The island on which I reside lies at the northern end of the Outer Hebrides, and is actually the largest island off the mainland of Great Britain. Lewis and Harris (one landmass) stretch for 80 miles between the Butt of Lewis in the north and Rodel in the south. On a clear day, visibility extends for 75 miles, as I discovered some time ago.
The two humps on the horizon are the Red Hills by Broadford in Skye, as I said, 75 miles to the south of Stornoway. This picture was taken on 10 February, when visibility was very good. You can see from Cape Wrath all the way down to Kyle of Lochalsh; Cape Wrath is visible at night particularly on account of the lighthouse, whose flashes can be discerned from just below the horizon as you stand near the Butt of Lewis. The mountains on the mainland stand out at this time of year, wreathed in snow.
From my own viewpoint in Stornoway, I can make out the hills around Applecross on a clear day (like this afternoon), a mere 60 miles to the southeast.