This is a souterrain, an underground chamber or tunnel built from drystone walling, typically associated with early medieval settlement in Ireland and thought to have served as storage space, a refuge, or both. What makes this particular example quietly compelling is how precisely the archaeology has preserved its proportions: the side-walls are corbelled, meaning each course of stone projects slightly inward over the one below, gradually closing the gap until the roofing lintels can span what remains. It is a technique requiring no mortar, only patience and a good eye for weight.

The souterrain sits just off the southern side of a circular hut foundation, the two structures forming a small domestic cluster on a levelled terrace half a metre above the surrounding ground. The terrace itself is revetted, meaning its edge is faced with large upright slabs to hold the shape of the platform. The hut circle measures roughly 6.85 metres by 6.3 metres, its outline still defined by standing stones. The souterrain passage runs off to the north-east from its low opening at the terrace base. T. J. Westropp, writing in 1912, noted a fort on the flank of Cool Hill on the Iveragh Peninsula, and this site is thought to correspond to that reference, though the word fort in his context likely described a broader enclosed settlement rather than anything militaristic. The archaeological record for this part of south Kerry, documented by A. O'Sullivan and J. Sheehan in their 1996 survey of the Iveragh Peninsula, places both structures within a wider landscape of early habitation across this stretch of the southwest coast.