That modest footprint, barely larger than a suburban garden, is almost certainly not natural. This is a crannog, an artificial or artificially enlarged island, typically constructed from layers of peat, brushwood, timber, and stone, used as a dwelling site from the early medieval period onwards and sometimes as late as the seventeenth century. The isolation was the point: a body of water between you and the mainland offered a meaningful degree of security at a time when it mattered considerably.

What makes this particular crannog quietly curious is the gap in its cartographic record. When the Ordnance Survey mapped Ireland in 1836, and again when surveyors returned in 1876, the island went unrecorded. It appears for the first time on the 1912 edition of the OS maps. Whether it was simply overlooked in the earlier surveys, obscured by water levels or vegetation, or whether the island became more visible over the intervening decades is not clear. Crannogs can be difficult to read from a distance, especially when overgrown, and the nineteenth-century surveys, thorough as they were, did not catch everything. The island sits in Killyvaghan Lough, and its subtriangular outline, oriented roughly north-north-west to south-south-east, is the kind of detail that rewards a careful look at a large-scale map before visiting the loughside.