Mullach nan Coirean has four ridges radiating from its summit. The eastern ridge links to the adjoining Munro of Stob Bàn which is three kilometres away, whilst the south western ridge links to the subsidiary top of Meall a' Chaorainn (910 metres) before descending steeply to the glen of the River Kiachnish. The northern ridge is four kilometres long and has the vitrified fort of Dùn Deardail (Fort of the Red Eye) near its terminus just before it joins Glen Nevis. The fort is probably named after Deirdre, the princess of Ulster, it is one in a line of vitrified forts that stretches from Craig Phàdraig outside Inverness to the west coast. The north east ridge also descends to Glen Nevis but is much shorter. The mountain's lower northern slopes are covered by the coniferous woodland of the Nevis Forest.