The small medieval church of St. Caomhán, the patron saint of Inis Oirr, sits in a hollow that the islanders have to dig out from sand and grass once a year to keep it accessible. The oldest parts go back to the 10th century; the nave and chancel arch are 14th-century work. Caomhán's grave, marked by a stone slab, lies inside what is left of the chancel.
The annual cleaning happens around the saint's feast day on 14 June, when the islanders gather to shovel back the sand that has crept down the dunes over the previous twelve months. At any other time of year the church sits low, with its roofless walls just reaching the level of the surrounding ground — a small, quiet place that feels much older than its dates suggest. Walk down from the road behind the strand; there is no formal path, just a worn track through the dunes.