A shallow refraction seismic survey was conducted along the causeway adjacent to the boat channel at St. Kilda, during its exposure at low tide. The aim of the survey was to determine the thickness of the St. Kilda Formation consisting of shelly sand, above the Glanville Formation of calcreted shells. This information will aid in the design of a sheet pile construction at the sides of the boat channel. The interpreted seismic section generally agrees with drill information along the traverse.