Developed and built in 1982 for simultaneous bathy- metric and reflectivity mapping of the deep ocean by the Hawaii Institute of Geophysics, SeaMARC II was a breakthrough in sea-floor mapping technology. The design was developed cooperatively by industry and academia, and the system has served as a prototype for a new generation of mapping tools for operation in both shallow and deep water._x000D_
Research programs using the SeaMARC II system have focussed on basic research into the geophysical evo- lution of the Pacific, ranging from intra-atoll mapping to surveys of the deep-sea trenches. During the past few years most work has been concentrated on detailed investigations of the morphology of mid-ocean spread- ing centers, seamounts, and the subduction zones which surround the Pacific. The detail provided by the high resolution, 10-km wide side-scan sonar images of fault and fold structures, combined with the swath of bathy- metric information obtained simultaneously, allow previ- ously unattainable analysis of seafloor morphology and are leading to development of detailed models for ocean crust genesis and deformation.