On Mangaia, the oldest and most southerly island in the Cook Islands, Pwo Grand Master Navigator Peia Patai sails a recreated vaka moana using the non-instrument wayfinding he learned from stars, swells and ecological signs. Among ancient celestial maps painted in limestone caves and the reefs and gardens of the atoll, the voyage traces Ra'ui, the Polynesian practice of taking only what is needed so that the ecology survives for those who come after.