The Cuillin (Scottish Gaelic: An Cuilthionn or An Cuiltheann) are a range of rocky mountains located on the Isle of Skye in Scotland. The true Cuillin are also known as the Black Cuillin to distinguish them from the Red Hills across Glen Sligachan. The Red Hills are lower and, being less rocky, have fewer scrambles or climbs.
The highest point of the Cuillin, and of the Isle of Skye, is Sgurr Alasdair in the Black Cuillin at 992 m (3,255 ft). The Cullin Hills is one of 40 National Scenic Areas in Scotland.
The Black Cuillin are mainly composed of basalt and gabbro, the latter being a very rough rock which makes for superb grip for mountaineers. It is from the dark colour of the gabbro that the Black Cuillin receive their name. The summits of the Cuillin are bare rock, jagged in outline and with steep cliffs and deep cut corries and gullies. All twelve Munros on Skye are Black Cuillin peaks, though one of them, Blaven, is part of a group of outliers separated from the main ridge by Glen Sligachan.
The scrambler can access most of the individual peaks by their easiest routes. Only the Inaccessible Pinnacle is a graded rock climb (moderate) by its simplest line but several of the other summits require scrambling skills.
In addition to climbing individual peaks, there is the challenge of a full traverse of the ridge. Although only seven miles in length, the average traverse is likely to take 15–20 hours from sea level at Glenbrittle to the bar of the Sligachan Hotel owing to the difficulty of the terrain and route finding problems. The first recorded traverse in under 24 hours was in 1911 by L Shadbolt and A McLaren. The record for the full traverse, set by Es Tresidder in May 2007, stands at 3 hours 17 minutes (though this time is from Gars-bheinn to Sgurr nan Gillean and does not include the initial ascent from Glenbrittle or the final descent to Sligachan).
A longer traverse of the Black Cuillin, (including all the Munros, though omitting some gabbro outliers) is the Greater Traverse; this involves continuing on to Clach Glas and Blaven. This traverse was first done independently by two parties, in the summer of 1939, with I Charleson and W Forde claiming precedence over W. H. Murray & R G Donaldon a few weeks later. - (see Bill Murray's book for details of his traverse).
Some believe the ultimate mountaineering experience of the UK is the full traverse under winter conditions. The Isle of Skye's position in the warm Gulf Stream makes genuine winter conditions rare, and the very short winter days probably make a 24-hour traverse impractical. The first recorded, over two days, was in 1965 by D Crabbe, B Robertson, T Patey and H MacInnes.
The Cuillin is perhaps the only range in the United Kingdom to approach in sheer jagged rawness (though not of course in height) the mountain experience of such ranges as the Alps or Rockies.