The island is 78 hectares (193 acres - about a third of a sq. mile) in area and rises to a maximum height of 153 metres (502 feet). The name Muldoanich is the anglicised version of the Gaelic 'Maol Dòmhnaich'.
Muldoanich stands just outside Castlebay the main port on the Isle of Barra and it is a prominent landmark for the ferry approaching Castlebay. It has no level ground and is uninhabited.