The structure at its centre is a crannog, an artificial or partly artificial island built from timber, stone, and earth, typically used as a defended dwelling during the early medieval period in Ireland. This particular example rises 2.5 metres above the lake-bed, making it unusually prominent, and its oval profile measures around 24 metres east to west and just over 20 metres north to south.

The mound itself sits at the south-eastern end of the lough, in the rolling drumlin landscape characteristic of this part of the midlands. Drumlins are elongated hills formed by glacial action, and their terrain tends to produce irregular, enclosed lakes, which made them attractive locations for crannog builders. At the south-eastern portion of this crannog, a smaller raised area, about 11 metres by 10 metres and rising to 0.8 metres, sits unevenly on the main mass, its surface grassy and lumpy underfoot. Around its edges, the stones are blackened and shattered in a way that suggests exposure to fire at some point, though whether through deliberate burning, accidental destruction, or the lime-processing sometimes associated with such sites is not clear from what surveyors observed. The submerged plateau surrounding the mound varies in character depending on which direction you look: to the north, flagstones and broken material rest on soft, gaseous mud, while the southern edge is steeper and carries a heavier mud content. There is also a local tradition associating the crannog with a stone sculpture, though when the site was examined the object was not found.