Periodic features observed on the ocean surface from the Earth Resources Technology Satellite 1 have been interpreted as surface slicks due to internal wave packets. They appear to be generated at the edge of the continental shelf by semidurnal and diurnal tidal actions and propagate shoreward. Nonlinear effects apparently distort the wave packets as they progress across the shelf. This observational technique constitutes a new tool for delineating two dimensions of the internal wave field under certain limited conditions.