Between March and May 1966, contractor Aero Service Ltd recorded an offshore aeromagnetic survey over the Great Australian Bight for Outback Oil Co NL and Shell Development Australia, who are the licence holders of offshore petroleum exploration tenements OEL 33 and OEL 38 respectively. Some 16,000 line km were flown at a height of 500 m (1500 feet) above sea level on traverses 7 miles apart. This was the first regional geophysical survey conducted in the area, and had been designed with the prime objective of mapping magnetic basement and hence providing basic evidence of an indicative volume of potentially oil-productive sediments. Allowing for the reconnaissance nature of the survey, it was still deemed successful in defining an offshore extension of the Eucla Basin, the Polda Trough, and basement depths in excess of 6 km further offshore, as well as several anticlinal trends all warranting further exploration.