It stretches roughly 130 metres north to south and spreads about 40 metres wide, a shape that looks less like deliberate engineering than like something the sea itself arranged. That widened, flattened profile is almost certainly not what its builders intended, and that gap between intention and present reality is where the interest lies.

The breakwater extends from the northern shore of the harbour, with a deliberate gap near its southern end through which boats can pass into the calmer, sandy-bottomed anchorage to the east. A shorter continuation, around 40 metres long, picks up again on the far side of that entrance and runs to the southern shore. The structure was almost certainly once narrower and considerably taller, offering more substantial shelter. Centuries of south-westerly Atlantic storms appear to have gradually pushed stone from the crest eastward, progressively lowering and broadening the bar into its present form. Local tradition holds that the breakwater was built by the Vikings, who needed reliable anchorages along the exposed south-west coast during their period of activity in Irish waters. Whether or not that attribution is provable, it is not implausible; the Norse were experienced harbour engineers, and a sheltered inlet on the Beara Peninsula would have been genuinely useful.

The structure is best seen at low tide, when the full extent of the stone bar is exposed. The anchorage it protects is still used by local fishermen, which gives the place an unbroken practical continuity that purely ruined sites rarely have.