The question of the extent of Gaelic influence on medieval Icelandic literature and culture has fascinated scholars for many years, especially the possible relationship between Irish voyage literature and Icelandic narratives concerning journeys to the Otherworld. This book provides a fresh examination and reappraisal of the topic. It compares the Irish immrama ‘voyages', including the greatly influential Hiberno-Latin text Navigatio Sancti Brendani ‘The Voyage of Saint Brendan', and echtrai ‘otherworld adventures'with the Icelandic fornaldarsögur and related material, such as the voyages of Torkillus in Saxo's Gesta Danorum. It also assesses stories about Hvítramannaland, touches on similarities in folk narratives and examines the influence of Classical and Christian literature on the tales. In conclusion, the book makes proposals to account for the parallels and differences between the two traditions and is accompanied by an extensive bibliography and several indices.