This is a souterrain, an underground passage or chamber built from drystone masonry, typically constructed during the early medieval period in Ireland and associated with settlement enclosures. They may have served as cool storage spaces, refuges, or escape routes. At Coarha More, the passage runs to about 4.5 metres in length, curving as it extends outward from inside the hut, and its side-walls still stand to a height of roughly 0.9 metres, though the lintel stones that once formed the roof have been robbed out and removed, probably centuries ago.

The site is part of a wider enclosed settlement. A stone-faced earthen bank, stretching some 6.6 metres, runs radially inward from the enclosing bank on the eastern side, dividing the interior in a way that suggests the space was deliberately organised. A shallow subrectangular depression in the north-eastern sector of the site, measuring around 3 metres by 1.3 metres, has stone-lining along part of its edges, hinting at a structure or feature whose precise function is no longer clear. An opening detected on the eastern exterior of the hut may indicate that the souterrain extended further in that direction, though the passage as it now exists is filled with debris and any continuation remains unconfirmed. The details of the site were compiled by A. O'Sullivan and J. Sheehan in their 1996 archaeological survey of the Iveragh Peninsula, published by Cork University Press, which remains a key reference for early settlement patterns across this part of south Kerry.