Grids that integrate land and seafloor elevations are needed by planners using LIS/GIS software to manage the US coastal zone, which encompasses the coastal states out to the country's 200-mile offshore limit. The National Geophysical Data Center is addressing this need by assembling a gridded database that merges the US Geological Survey 3-arc-second DEMs with a vast compilation of hydrographic soundings collected by the National Ocean Service and various academic institutions. The principal component of the database is 3-arc-second elevation grids, of areas 1° in longitude by 1° in latitude, in which elevations are resolved to 1/10 of a meter. The database also includes grids containing the number of soundings enclosed by each cell in the offshore areas of the elevation grids, and images of both the elevation and sounding density grids. The latter are in common graphic formats that can be displayed by a range of UNIX-based and personal computer software. This paper describes how the database is being constructed and the novel software that accompanies the grids on CD/DVD. The software allows the user to navigate the CD/DVD, view grid images, and modify the grids for importation into GIS/LIS applications.