It is easy to miss, and that is rather the point. What looks like a faint disturbance in the lake is in fact a constructed structure, a circular cairn roughly fifteen metres in diameter and two metres high, built from medium to small stones and resting on sandy lake marl. At present water levels it clears the surface by approximately ten centimetres. Technically above water, practically invisible.

A crannog is an artificial or partially artificial island, built in Irish and Scottish lakes and rivers from the Bronze Age through to the early modern period, typically as a defended dwelling place. This particular example, catalogued as Dysart Island 2, sits in roughly 1.6 metres of water. Researcher Aidan O'Sullivan, writing in 2004, noted its distinctiveness within the broader category: a level surface, an even profile, steep sides that drop sharply into the lake, and a position well out in open, deep water rather than tucked into the shallows near shore. Most crannogs hug the margins; this one sits exposed and isolated, which makes its construction all the more deliberate. Who built it, and when, is not recorded, but the effort required to pile and shape stone in open lake water speaks to a serious and considered purpose.