It is in Lochaber, south of Loch Arkaig and north of the road west of Fort William (from which it is usually climbed).

It is composed of banded granite and shaped like a letter Y, with two tops connected by a ridge running from northeast to southwest, with the northern top 6 m higher than the one to the south.

Crags drop at either end, and steep slopes fall away to either side.

The south ridge path is really a stream bed, so in wet conditions an easier if longer ascent from Na Socachan is to walk up Allt a Choire Reidh towards Gualann nan Osna and climb the south top's north-west ridge.

According to Ainmean-Àite na h-Alba, the name comes from Gadhail Bheinn, meaning "mountain of the hunting dogs" (gadhar).