New profiler and sonobuoy data are presented to supplement the existing geophysical data in the Tasman area. The tectonically disturbed western edge of the Campbell Plateau extends outward as a deep-sea fracture zone that separates 80 m.y. old sea floor to the east from the 30 m.y. old Emerald Basin (Site 278). A 600-m regional depth change occurs at the boundary. The effeciveness of bottom currents on sedimentation is shown on the profiler section from the Campbell Plateau and the western Tasman Sea. A possible marginal rift, now buried, can be inferred from profiler data taken from near sites 275 and 276. A widespread reflector on the plateau has been identified as being in the region of the Cenozoic/Mesozoic boundary. A normally faulted erosion surface on the South Tasman Rise corresponds with the Oligocene-Late Eocene unconformity. A large east-west graben between the South Tasman Rise and Tasmania may represent an earlier rift that predates the rifted east-west margin drilled south of the rise (Site 280). Sonobuoy refraction data reveal a somewhat atypical structure section in the Central Tasman, where a 7.1- to 7.4-km/sec layer at a depth of 7.5 km supplants the typical 6.8-km/sec oceanic layer.