© The Automobile Association 2008. © Crown Copyright Licence number 100021153
1 From the uphill corner of the car park, a faint path slants down to the old road, which is now a well-used track. Head up-valley for about 650yds (594m). With the old road continuing as a green track ahead, your path now bends down to the right. It has been rebuilt, with the bog problem solved by scraping down to the bedrock. The path reaches the gorge where the River Coe runs in a geological dyke of softer rock. Descend on a steep wooden step ladder, to cross a spectacular footbridge.
2 The ascent out of the gorge is on a bare rock staircase. Above, the path runs through regenerating birch wood, which can be very wet on the legs; sheep and deer have been excluded from the wood with a temporary fence. Emerge over this by a high ladder stile. The path, rebuilt in places, runs uphill for 60yds (55m). Here it bends left; an inconspicuous alternative path continues uphill, which can be used to bypass the narrow path of the main route.
3 The main route contours into the gorge of the Allt Coire Gabhail. It is narrow with steep drops below. Where there is an alternative of rock slabs and a narrow path just below, the slabs are more secure. You will hear waterfalls, then two fine ones come into view ahead. After passing these, continue between boulders to where the main path bends left to cross the stream below a boulder the size of a small house. (A small path runs on up to right of the stream, but leads nowhere useful.) The river here is wide and fairly shallow. Five or six stepping stones usually allow dry crossing. If the water is above the stones, then it's safer to wade alongside them; if the water is more than knee-deep the crossing should not be attempted.
4 A well-built path continues uphill, now with the stream on its right. After 100yds (91m) a lump of rock blocks the way. The path follows a slanting ramp up its right-hand side. It continues uphill, still rebuilt in places, passing above the boulder pile that blocks the valley, the result of two large rockfalls from under Gearr Aonach opposite. At the top of the rockpile the path levels, giving a good view into the Lost Valley.
5 Drop gently to the valley's gravel floor. The stream vanishes into the gravel, to reappear below the boulder pile on the other side. Note where the path arrives at the gravel, as it becomes invisible at that point. Wander up the valley to where the stream vanishes, ¼ mile (400m) ahead. Anywhere beyond this point is more serious hillwalking than you have done up to now on this walk. Return to the path and follow it back to the start of the walk.