That Cook respected and trusted Tupaia is evidenced by the fact that for an entire month, he let Tupaia navigate his precious ship through the archipelago of the Society Islands, and on southward across open waters to Rurutu in the Austral Group. Tupaia turned out to be an invaluable linguistic and cultural translator for the crew, especially so in Aotearoa/New Zealand, where Cook landed next. Only when the Endeavour reached Australia did Tupaia’s powers to communicate fail; he eventually fell ill and tragically died in Batavia, today’s Jakarta in Indonesia.

Only copies remain, and they’re hard to comprehend:

For almost 250 years, Tupaia’s Map posed a riddle to historians, anthropologists and geographers of the Pacific alike. Until more recently, only a rather small number of islands on the map could be reliably identified. The British on Cook’s ship knew little Tahitian, and their linguistic talent was limited. They wrote down what they heard Tupaia say when he named the islands he drew, in an often very corrupted English transcription. What is more, many of the Tahitian island names are no longer in use in the region. But the more foundational problem is that even those islands which could be identified are hardly where one would expect them according to the logic of a Western map. By the standards of maps in Mercator projection as Cook used and drew them, the islands seem to be all over the place: Islands thousands of kilometers apart appear right next to each other, islands which should be to the south of Tahiti appear in the northern quadrants, small islands can have very large outlines, etc.