Accurate and reliable, high-resolution seafloor bathymetry is essential to many aspects of oceanographic research. Global bathymetry is also used in many areas outside of the scientific community including: K-1 teaching of earth science and seafloor geography; undergraduate-level earth science and plate tectonics; law of the sea; US Naval operations; mineral exploration; planning of fiber-optic cable routing and general interest by the public. The global bathymetry map derived from satellite gravity by Sandwell?s group is now so widely used that it has become the public ?face of the deep? displayed by Google Earth. Over the next 3 to 5 years, a wealth of new marine gravity data will be provided by three currently operating satellite altimeters CryoSat, Jason-1, and Envisat. This project has the aim of using the new data to improve the accuracy of the global marine gravity field by at least a factor of two and in some areas a factor of four. Given the very wide use of satellite-derived bathymetry, the broader impacts of this work are both evident and profound.