Caher Island, no more than 128 acres, is an uninhabited little island situated between Clare Island and Inishturk six miles southwest of Roonagh Pie.

In Irish it is called “Chathair na Naomh” or “Cathair Phadraic” meaning “The isle of saints” or “St Patrick's isle”.

It is reputed to have been a holy place and the site of a monastic settlement and regarded as St Patrick’s farthest west excursion. The Saint visited the island and spent some time there after his fast on top of Croagh Patrick.

There are three sites named after Patrick: a circular stone fort, a church within a circular cashel and a flat stone just outside the church door named "Leaba Phádraic" or “St Patrick’s Bed”; the altar stones in the church were thought to be holy and have special powers. It was said the pumice one could raise a violent storm if removed.

It has the ruins of an Early Christian monastery, dating back around the 6th and 7th centuries AD, a primitive chapel in an enclosure, a series of decorated cross and inscribed stones. The island seems to have been the hermitage site of a small community of monks, perhaps followers of St Columba, in 7th century. After Saint Patrick’s sojourn the community increased and an Abbot was appointed.

The famous Pirate Queen Grace O’Malley landed on Caher Island to capture a MacMahon follower who killed her Spanish lover.

Among Clare fishermen the island is reputed to be one of the holiest islands of Connaught along with Inishglora (Mayo) and Macdara (Galway) and in the past sailors used to lower their sails and send a little prayers sailing closer to its shoreline.

The pilgrimage to Croagh Patrick on the last Sunday in July originally included the performance of the Stations of the Cross at both Caher Island and Kilgeever.

On 15th of August each year there is a pilgrimage to the island.

The island is accessed by boat from Inishturk.