A circular cairn, roughly 21 metres across and about 2 metres high, sits beneath a covering of peat-grown heather, its perimeter largely absorbed into the bog. On its western side, a smaller heap of stones, about 7 metres in diameter and 1.5 metres high, adds another layer of uncertainty. Whether this secondary feature predates surveyors or was built by them remains unclear; it may be a 19th-century Ordnance Survey trigonometrical station. A 20th-century concrete OS trig pillar stands just east of the cairn's centre, meaning the site has served as a navigational reference point twice over, separated by perhaps a hundred years.

The cairn's deeper significance lies at its north-north-east edge, where a line of four large stones extends inward from a point about 3 metres inside the perimeter, trending towards the centre. The stones are substantially buried, which makes interpretation difficult, but archaeologist Seán Ó Nualláin, writing in his 1989 survey of the megalithic tombs of County Sligo, noted that they could represent tomb structure, possibly the remnants of a passage tomb. A passage tomb is a type of Neolithic monument in which a stone-lined corridor leads to a burial chamber, often covered by a circular mound; County Sligo contains some of the most significant concentrations of such monuments in Ireland, most famously on the Carrowmore plain and the summit of Knocknarea. The cairn at Doomore fits the broader landscape pattern, looking out over Ballysadare Bay from a commanding elevation. But it remains, officially, a site of uncertain status, its stones too buried and too altered by later use to speak clearly about what was first built there, or when.