It is a souterrain, a type of man-made subterranean chamber or tunnel built during the early medieval period in Ireland, typically constructed from drystone walling and covered with large capstones. Their exact purposes remain debated, though they are generally understood to have served as cool storage spaces, places of refuge, or both, and they appear across Ireland in considerable numbers, often associated with ringfort settlements above ground.

The souterrain at Durless is recorded as a monument, which places it within a broader landscape of early medieval activity in the west of Ireland, a region where such features are not uncommon but rarely receive much individual attention. Mayo has its share of early Christian and pre-Norman archaeology, and underground passages of this kind were typically constructed between roughly the sixth and twelfth centuries. Beyond the fact of its existence and its location in Durless townland, the specific details of this particular structure, its dimensions, its construction, its condition, and any associated features, remain inaccessible through open channels at present.