A crannog is an artificial, or partly artificial, island dwelling, typically built from layers of timber, peat, brushwood, and stone, and used across Ireland and Scotland from the Bronze Age through to as late as the seventeenth century. They were built in lakes and wetlands, sometimes as permanent settlements and sometimes as refuges, and their island character was the point: water was a defensive barrier, a moat that cost nothing to maintain. The name Islandmore, meaning roughly "big island" in its Anglicised form, suggests a feature prominent enough to have lodged itself in local geography, though whether the crannog itself is what earned the place its name is not recorded.

Beyond the classification and location, the documentary record for this particular site is presently sparse. What can be said is that it sits within a county whose lakelands and river basins made it hospitable to exactly this kind of settlement, and Clare has no shortage of such sites scattered across its interior waters. Crannogs in the region were often associated with early medieval Gaelic families, serving as the fortified homes of local lords or as places where cattle and valuables could be secured during periods of raiding. The physical remains of a crannog, when visible at all, typically appear as a low, rounded islet, sometimes with traces of structural timber preserved in the waterlogged conditions beneath, which can make them extraordinarily useful to archaeologists working on questions of diet, craftsmanship, and daily life in early medieval Ireland.