There is an excellent description of this walk is in Jim Ryan’s guidebook Carrauntoohil & MacGillycuddy’s Reeks. A word of caution, this is a climb up a steep gully where at times use of hands will be necessary. The upper part of the gully can be quite wet. While the ground is steep, the gully is wide and grassy, with very little loose rock. Start at the hydro road car park, walk around the Coomloughra lakes on the north eastern side and start the ascent by following the river at the south east end of Lough Eagher. Initially, the climb is up an obvious wide gully. In the upper reaches of the gully, it sub-divides into three narrower gullies. According to Ryan’s guidebook, any of the three can be used to get to the ridge. I used the left side gully. Carrauntoohil is less than 15 minutes from the top of the gully. I returned by Caher, but Beenkeeragh is the obvious alternative.