The course of civilization is carved in ocean currents. Where sea layers mix, where rains travel or wastelands spread, where great upwellings bring deep, cold, nutrient-rich waters to the energy-bathed surface and fish go mad with fecundity, where soils turn fertile or anemic, where temperatures turn habitable or harsh, where trade routes flourish or fail: all this the global ocean engine determines. The fate of continents is written in water. And sometimes great cities owe their existence to tiny ocean islands.
