This volume lays the physical and conceptual groundwork for the Pacific World series, exploring both the constraints imposed and the opportunities offered to humanity by the physical environment of the Pacific region. Organized from the perspectives of "Big History" and macro-geography, the volume presents a series of major studies and surveys by authors from a range of disciplines. It opens with perspectives on the ocean, and closes with questions of human settlement, diffusion, and trans-Pacific contacts. Geologists write of the origins of the Pacific, its geological structure, and the problem of tsunamis; climatologists and oceanographers discuss the El Niño Southern Oscillation and the ocean waters; biologists and biogeographers find patterns in the life of the Basin - as is shown, all these have their impact on the potential of the region for human use and settlement. Finally, geographers, anthropologists, and archaeologists deal with the peopling of the Pacific islands, the settlement of the Americas, and the incidence and importance of pre-modern links across the Pacific.