalina, she is a catamaran ferry operating between Gill's Bay, near John O'Groats on the northern Scottish coast and St Margaret's Hope, South Ronaldsay, towards the southern end of the Orkney mainland.
I have been away for a couple of weeks, wandering around Orkney and Shetland.
I had arrived on Orkney a few hours earlier via The Pentalina. Behind her are the island of Flotta, with part of the Oil Terminal visible, and the mountainous island of Hoy.
The Oil Terminal opened in 1976, to handle crude oil from the North Sea, and load into tankers to deliver to other refineries.