Precise seabeam2000 swath bathymetric data around Japan obtained by Hydrographic Department were compiled and displayed in common format, shaded relief maps and three dimensional whale-eyeﾕs views are produced from these data, which help us to understand the sea bottom topography intuitively. Statistical estimation was attempted for objective evaluation of the topography by means of the power spectrum slopes of the water depth profiles, The result suggests that the horst and graben structure characterizing the trench seaward slope is the origin of the values of the power spectrum slopes greater than 3.