A crannog is an artificial or partly artificial island, typically built from layers of timber, stone, peat, and brushwood, and used as a dwelling place from the Bronze Age well into the early medieval period and occasionally beyond. Thousands of them are known across Ireland, concentrated particularly in the lakelands of the west and midlands, and yet individually they remain among the least visited and least understood of all Irish monument types. The one at Rinnaseer is, for now, a name on a map and little more.

The frustrating truth about this site is that detailed records have not yet been made publicly available, which means that the usual particulars, who built it, when it was in use, what excavation or survey work if any has been carried out, remain out of reach for the general reader. What can be said is that crannogs in Mayo tend to occupy small lakes and loughs scattered across boggy, low-lying ground, and that they were chosen for the natural defensive advantage water provided. Inhabitants would have reached them by dugout canoe or along a submerged timber causeway. Some Irish crannogs were occupied continuously for centuries; others appear to have served as seasonal retreats or places of refuge during periods of conflict. Without more specific documentation for Rinnaseer, placing this particular example within that wider picture is not yet possible.