Measuring roughly nineteen metres on its longest axis, it is not a natural feature but a deliberately constructed one, built up from the lakebed and enclosed by a dry stone wall. The site is recorded as a cashel, a term for a stone-walled ringfort, though here the enclosure sits not on solid ground but on a man-made platform in open water, placing it closer in spirit to a crannog, the artificial lake islands used as defended dwellings throughout early medieval Ireland. The combination of the two traditions in one modest structure makes it genuinely unusual.

The wall survives best along the northern and north-eastern arc, where it still stands to around one and a half metres. On the eastern side, traces of a quay remain visible, suggesting the island was regularly accessed by boat and that landings were made in an organised way rather than by clambering over the stonework. The western interior has fared worse. Wave action has eroded that portion steadily over time and it now sits permanently flooded, while the eastern half has been colonised by vegetation. References to the site appear in sources from the late nineteenth century onward, including a note by Layard from 1897 and a mention by Killanin in 1954, suggesting it has attracted intermittent scholarly attention for well over a century without ever receiving sustained study.

The island is small enough that its full extent can be taken in quickly, but the detail rewards a closer look from a boat. The dry stone construction, the remnant quay, and the contrast between the flooded western end and the overgrown eastern portion together sketch out a site that has been quietly losing ground to the lake for generations.