Measuring roughly 33 metres across, the island sits in the northern reaches of the lough and is constructed of stone, its interior rising about two metres above summer water levels. That rise is significant. Enough elevation to stay above seasonal flooding, enough regularity of shape to suggest deliberate engineering rather than glacial accident.

The island belongs to a broader tradition of artificial or semi-artificial lake islands known as crannogs, structures built from timber, stone, and brushwood that were used across Ireland from the Bronze Age through to the early modern period, often as defensible dwellings or places of refuge. Whether Lady's Island follows that pattern precisely is not recorded, but its construction from stone and its carefully maintained height above the waterline are consistent with that tradition. A breakwater extends some six metres to the southwest from the island's base, a detail that hints at regular use and deliberate access management. To the northwest, the remains at Castlecarra are visible across the water, placing this small island within a landscape that was clearly occupied and organised over a long period. By the time D. Lavelle's archaeological survey of the Ballinrobe district was compiled in 1994, the interior had become very overgrown, its stonework obscured beneath vegetation.