Most visitors focus on the corbelled beehive huts and the vertiginous stone stairways, but the monks who lived here also solved a more mundane problem with quiet ingenuity: where to find fresh water on a salt-lashed island with no natural springs to speak of. Tucked into the fabric of the settlement are small cisterns, recesses cut or built to collect and hold rainwater, easy to miss against the rough stonework around them.

One such cistern sits at the base of the platform supporting clochaun E, one of the distinctive dry-stone beehive huts (a clochaun is a corbelled circular dwelling, built without mortar, the courses of stone overlapping inward until they meet at the top) that formed the living quarters of the community. Recorded in detail by O'Sullivan and Sheehan in 1996, the opening of this particular recess measures 0.4 metres wide and 0.35 metres high, roughly the dimensions of a large letterbox. It closely resembles a second cistern elsewhere in the complex, suggesting a degree of deliberate, repeated design rather than improvisation. The monks who occupied Skellig Michael from around the sixth century onwards were solving an engineering problem that every inhabitant of a treeless ocean rock must face, and these small apertures are part of that solution, as considered in their way as the great stairways cut into the cliff.