For stunningly jagged, unforgiving and otherworldly landforms, look no further than the Isle of Skye in the Inner Hebrides. This unofficial 128km/79-mile trail takes walkers along the Trotternish Ridge (including the Old Man of Storr, pictured) and underneath the incomparable stony backbone of the Cuillin Ridge.
More experienced climbers and mountaineers can even attempt to traverse the Cuillin Ridge (with the help of a local guide). The traverse totals 12km with 4,000m/123,000ft of ascent. Finlay Wild currently holds the speed record – an insane 2 hours, 59 minutes and 22 seconds. The challenge takes most two days, with 16-20 hours of climbing.