The island itself is subcircular, roughly 24 metres north to south and 21 metres east to west, its edges defined by a platform of stones and peat. That combination of materials is not accidental: in this part of Connacht, peat and stone were the ready building blocks of early settlement, and together they could be shaped into something surprisingly durable.

The site is classified as a cashel, a term for a stone-walled ringfort, the kind of enclosed farmstead that was the basic unit of rural life in early medieval Ireland, broadly from the sixth to the twelfth centuries. Inside the island perimeter, a central mound of peat rises to about 1.7 metres and slopes gently southward. In the southern half of the interior there is a small rectangular depression, 1.5 metres long and a metre wide, the purpose of which is not recorded but which might suggest a storage pit, a hearth setting, or some other domestic feature now difficult to read from the surface. What makes the whole arrangement particularly coherent is the causeway: a well-preserved stone-built path, 1.15 metres wide, that runs south-west from the island for over 21 metres before turning south for a further 3.7 metres to meet the shore. The deliberate angle suggests the builder was working around the local topography of the lakebed, choosing the firmest or shallowest route rather than cutting straight across.