A souterrain, to use the technical term, is a man-made subterranean structure, typically built from dry-stone walling and roofed with large flat slabs, used in early medieval Ireland as a place of refuge, storage, or both. They are found across Ireland in considerable numbers, yet each one represents a deliberate act of labour and concealment, a community digging down and roofing over a secret space for reasons that were pressing enough to justify the effort.

The Doonty example sits within a broader landscape that, across Mayo and the western seaboard generally, preserves an unusually dense record of early settlement. Souterrains are most commonly associated with ringfort settlements, the enclosed farmsteads that dot the Irish countryside in their thousands and date broadly from the early centuries of the first millennium through to the Norman period. The passages could be entered from within the enclosure, offering a discreet exit or a cool, dark chamber for storing dairy produce. In times of raid, they offered concealment. The specific details of this particular souterrain, its dimensions, its current condition, and its precise relationship to any surrounding monument, are not well documented in the available record.