Islanders paddle for miles in a ceremonial gift loop that never actually stops moving

Across a ring of islands near Papua New Guinea, the Kula exchange circulates two kinds of ceremonial valuables endlessly: red shell necklaces travel one direction around the ring, white shell armbands the other. No one keeps a valuable for long or trades it for anything practical; the entire dangerous, canoe-borne exchange exists purely to build trust, status, and alliance between distant trading partners.

— Bronisław Malinowski, Argonauts of the Western Pacific — Routledge & Kegan Paul, 1922