Tupaia’s Map is one of the most famous and enigmatic artefacts to emerge from the early encounters between Europeans and Pacific Islanders. It was drawn by Tupaia, an arioi priest, chiefly advisor and master navigator from Ra‘iātea in the Leeward Society Islands in collaboration with various members of the crew of James Cook’s Endeavour, in two distinct moments of mapmaking and three draft stages between August 1769 and February 1770. To this day, the identity of many islands on the chart, and the logic of their arrangement have posed a riddle to researchers. Drawing in part on archival material hitherto overlooked, in this long essay we propose a new understanding of the chart’s cartographic logic, offer a detailed reconstruction of its genesis, and thus for the first time present a comprehensive reading of Tupaia’s Map. The chart not only underscores the extent and mastery of Polynesian navigation, it is also a remarkable feat of translation between two very different wayfinding systems and their respective representational models.