Florida Sportsman reported that, "Data shows movement of subsurface oil is consistent with ocean currents... movements are generally consistent with observed ocean currents in the area."
From the NOAA website, Physical Oceanographic Division, Monitoring the Gulf of Mexico Conditions During the Deepwater Horizon Oil Spill:
Numerical simulations of flow trajectories show how the ocean currents spread idealized particles released from a given location. These simulations are based on satellite observations or numerical simulations of ocean surface currents. The spreading of these idealized particles approximates that of oil, below the ocean surface, where the effect of wind and sunlight are not that important compared with the surface where discrepancies between these simulations and the spreading of oil are possible.
[This map for July] shows an animation of the evolution of SURFACE water particles (in black) released daily since April 20 at the Deepwater Horizon location... Red tones indicate attracting... barriers for the moving particles... particles closely follow [these red tones.]
At a depth of 200 meters (does not show underwater currents near
coastline because depth under 200m):
At a depth of 700 meters: