One is called Friar's Island, the other Abbey Island, but on the 1838 Ordnance Survey six-inch map those names are the wrong way around. By the time the survey was revised in 1947 and 1948, the labels had been switched. The discrepancy is not merely a curiosity of mapmaking; it points to a religious site whose physical remains have all but vanished, leaving only a name and a local memory to mark where something once stood.

According to local tradition, a church formerly occupied what is now called Friar's Island, the smaller of the two, lying about 240 metres offshore and to the north-north-east of Cloonmoylan House. At some point the building was demolished and its stones carted away, reportedly to construct a mill situated just over three kilometres to the north. The island itself has not fared well in the intervening years. Rising water levels in the lake have gradually eaten into its margins, reducing it to a roughly circular patch of ground about fifteen metres across, now heavily overgrown. No structural traces survive above the surface; whatever walls or foundations might remain are buried beneath vegetation and sediment, and beneath the lake itself.

The pairing of names, Friar's Island and Abbey Island in such close proximity, suggests this corner of Lough Derg once had a more concentrated ecclesiastical character than the current landscape lets on. Whether the two islands functioned together, or whether one name simply migrated across the water through generations of oral and written transmission, is no longer clear. What remains is a fifteen-metre scrap of land, a reversed label on an old map, and the account of a church broken up to serve a mill.