It measures about 56 metres east to west and 42 metres north to south, rising less than one and a half metres above the lake bed, its surface fairly level and covered in blackened, shattered stones. Scattered across it are low, roughly circular piles of similar material, each a couple of metres across. The question that lingers is whether this is a crannog at all. A crannog is an artificial or heavily modified island, typically built up from timber, brush, and stone during the early medieval period to provide a defended or secluded dwelling place, but the size and surface character of this particular island leave open the possibility that it is entirely natural, with no human construction involved beyond the causeway that leads to it.

That causeway is where the human hand becomes unmistakable. It connects the island to the peninsula at its north-eastern end and was built in three distinct sections, each using a different technique. The section closest to the island, just four metres long and two metres wide, uses large rounded stones forming a frame packed with smaller material. The middle section, ten metres in length, is a thin line of subangular stones laid side by side. The outermost section, nearest the shore and the longest at twelve metres, is made of densely packed stones throughout. The variation in construction across these three sections hints at either different phases of work, different available materials, or different practical demands at each point along the crossing. No dates have been established for the causeway's construction, and the island itself has not been excavated.