The GR 400 circumnavigates the Puy Mary Volcano by loops, the itinerary presented here is the biggest loop one can make on this trail. You mainly follow the ridgeline for a while, then go down in the valley to go back up to the next ridge line. It´s a beautiful itinerary with a lot of open views, a lot of springs where you can find some clear water, and trails that are just a joy to run on.

The route passes through the spectacular landscapes of Glen Affric and Kintail connecting the two towns of Drumnadrochit, on the famous Loch Ness, and Morvich, on the spectacular Scottish West Coast. Whilst the route stays relatively low, cutting a line of least resistant through this rugged and remote part of the country, it takes in the huge views of the Five Sisters of Kintail, the Glen Affric munros, and Loch Affric.