Electromagnetic surface waves can propagate along boundaries between electrically different media like air and earth or sea water and rock. They have unusual properties that make them valuable tools in geophysical prospecting and diagnostics. They are not suited to deep sounding. Much of the current theory for their geophysical application has been limited to ranges of the parameters and variables that permit the use of Norton’s graphs which were developed for radio communication over the earth. A recently derived set of accurate, very general, and simple formulas for the surface‐wave fields of antennas near a boundary surface has provided an expanded horizon for understanding and using surface waves as distinct from plane waves that travel down into the earth. The new formulas are given and used to assist in the interpretation of available measurements and then applied to the determination of the average conductivity and permittivity of the part of the lithosphere very close to the sea bottom where the lateral waves travel.