Which people navigated the Pacific using stick charts of swell patterns?

The Marshallese, whose charts are lattices of palm rib bound with fibre, with shells for islands - and the sticks map the water rather than the sea floor. They record how ocean swells bend around and between islands, where two swell trains cross, and where the pattern tells you land is near before you can see it.

They were memory aids for the navigator alone, not charts to carry aboard. A navigator learned one, internalised the pattern, and left it at home; the knowledge was closely held within families and taught by lying in the bottom of a canoe to feel the interference of swells through the hull.

Instrument-free navigation of this kind was long dismissed as impossible by Europeans, which is how the drift theory of Pacific settlement survived so long. The 1976 voyage of the Hokule'a from Hawaii to Tahiti, navigated by Mau Piailug of Satawal using stars, swell and birds, settled it in practice - and Mau then broke with custom to teach outsiders, on the grounds that the tradition would otherwise die with him.