What it exposed was a souterrain, an early medieval underground stone structure, typically associated with Irish ringforts and used for storage or refuge. Then, just as quickly as it had appeared, the structure was filled back in. The entire recorded existence of this souterrain above ground amounts to a single inspection, conducted while the passage was still waterlogged and partially collapsed.

Despite the disturbance, enough survived to allow a reasonably precise description. The souterrain consisted of a short passage leading through a narrow creepway into a well-preserved rectangular chamber. Creepways are exactly what they sound like, deliberately low and confined connectors between sections of a souterrain, presumably to slow or deter intruders. This one was just 0.65 metres long, 0.56 metres wide, and only 0.46 metres high, roofed by two flat slabs. More unusually, halfway along the creepway, movement was further restricted by a porthole slab, a stone into which a neatly cut round arch had been formed, carved from a slab roughly eight to ten centimetres thick. The chamber beyond it was considerably more generous, measuring 3.55 metres in length and 1.3 metres in both width and height, its drystone walls slightly corbelled inward so that by roof level the space had narrowed to just 0.63 metres across. Five large slabs formed the roof; one had already been removed, and with both the creepway and chamber flooded to a depth of 0.3 metres at the time of inspection, that gap provided the only means of access. The description was recorded by J. Cuppage and published in the 1986 Dingle Peninsula archaeological survey of the Corca Dhuibhne region.