The Cairngorm ski area car park is good in that you are starting out from high altitude already, though you may want to leave a note with some authority telling them your car reg, and when you are due back so that you don't spark an unnnecessary hunt for yourself! Another good starting point is by Glen More Lodge, heading up the track towards Ryvoan and turning up towards Loch Avon (pronounced A'an) for some spectacliar scenerery around the head of Loch A'an.
The hike through the Lairig Ghru is renowned for roughness and grandeur of geological sights, you could combine this with a trek through to Derry Lodge (good areas by the river for camping, then up Glen Derry to Loch A'an and back over to Ryvoan and down to Glen More or some variant route over the tops. October is an interesting time in the Cairngorms; the midgies and cleggs die off and the air is cool and autumnal, with the roaring of stags in the rut echoing across the hillsides. Beware of rutting stags getting too stroppy; they can be dangerous. Wet and windy weather conditions are more likely than snow, though snow can happen any time high up in the hills, it is unlikely to lie in any amount that would cause problems in October. Let's assume you are sensible enough to seek shelter if the weather turns bad; there are bothies/shelters at Corrour, Ryvoan, Shelter Stone at the head of Loch A'an, Etchachan near Loch Etchachan, Bob Scotts downstream from Derry Lodge and a mountain rescue hut (locked when not manned) near Derry Lodge. In Glen Feshie there is Ruigh Aiteachain bothy.Try searching this forum for posts on routes through the Carngorms, and stags...
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- Lairig ghru sunrise
- Stag Nation