The sea does most of the defensive work on three sides; the builders only needed to address the landward approach, and they did so with some care. Across the northeast end of the promontory they threw up two parallel banks separated by two fosses, the kind of earthwork arrangement a specialist would call a bivallate defence. A causeway 4.5 metres wide cuts through both lines, presumably where an entrance once stood.

The scale of the earthworks gives a sense of the effort involved. The outer fosse runs about 40 metres in length, is 4 metres wide, and drops roughly three quarters of a metre below the surrounding ground before rising 1.5 metres to the crest of the outer bank. The inner bank is more substantial still, about 7 metres wide at the top, with its fosse rising 2.5 metres to the summit. Just inside this inner bank, near the entrance, two shallow circular depressions roughly 1.5 metres across are outlined by grass-covered stones. These have been tentatively identified as possible guard-chambers, small rooms flanking a gateway where sentries might have kept watch, though the remains are too indistinct to be certain of that reading. The earthworks were described in detail by J. Cuppage in the 1986 Dingle Peninsula archaeological survey. Scattered across the landward approach are several sub-rectangular hollows that have nothing to do with the original fort; local tradition holds that these were used in the recent past for storing seaweed, cut from the shoreline and kept close to hand for use as fertiliser on the thin coastal fields.