The Goodnews Bay concentrically zoned Ultramafic complex has produced onshore placer platinum deposits, and more than 650,000 tr oz of platinum-group metals (PGM) have been recovered since 1926. It is generally suspected that placer PGM also occur in the adjacent marine environment; however, no deposits have yet been delineated. Magnetic surveys and sea-floor sediment sampling begun in 1985 show that the complex is a large, south-dipping, lensoidal body that extends offshore to 5 km. The present seafloor was an emergent foreland as recently as 8,000 yr ago. High-energy ocean processes are presently transporting and depositing sediment such that PGM- bearing alluvial and marine sediments are reworked and later masked by barren littoral drift of glacial origin. Exploration targets include (1) placers formed since present transgression began and (2) ancient marine and drowned fluvial deposits.