As the Mediterranean shaped the classical world, and the Atlantic connected Europe to the New World, the Pacific Ocean defines our tomorrow. With China on the rise, so, too, are the American cities of the West coast. Today, the Pacific is ascendant. Its geological history has long transformed us --- tremendous earthquakes, volcanoes and tsunamis --- but its human history, from a Western perspective, is quite young, beginning with Magellan’s 16th-century circumnavigation. It is a natural wonder whose most fascinating history is currently being made.