An experimental basis is provided for the theoretical expressions associated with theE&rgr;lateral‐wave field due to a horizontal dipole in a conducting half‐space of sea water. Both perturbed and unperturbed fields are studied in detail in a laboratory model of the lithosphere. It is found that rectilinear and wedge‐shaped discontinuities at the air‐water interface comprise effective perturbations ofE&rgr;, while submerged metallic cylinders do not. The effective perturbations, localized in their effect on the overall propagation of the lateral wave over several wavelengths, have geometries chosen to characterize the broad plateaus and mountains of a real lithosphere.