Ship-borne site investigations of four proposed offshore drilling locations at approximately 90 miles south-west of Port Lincoln, in water depths of about 500 feet, included a sparker seismic survey, an echo sounder survey, drop sampling and seabed coring. Poor anchoring conditions were indicated, with evidence obtained of a relatively thin overburden consisting of variably layered, alternating hard and soft bottom sediments overlying very hard and flat-lying bedrock. Operational difficulties with seabed core drilling also suggest that in addition to hostile wind, wave and swell conditions, strong tidal currents accentuated by close proximity to the edge of the continental shelf will have an appreciable and possibly dangerous effect on anchor loading. All four sites possess seabed conditions which are unsuitable for the safe use of a conventional anchor-type mooring system commonly used with a semi-submersible drilling platform. Three alternative but hitherto largely untried anchoring techniques are suggested.