The ocean is an endless wonder that has shaped the progress of civilization for all of human history. Thousands of years ago, the sea retreated and exposed more than 2 million acres of dry land, enabling early man to migrate from Asia and eventually settle North and South America. Centuries later, explorers such as Christopher Columbus and Ferdinand Magellan braved the waters as they searched for shorter ocean routes to new worlds. When, in 1800, all surface areas of the ocean had been explored, scientists turned their gaze to the deepest recesses of the sea, discovering thousands of species of plants and animals there. The sea remains our planet's largest source of food, fuel, and energy, holding the very key to life for sea creatures and people alike.