Among its features is Tobermurry, a holy well, a type of site found across Ireland where a natural spring becomes associated with a saint or with curative and spiritual properties, drawing pilgrims who might leave votive offerings, pray at nearby stones or crosses, or complete a prescribed circuit known as a pattern. These sites often sit at the intersection of pre-Christian water veneration and later Catholic devotion, and many remain active places of pilgrimage to this day.

Caher Island itself has long been recognised as a place of religious significance, associated with early Christian monasticism and with the pilgrimage traditions of the west of Ireland. The island is one of the stations on a traditional pilgrimage route connected to the wider devotion to Saint Patrick in the region, most famously expressed at nearby Croagh Patrick on the mainland. Wells bearing the name Tobermurry, which derives from the Irish tobar Muire, meaning the well of Mary, are found in various parts of Ireland, and their dedication to the Virgin Mary reflects the deep embedding of Marian devotion in Irish popular religious practice.