A crannog, the Irish term for a lake dwelling typically built during the early medieval period, this one takes the form of a circular cairn roughly twenty-two to twenty-three metres across and two metres high. It sits about thirty metres from the north-western shore, and beneath the waterline it continues for at least another five metres down, suggesting a structure of considerable original mass, now largely obscured by vegetation and time.

What makes the site particularly legible, even in its overgrown state, is the timber framework still visible along the eastern shoreline of the island. At least sixteen radial beams survive, some as small as ten centimetres square and a metre long, others up to thirty centimetres square and five metres in length, with wooden pegs driven in at roughly half-metre intervals. Alongside these lie at least twenty-six vertical piles. This kind of construction, using timber piles and horizontal beams to consolidate and extend a man-made island platform, is characteristic of crannogs across Ireland and Scotland, where lake dwellings served variously as defensible residences, places of storage, or high-status settlements. The presence of quern stones, the flat grinding stones used to mill grain by hand, and hone stones used for sharpening blades, on the surface of the cairn gives some sense of the ordinary domestic and working life that once took place here. The lake itself is subrectangular, roughly three hundred and seventy to five hundred metres along its north-east to south-west axis, nestled within the rolling glacial landscape that defines this part of Monaghan.