Ordinarily one to two metres below the waterline, it is invisible to any passing eye, and the Ordnance Survey maps record no crannog here at all. The only indication that anything lies beneath is a pole marking the spot, an understated signal for what may once have been a place of considerable power.

A crannog is an artificial or partly artificial island, typically built out into a lake and used as a defended dwelling, and this example is thought to measure around fifteen metres in diameter. Though it escapes the OS record entirely, it does appear, labelled simply as 'the Island', on a series of late sixteenth-century maps of County Monaghan: one produced by Browne and Bocazio around 1590, and two by Jobson, dating to around 1591 and 1598. The fact that cartographers of that period took note of it is itself telling. Researcher McDermott has argued that, as a high-status site, it may have served as a base for the McKenna leadership, one of the Gaelic families prominent in this part of Ulster, potentially into the sixteenth century. The crannog sits at a boundary point where four townlands meet, a location that may have carried symbolic weight as much as strategic value, placing the seat of authority at a contested or liminal point in the landscape.

Emy Lough itself is a compact, roughly rectangular lake, around 700 metres north to south and 600 metres east to west. The pole marking the submerged cairn remains the only visible sign of the site from the southern shore, and the lake's surface gives nothing else away.