This one, in the townland of Creeharmore in County Roscommon, does something quietly different: it occupies an inland ridge jutting into the flood-plain of the River Suck, borrowing the same tactical logic from a landlocked landscape. The river runs roughly north to south about 120 metres to the west, and the ridge itself trends northwest to southeast, leaving a narrow peninsula of elevated ground that an earthen bank and ditch could seal off with a single defensive stroke.

The structure that does that sealing is a flat-topped, grass-covered earthen bank running roughly northeast to southwest, cutting across the western end of the peninsula. It stretches about 130 metres in length, with a base width of around 8 metres narrowing to roughly 2.5 metres at the top, and rises to a height of approximately 1.6 metres on its outer face. In front of it lies a rounded fosse, the term for a defensive ditch dug to complement a bank, measuring about 8 metres across at the top and between 2 and 3 metres at its base, though now quite shallow at around 0.6 metres deep. The bank and fosse are noticeably degraded toward the northeast end, and a wide gap of roughly 8 metres at the centre, where the fosse also disappears for about 50 metres, is thought to have been enlarged by later quarrying activity rather than representing an original entrance of that width. The interior of the enclosed area runs to about 120 metres along its longer axis, and within it sit two further monuments: a rath, which is a roughly circular earthen enclosure typically associated with early medieval settlement, and a mound whose original function is not specified but whose presence suggests the site accumulated significance across more than one period of use.

The combination of features at Creeharmore, a promontory fort wrapping around a rath and a mound, points to a landscape that was returned to, built upon, and repurposed over a long stretch of time. The river flood-plain setting, which would have made the surrounding ground boggy and difficult to cross at certain times of year, clearly made the ridge worth defending, even without a cliff or sea inlet to do half the work.