Known as Gosling Island, it measures roughly fifteen metres across, elongated and irregular in outline, and at its centre sits a cairn of large angular blocks, five to ten metres in diameter, which may have been deliberately quarried and placed there. The question of whether this is a natural rocky outcrop that humans gradually shaped to their purposes, or a purpose-built crannog that simply used the bedrock as its foundation, remains genuinely open.

A crannog, for the unfamiliar, is an artificial or partly artificial island, typically constructed during the early medieval period in Ireland and Scotland as a defended dwelling place, often for a family of high status. What makes Gosling Island quietly complicated is that it seems to sit at the boundary between the natural and the man-made. As archaeologist Aidan O'Sullivan noted in 2004, it is a probable natural island that may have been enhanced for use as a crannog, rather than one built from scratch in open water. The sloping profile, the rocky outcrops clustered particularly to the east, and the cairn sitting atop the bedrock all suggest a place that people recognised as useful and then modified, rather than one they conjured from nothing. The broader setting of Rochfort Bay adds further texture; O'Sullivan also recorded small crannogs and rock platforms scattered around the bay, suggesting this part of Lough Ennell saw sustained, if modest, human activity across time.