Aerial photography has revolutionized the art of map making over land and if the depth of water could be measured from an aircraft a similar revolution might be expected in hydrography. In 1971 an airborne laser land profiler, designed and constructed at the Weapons Research Establishment, Adelaide, was put into service. At the suggestion of Captain J. H. S. Osborn, then the Hydrographer, R.A.N., this was modified to profile the sea bed and flight tested in June 1975. It was found that, in the vicinity of Adelaide, reflections from the sea bed could be obtained down to 30 m and in places down to 40 m. With an airborne device it becomes possible to survey an area instead of a line and work since has been concentrated on developing a system which will scan at right angles to the aircraft's track.