The opening, less than a metre wide and barely forty centimetres tall, sits in the western interior of the enclosure, but the passage beyond it is choked with debris and has been for some time. A souterrain, as these underground passages are known, was typically used in early medieval Ireland for storage or as a place of refuge, and the fact that this one remains sealed adds a particular quality of unfinished business to the site.

The rath itself sits in flat pasture on the north bank of the Inny river in the townland of An Toileán Buí on the Iveragh Peninsula. It is well preserved, with an enclosing bank of earth and stone that reaches up to 2.5 metres in external height and averages about 5.5 metres across at its base, enclosing an interior roughly 25 metres across. There are three gaps in the bank, which is not unusual in older ringforts, but which of them served as the original entrance is unclear; the northern gap is considered likely to be a later addition. The Ordnance Survey Name Books recorded two placenames in this townland, Lios Mór and Lios Beag, meaning the large fort and the small fort respectively, and it is thought that this enclosure and a neighbouring site together account for those two names, a pairing that quietly implies a settled, organised presence here across centuries of occupation.