The mountain's main ridge goes Southwest from the summit to a col with a height of 923 metres. Here it splits, with one spur swinging round the head of Coire an Lochain to go eventually north and link to the adjoining Munro of Stob Coire Sgriodain. The other spur continues southerly to link to Meall Garbh (976 metres) which is listed as a top in Munro's Tables and has steep crags on its eastern flank. The south side of Chno Dearg contains the steep-sided Coire nan Cnamh which falls precipitously to the glen of the Allt Feith Thuill, a tributary of the River Ossian. All drainage from the mountain reaches the River Spean to the north where it flows to the west coast of Scotland.