Tupaia's chart.

01 · The chart

Seventy-four islands
from memory.

On the voyage Tupaia drew, or dictated to Cook and others, a chart of the islands he knew: seventy-four of them in the surviving copies, spanning more than four thousand kilometres from the Marquesas to the Australs and west to Samoa and Fiji. He had visited some and knew the rest from the voyaging traditions. Cook was impressed enough to copy it, and baffled by it: the islands did not sit where European geography expected them.

For two centuries the chart was read as a muddle. In 2019 two researchers, Lars Eckstein and Anja Schwarz, published a new reading: the chart is not a map on a European grid but a navigator's diagram, organised around the bearings of islands from a starting point and the direction of the wind and swell used to reach them, with north marked as the direction of a voyage rather than a fixed point. Read that way, most of the islands fall into place.

02 · The proof, two centuries later

Hokule'a, 1976.

The question Tupaia's chart raised, whether Polynesians had settled the Pacific deliberately, was argued until 1976, when the reconstructed voyaging canoe Hokule'a sailed from Hawai'i to Tahiti without instruments, navigated by Mau Piailug of Satawal. It took about a month. The Raiatean navigator's knowledge had been real, and it was still teachable.