The Deepwater Horizon oil spill presented an unprecedented threat to the Gulf of Mexico coastline and living marine resources, and possibly to that of the southeastern USA. Needed for mitigation efforts and to guide scientific investigations was a system for tracking the oil, both at the surface and at depth. We report on such system, implemented immediately upon spill onset, by marshaling numerical model and satellite remote sensing resources available from existing coastal ocean observing activities. Surface oil locations inferred from satellite imagery were used to initialize the positions of the virtual particles in an ensemble of trajectory models, and the particles were tracked using forecast surface currents, with new particles added to simulate the continual release of oil from the well. Three dimensional subsurface tracking were also performed from the well site location at several different depths. Timely trajectory forecasts were used to plan scientific surveys and other spill response activities.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.