  We present results from an experiment designed to better understand the
mechanism by which ocean currents and winds control flotsam drift. The
experiment consisted in deploying in the Florida Current and subsequently
satellite tracking specially designed drifting buoys of varied sizes,
buoyancies, and shapes. We explain the differences in the trajectories
described by the special drifters as a result of their inertia, primarily
buoyancy, which constrains the ability of the drifters to adapt their
velocities to instantaneous changes in the ocean current and wind that define
the carrying flow field. Our explanation of the observed behavior follows from
the application of a recently proposed Maxey--Riley theory for the motion of
finite-size particles floating at the surface ocean. The nature of the carrying
flow and the domain of validity of the theory are clarified, and a closure
proposal is made to fully determine its parameters in terms of the carrying
fluid system properties and inertial particle characteristics.
