The written narrative of his journey comes from the immram Navigatio Sancti Brendani Abbatis (Voyage of Saint Brendan the Abbot).

[2] Unfortunately, the versions of the Vita and the Navigatio provide little reliable information of his life and travels; they do, however, attest to the development of devotion to him in the centuries after his death.

The earliest surviving copies are no earlier than the end of the twelfth century, but scholars suggest that a version of the Vita was composed before AD 1000.

[3] Aengus the Culdee, in his Litany, composed in the end of the eighth century, invoked "the sixty who accompanied St. Brendan in his quest for the Land of Promise".

[2] Any attempt to reconstruct the facts of the life of Brendan or to understand the nature of his legend must be based principally on Irish annals and genealogies and on the various versions of the Vita Brendani.

[5] He was born among the Altraige, an Irish clan originally centred around Tralee Bay, to parents called Finnlug and Cara.

He was baptised at Tubrid, near Ardfert, by Erc of Slane,[6] and was originally to be called Mobhí but signs and portents attending his birth and baptism led to him being christened Broen-finn or 'fair-drop'.

Between AD 512 and 530 Brendan built monastic cells at Ardfert, and Shanakeel (Seana Cill, usually translated as the "Old Church"), at the foot of Mount Brandon.

The earliest extant version of the Navigatio Sancti Brendani Abbatis (Voyage of Saint Brendan the Abbot) was recorded c. AD 900.

On the Kerry coast, Brendan built a currach-like boat of wattle, covered it with hides tanned in oak bark and softened with butter, and set up a mast and a sail.

Before departing, Brendan and the monks fast at three-day intervals for forty nights and set out on the voyage that was described to him by Barinthus.

Some of the immrams involved the search for, and visits to, Tír na nÓg, an island far to the west, beyond the edges of the world map.

In the Navigatio, this style of storytelling accorded with a religious ascetic tradition in which Irish monks travelled alone in boats, in a similar way to that in which their desert brothers isolated themselves in caves.

Like an immram, the Navigatio tells the story of Brendan, who, with some companion monks, sets out to find the terra repromissionis sanctorum, ("Promised Land of the Saints"), that is, the Earthly Paradise.

[15] Jude S. Mackley holds that efforts to identify possible, actual locations referred to in the Navigatio distract from the author's purpose of presenting a legend of "salvation, monastic obedience and the faith required to undertake such a pilgrimage.

In its use of octosyllabic couplets to recount a quest narrative drawn from Celtic sources, it has been described as a precursor of later Old French romances.

Belief in the existence of Saint Brendan's Island was almost completely abandoned until a new theory arose that the Irish were the first Europeans to encounter the Americas.

[24] Maps of Christopher Columbus' time often included an island denominated Saint Brendan's Isle that was placed in the western Atlantic Ocean.

[25] Brendan travelled to Wales and the holy island of Iona, off the west coast of Scotland; returning to Ireland, he founded a monastery in Annaghdown, where he spent the rest of his life.

[8] Having established the bishopric of Ardfert, Brendan proceeded to Thomond, and founded a monastery at Inis-da-druim (currently Coney Island), in the present parish of Killadysert, County Clare, c. AD 550.

He then journeyed to Wales and studied under Gildas at Llancarfan, and thence to Iona, for he is said to have left traces of his apostolic zeal at Kil-brandon (near Oban) and Kil-brennan Sound.

After a mission of three years in Britain he returned to Ireland, and evangelized further in various parts of Leinster, especially at Dysart, County Kilkenny, Killeney near Durrow (Tubberboe Irish: Tóbar Bó, meaning 'Well of the cow'),[27] and Brandon Hill.

Fearing that after his death his devotees might take his remains as relics, Brendan had previously arranged to have his body secretly returned to the monastery he founded in Clonfert, concealed in a luggage cart.

Religious houses were formed at Gallerus, Kilmalchedor, Brandon Hill, and the Blasket Islands, to meet the wants of those who came for spiritual guidance from Brendan.

At the United States Naval Academy in Annapolis, Maryland, a large stained glass window commemorates Brendan's achievements.

He is also a patron saint of boatmen, mariners, travellers, elderly adventurers, whales,[28] the United States Navy,[29] and also of portaging canoes.

The ruins of the ancient Cathedral of St Brendan, and of its annexed chantries and detached chapels, form a very complete reliquary of Irish ecclesiastical architecture, in its various orders and ages, from the plain but solid Danhliag of the seventh or eighth century to some late and most ornate examples of medieval Gothic.

In the Sicilian town of Brontë there is a church dedicated to Saint Brendan, whose name in the local dialect is "San Brandanu".