NGDC's GEOphysical DAta System (GEODAS) allows On-line Searches and data Retrieval of several of NGDC's geophysical databases, including Marine Trackline Geophysics Data, Aeromagnetic Survey Data, the NOS Hydrograpic Surveys database, US Coastal Relief Model Grids, Great Lakes Bathymetry Grids and ETOPO1 Global Relief Grids