Between December 6, 1985, and January 9, 1986, the Hawaii Institute of Geophysics Research Vessel Moana Wave surveyed the Manus Basin, north of New Britain, Papua New Guinea. This basin occupies a back‐arc position with respect to the New Britain arc‐trench system and contains an active plate boundary (Figure 1; also Taylor ). Organized under the aegis of the Committee for Coordination of Joint Prospecting for Mineral Resources in South Pacific Offshore Areas (CCOP/SOPAC), the cruise was part of a program to assess the mineral potential of southwest Pacific marginal basins and included a National Science Foundation‐sponsored study of crustal accretion processes in a fastspreading (greater than 100 mm/yr) back‐arc basin. The tectonic fabric of the Manus Basin was mapped and defined with the Sea MARC II sidescan sonar and bathymetric mapping system. Then dredge samples and cores were collected, and a towed bottom camera system was used to search for signs of hydrothermal activity.