During the Deepwater Horizon (DWH) oil spill, extensive areas of the Gulf of Mexico (GoM) were closed for fishing due to the risk of seafood contamination and fishers’ health. The closures were determined daily according to the estimated extent of the spill relying mainly on satellite imaging. These closures were largely limited to the northern GoM. Yet, evidence from the field indicates a presence of oil beyond the closures, in some cases at toxic concentrations. With the advancement of oil transport modeling, together with the availability of new in situ data, we examine the 4D extent of the DWH spill, along with the effectiveness of the fishery closures in capturing the oil spill extent. We use the oil application of the Connectivity Modeling System (oil-CMS), cross-checked against in situ BP Gulf Science Data (GSD) and other published studies. The oil-CMS indicates that DWH extended well beyond the satellite footprint and fishery closures, with the closures capturing only ~55% of the total extent of the spill. With an increasing global shift toward deep-sea drilling, our findings are important for the safety of coastal communities and marine ecosystems around deep-sea drilling areas.