Great Ireland (Old Norse: Írland hit mikla or Írland it mikla), also known as White Men's Land (Hvítramannaland) or Land of the White People, and in Latin similarly as Hibernia Major and Albania, was a land said by various Norsemen to be located near Vinland. In one report, in the Saga of Eric the Red, some skrælingar captured in Markland described the people in what was supposedly White Men's Land, to have been "dressed in white garments, uttered loud cries, bore long poles, and wore fringes." Another report identifies it with the Albani people, with "hair and skin as white as snow."

Scholars and writers disagree on the nature of the land, from either being treated as a myth based on faded knowledge of lands in the western ocean, to theories on actually locating it somewhere in North America.

Celtic folklore tells of a mythical land across the western ocean often referred to as the Celtic Otherworld, also known as Annwn or Avalon, among other names. The Byzantine scholar Procopius of Caesarea described the Otherworld of the ancient Gauls and said it was located west of Britain.

Plutarch (1st cent.), in a chapter from the Moralia called 'Concerning the Face Which Appears in the Orb of the Moon', describes a land called Ogygia that was five days sail from Britain and that the Celtic natives also knew of three other lands equal distance from Ogygia and from each other in the direction of the setting sun including a 'Great Continent' and 'Land of Cronus' and from the ancient era until the early Christian historical era, geographers referred to the waters beyond Iceland as the ‘Cronian Sea’.

Irish documents called ‘Immrama’ from the 6th and 7th centuries supposedly record the adventures of Irish priests in the western ocean, while other folkloric stories tell of the Atlantic voyages of Saint Brendan and King Arthur, often considered mythical. Gerardus Mercator refers to a Jacob Cnoyen, who had learned that eight men returned to Norway from an expedition to the Arctic islands in 1364, in a letter to John Dee (1577), stating specifically that the eight men who came to Norway in 1364 were not survivors of a recent expedition, but descended from the colonists who had settled the distant lands several generations earlier and claimed to be descendants of King Arthur's expedition.

The following is a translation taken from Mercator's 1569 polar map:

"we have taken [the Arctic geography] from the Itinerium of Jacobus Cnoyen of the Hague, who makes some citations from the Gesta of Arthur of Britain; however, the greater and most important part he learned from a certain priest at the court of the king of Norway in 1364. He was descended in the fifth generation from those whom Arthur had sent to inhabit these lands, and he related that in the year 1360 a certain Minorite, an Englishman from Oxford, a mathematician, went to those islands; and leaving them, advanced still farther by magic arts and mapped out all and measured them by an astrolabe in practically the subjoined figure, as we have learned from Jacobus. The four canals there pictured he said flow with such current to the inner whirlpool, that if vessels once enter they cannot be driven back by wind."

According to the Landnámabók, Ari Marsson discovered the land six days' sailing west of Ireland. This journey is thought to have occurred around the year 983.