The enclosure is D-shaped in plan, a form that was achieved here not through any elaborate construction on the seaward side but simply by letting a shoreline cliff, two to three metres high, do the work. Only where the land approach required it did the builders raise a bank of earth and stone, and even that is relatively modest, standing no more than a metre high on the interior.

The fort measures roughly 29.5 metres along its north-west to south-east axis and about 17.3 metres across. The enclosing bank, between 2.6 and 4.1 metres wide, curves around the landward arc of the site before petering out, leaving deliberate or degraded gaps where it meets the shoreline. There is no fosse, the defensive ditch that typically accompanies earthen banks of this kind, which may indicate either an original design decision or significant later erosion and alteration. The original entrance has not been identified. Inside the enclosure, towards the south-east, a shallow linear depression, roughly a metre wide and just twenty centimetres deep, runs on a north-east to south-west alignment. Its function is unclear; it may represent the last trace of a structure, a drainage channel, or simply a crease in the ground that has resisted centuries of weathering. Promontory forts of this type, which use natural coastal features to reduce the amount of artificial fortification required, are found at intervals along the Irish coastline, though their dating is rarely straightforward and their occupation histories tend to be poorly understood.