The book surveys medieval and early-modern accounts and maps to trace how legend, exploration, and cartography combined to produce reports of Atlantic islands. It treats Atlantis, the voyages of St. Brendan, the island of Brazil, the Isle of Seven Cities, Mayda, Greenland/Markland, Estotiland and the Zeno islands, Antillia and the Antilles, Corvo, Buss, and other phantom isles, comparing classical, Norse, and Iberian traditions and reproductions on medieval charts. The author evaluates sources, map evidence, and interpretive errors to show how imagination and navigational reports shaped geographic belief about the Atlantic.