This is a souterrain, an underground stone-lined tunnel or chamber built in early medieval Ireland, most often associated with ringforts and thought to have served as storage space, refuge, or both. What makes this particular example quietly arresting is not what survives but what can be inferred: two short exposed sections of passage, separated by a ten-metre ridge of disturbed stone running east to west, which may mark the buried line connecting them.

The souterrain lies within a univallate ringfort, meaning a circular enclosure bounded by a single earthen bank or stone wall, which also contains the remains of a circular hut. The underground passages are built in drystone construction, with flat stones laid without mortar to form the side-walls and a flagged roof. The first visible section runs for two metres, is aligned roughly northwest to southeast, and stands no more than 35 centimetres high at present, too constricted for anyone to enter. The second section, to the north of the hut, is slightly more generous at four metres long, 55 centimetres wide, and around half a metre high, though its drystone walling and flagged roof survive only in the southwestern half. Both ends are blocked by collapse, and what was once a roofed passage elsewhere has become an open, unfaced hollow. The full extent of the souterrain remains uncertain. The site was documented by J. Cuppage in the 1986 Dingle Peninsula archaeological survey, a comprehensive study of the Corca Dhuibhne region published by Oidhreacht Chorca Dhuibhne.

The site sits in rough, fairly level pastureland, and the two exposed passage sections give a reasonable sense of the original engineering even in their degraded state. The stony ridge between them is easy to overlook as agricultural disturbance, but read alongside the passages it suggests a more extensive underground system, most of which remains buried or lost to collapse beneath the western slopes of Ballysitteragh.