There is no island beneath it, or at least none that a passing eye would register. What the tree is actually rooted in sits 1.3 metres below the surface: a submerged crannog, an artificial island constructed from stone, built by human hands at some point in the past and now quietly drowned beneath the lake.

A crannog, for those unfamiliar with the term, is a man-made island, typically built out into a lake or wetland as a defensible or otherwise advantageous place to live. They were constructed across Ireland and Scotland over a very long span of time, from the Bronze Age through to the early modern period, and they were usually built from timber, stone, peat, and other available material piled and packed into place. This particular example is the most north-easterly of a cluster of three small reefs running in a north-east to south-west alignment across the south-east sector of the lake, collectively named Stone Islands South on Ordnance Survey maps from as early as 1838 and still recorded under that name on the 1929 revision. It measures roughly 16.7 metres east to west and 12.5 metres north to south, a modest footprint, and its stonework is consistent in character with other crannogs identified elsewhere in Lough Rea, suggesting a shared tradition of construction across the lake. That the structure has sunk below the waterline, or that the lake level has risen around it, is in itself unremarkable for crannogs in Ireland, where fluctuating water levels over centuries have obscured many such sites entirely. What is unusual here is that one tree has managed to survive, rooted in the submerged stone, marking the spot with quiet persistence.