A souterrain, which is an underground stone-built tunnel or chamber typically associated with early medieval settlement, runs north to south under the ground here, largely intact but no longer accessible. What makes it visible at all is a stroke of accidental fortune: one of the large flat roofing slabs has collapsed inward, opening a small window into the chamber below. Through that gap, it is possible to peer down into a space that was carefully constructed, and then quietly forgotten.

The chamber itself is modest in its dimensions, roughly one metre high and about 1.2 metres wide, with at least 3.4 metres of length confirmed, though the true extent is unknown. The walls are of drystone construction, built without mortar, and they corbel slightly inward as they rise, a technique that gives the structure a degree of stability and lends it a subtle, almost organic shape. A series of large flat slabs laid across the top would have made the whole thing effectively invisible from above, seamlessly buried beneath the laneway. At the northern end, the western portion of the end wall has collapsed, but the eastern jamb of a low opening survives at ground level, which appears to have led into a creepway or further passage. The southern end is entirely blocked by collapse, though local knowledge suggests the souterrain continued in that direction beyond what can now be measured or seen. The site sits at the northeastern edge of a clachan, the Irish term for a cluster of rural dwellings, at Caheracruttera, a detail that places this underground feature within a wider pattern of early settlement on the peninsula. The description of the site was documented by J. Cuppage in the 1986 Dingle Peninsula archaeological survey, Corca Dhuibhne.

The souterrain is not accessible, and the laneway above it gives little away. What can be seen through the collapsed roof slab offers just enough to suggest the care that went into its construction and the questions that remain about where else it might have gone.