A crannog is an artificial or semi-artificial island, typically constructed from layers of peat, timber, brush, and stone, and used as a defended dwelling from the Bronze Age through to as late as the seventeenth century in some parts of Ireland. They are found across the country in considerable numbers, and yet each one represents a particular act of engineering and a particular community's decision to put open water between themselves and the rest of the world.

The Clare crannog in Mayo sits within a broader landscape that has long rewarded those who look carefully at its lakes and low ground. Mayo contains dozens of recorded crannogs, many of them still unexcavated and understood only in outline. Without detailed field investigation, it is rarely possible to say with confidence when a given crannog was first constructed, who built it, or through what periods it remained in use. What can generally be said is that crannogs in the west of Ireland often show evidence of occupation spanning several centuries, with timber structures, wooden artefacts, and occasionally metalwork surviving in the waterlogged conditions that would destroy them anywhere on dry land.