We report the observation of internal wave fields evolving at the continental slope in the northern Gulf of Mexico using oil-industry three-dimensional (3D) seismic imaging techniques. High-resolution seismic images reveal dynamic wave fields actively present in the 600-900 m water column. The spectral analysis of these wave fields shows that these waves possess a slope that represents the characteristics of internal waves. Further analyses suggest that these internal wave fields are most likely generated by a nearby cyclonic eddy and its interaction with the continental slope. This work demonstrates that oil-exploration 3D seismic data, if appropriately analyzed, are a useful and powerful dataset for studying the temporal evolution of deep ocean dynamics that would otherwise be impossible at similar vertical and lateral resolution.