Each step is roughly 0.45 metres wide, and the whole structure was engineered not around a reliable spring but as a ground-run water-collection system, drawing together whatever moisture the island could yield. For a religious community living on a low-lying sliver of land only about 120 metres from the mainland, the ability to hold fresh water was a practical necessity, and the well was most likely dug out and deliberately enlarged to serve that purpose. At some point in the twentieth century, a scholar named Henry looked at it and concluded it was a souterrain, an underground stone-lined passage typically associated with early medieval settlement, used for storage or refuge. The well sat misclassified in the literature until later excavations corrected the record.

Illaunloughan, known in Irish as Oileán Lócháin, carries an uncertain name. It may commemorate a saint called Lochán, a figure mentioned twice in the Martyrology of Oengus, a liturgical calendar composed around AD 800, and potentially also connected to the inland ecclesiastical site of Killoughane on the eastern end of the Iveragh peninsula. Alternatively, an older Ordnance Survey name book suggested the island name may simply mean the island of the chaff. No historical documentation has been found to settle the question either way. Four seasons of archaeological excavation between 1992 and 1995 uncovered roughly seventy per cent of the island, revealing a monastic complex that includes an oratory and a circular hut, with this well positioned midway between them. The well was already marked on the 1892 Ordnance Survey 25-inch map, and was conserved in 2001 and 2002. Excavation of the well itself yielded nothing of particular archaeological significance, which in its own way is telling: it was a working feature of a living community, used up, and left empty.