The ocean is a sensorium: it records the transformations of the earth in its complex dynamics, and it inscribes back in the forms of life its own cycles. Today, the global ocean is rapidly changing its circulations, energies, interactions, and ecologies. It is the most dynamic and sensitive component of our living planet, yet the most unknown. The ocean is in a new phase of its non-linear history, shaped by the intensification of the impact of human activities on the earth system—the Anthropocene.