This oceanographic instrumentation acquisition project will allow the construction of new transducer arrays and purchase of electronic spares for the University of Hawaii's SEAMARC II side-scan sonar system. The new instrumentation will augment that already in a pool of shared use equipment that is made available to users of the institution's research vessel. The SEAMARC II is an acoustic seafloor survey system that simultaneously produces both high quality sonar images of the sea bed and bathymetric contour charts along a swath of the seafloor. An acoustic array is towed behind a research vessel at speeds up to 10 knots while on board computers produce near-real time displays of seafloor morphology. Such data is on interest to geologists and geophysicists studying plate tectonics, mid-ocean ridges, continental margins and other research topics sponsored by the NSF. Cost-sharing is being provided by the University of Hawaii.