Roughly circular, measuring about 6.6 metres across and less than a metre high, it rises gently from the eastern edge of a natural rise in the ground, with wet land spreading out to the north-east. At its south-south-west edge it has been worn down over time, and hawthorn and brambles have taken hold there, softening what remains of its profile. Loose stones are scattered across its surface, and a slightly raised rim defines the top at the north and north-west, though some of that edging may be no more than field clearance stones piled up by farmers over the generations.

What makes the Coolnaha mound worth pausing over is not its scale but its company. About twenty metres upslope to the west lies an embanked barrow, a type of prehistoric funerary monument in which a burial mound is enclosed or defined by an earthen bank. The two features sit close enough together to suggest this small corner of Mayo once carried some significance in the prehistoric landscape, even if the precise nature of that significance has not been determined. The mound at Coolnaha may itself be the remains of a burial monument, though the accumulation of field clearance material over the centuries makes it difficult to read with confidence. Its position on the eastern lip of raised ground, overlooking the wet lowland to the north-east, is the kind of placement that recurs with low earthen monuments across Ireland, neither commanding nor hidden, but occupying a considered point in the terrain.