Among the remains there is a cross-slab, a type of monument common to the early medieval period in Ireland, typically a flat stone incised with a cross rather than carved in the round. These slabs often marked graves or served as focal points for prayer within monastic enclosures, and Caher Island has a concentration of them that speaks to a community once serious about its devotional life in an exposed and unforgiving place.

The island, known in Irish as Cathair na Naomh, the city or stone fort of the saints, is traditionally associated with Saint Patrick, who is said to have spent time there before his legendary vigil on Croagh Patrick on the mainland. Whether or not that association holds historical weight, the physical evidence of early Christian activity is substantial. The remains include a small oratory, enclosure walls, and multiple cross-slabs, suggesting the site functioned as a genuine place of pilgrimage and monastic retreat, probably from somewhere in the early medieval centuries. The Atlantic setting, brutal in winter and isolating year-round, was not incidental; early Irish monks frequently sought out marginal, difficult places as an expression of ascetic commitment.

Caher Island is accessible only by boat, and crossings depend entirely on sea conditions, which in Clew Bay can change quickly. The island is uninhabited and there are no facilities. Pilgrims still visit on the last Sunday of July, Garland Sunday, as part of a pattern that connects the site to the wider tradition of Reek Sunday on Croagh Patrick. The cross-slabs themselves sit within the monastic enclosure, and their incised markings, worn but legible in reasonable light, reward a slow and attentive look.