Transports in fluids can be approached from two complementary perspectives. In the
Eulerian view of mixing, the focus is on the concentration field. In the Langrangian view, fluid
parcels are followed around as they move with the flow, experiencing chaotic or stochastic
motion. This book examines both pictures, presenting a number of theoretical and
experimental lectures on various aspects of transport and mixing of active and passive
particles in geophysical flows.