Located on an east-facing slope with rock outcroppings nearby, this subterranean structure sits roughly 900 metres from Tramore Strand beach and about a kilometre from Dunfanaghy’s estuarine bay. Despite its substantial size, the souterrain managed to escape official notice for decades; it never appeared on any Ordnance Survey maps and wasn’t formally recorded until the National Museum of Ireland documented it in 1968.

This drystone construction stretches for approximately 20 to 21 metres in a distinctive L-shaped configuration. The main passage extends about 14 metres east to west before turning sharply northward for another 7 metres. Throughout its length, three strategic constrictions divide the souterrain into four distinct sections, with an additional small chamber branching off to the north. These narrow passages, measuring barely a metre wide and less than that in height, force visitors to crouch or crawl through the entire structure. The construction follows the natural contours of the hillside, with one section sloping noticeably downward from west to east, whilst the central passage curves in a gentle, sinuous pattern.

The building technique reveals both practical construction and careful planning in specific areas. The side walls consist of three to five rough courses of angular stones of varying sizes, with massive boulders forming the base in some sections. The constrictions, however, show more deliberate craftsmanship, featuring upright jamb stones projecting from the walls and topped with low-set lintels. Large horizontal slabs form the roof throughout, though several now show worrying cracks and displacement, suggesting the structure’s vulnerability to further collapse. The sandy earth floor and multiple areas of surface subsidence above ground hint at the souterrain’s precarious state, whilst the true extent of the passages remains uncertain, as both the northern and eastern ends may simply be blocked rather than original terminals.