In May, 1977, the first non‐military version of a multi‐beam, wide swath, deep ocean, bathymetric sonar was placed in service. Called SEA BEAM, this equipment provides high resolution bathymetric data across a swath width approximately equal to 78% of the depth. Angu ar resolution is 2.7° with a maximum operating depth of 11,000 m. Real time displays include a CRT presentation of the thwartship profile and a continuous strip chart of bottom contours. All sounding data are recorded on digital magnetic tape for final processing and merging with corrected navigation data. More recently, a companion system called HYDRO CHART has gone into operation for continental shelf surveys.