AIM: The primary aim of the 1973 Shell R 7 Marine Seismic Survey programme was to acquire further detailed coverage over several previously disclosed anticlinal leads within Duntroon Basin EPPs 6 and 7, to attempt to define suitable prospective structures for the next round of exploratory drilling required on those permits. The potentially sizeable Jerboa, Cuscus, Koala, Bandicoot, Wallaroo and Quokka (SE Corner) leads were addressed for this purpose. In addition, approximately 150 line km of tie lines were to be recorded in the deep water part of EPP 6, west of the Platypus Prospect, to allow the future correlation of the geological section known from the drilling of Platypus 1 with the seismic stratigraphic character of this area. Following a failed farmout offer over its Bight shelf area EPP 5 acreage, Shell elected also to continue alone for the time being in exploring this permit, initially by acquiring a limited amount of detailed seismic over the undrilled Potoroo and Bunyip leads. METHODS: Survey dates: 1 - 25/4/73. Energy source: Tuned airgun array. CDP coverage: 2400%. Recording mode: 48 channel digital - Texas Instruments DFS III recorder. SP interval: 50.0 metres, group interval: 50.0 metres. RESULTS: 94 reflection seismic lines totalling 1895 line km (403 km within EPP 5, 734 km within EPP 6 and 760 km within EPP 7 were acquired by the Geophysical Service International Party 931 M/V Eugene McDermott II, and processed in Sydney by GSI Party 854. Shipboard navigation and line positioning was carried out by radar using Offshore Navigation Inc.'s Shoran system. Since the geological settings of the profiled Duntroon Basin leads varied in each instance, the seismic data processing steps applied to the respective datasets needed to be separately tailored to provide optimum reflector resolution. However, despite these measures the quality of processed sections remained only poor to fair, resulting in two leads, Koala and Bandicoot, being abandoned for lack of reliable closure. The Jerboa, Cuscus and Wallaroo (East) leads were able to be structurally matured, but the discernible sealing risk was high for all three traps, thereby giving little drilling encouragement. The previously sparsely mapped Quokka lead in the southeastern corner of EPP 7 appeared the most interesting feature on the R 7 seismic, but requires further detailed seismic definition of possible Cretaceous sandstone reservoir objectives thought to exist below the base Tertiary unconformity.