Brendan the Navigator was an lrish priest who lived in the 6th century. He is most famous for embarking on a voyage in search of the mythical "Island of the Blessed." The details of Brendan's voyage, recorded as stories in old manuscripts, suggest to some that Brendan and his crew reached North America during their voyage, becoming the first Europeans to do so. Those who advance this theory support it with several arguments.

First, the written stories about Brendan's voyage seem to make references to places his crew would have visited on the way to North America. Sailors in Brendan's time typically traveled from island to island to avoid the dangers of long periods on the open seas. A journey from Ireland to North America would have taken Brendan to the Faroe Islands, Iceland, and Greenland before reaching the North American continent (see illustration). Places described in the stories about Brendan's voyage share characteristics with some of those island locations.
 

Second, a team of researchers recently constructed a boat resembling a curragh, an old Irish boat of the type used by Brendan. Curraghs had a wooden frame with cowhides stretched over it. In building the boat, the researchers used only materials and techniques available in Brendan's time. The researchers were able to sail this boat from Ireland to North America, demonstrating that boat technology in Brendan's time was sufficient for a journey across the Atlantic Ocean.

Third, old markings that may have a connection to Brendan's voyage have been discovered at several locations in North America. Cut into rocks, these markings consist of narrow vertical lines resembling letters of ogham, an old Irish alphabet in frequent use in Brendan's time. The resemblance of those marks to ogham has convinced some that the markings were made by members of Brendan's crew.