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Thispaper describes a geophysical and geotechnical site survey for the Heritage Platform to assess jacket levelness and water depth. Data were obtained from deep-tow seismic and cone penetrometer equipment which were positioned wi thin the survey area through the use of an on-bottom network of medium frequency acoustic transponders.This allowed the high degree of seafloor mapping accuracy to be carried through to jacket placement.Upon set-down, the jacket was found to be well within the required levelness tolerance and in a water depth within one foot of the design specifications. This application demonstrates the accuracy with which the methods described in the paper can characterize the seafloor for engineering applications. SICILIANO, NORDIN, IRICK, GRUNDMEIER AND TAYLOR the clay were confined to a zone about one foot above the clay/sand interface.