Seafloor geodesy is a branch of geophysics dedicated to measuring the movement of tectonic plates and the deformation of the Earth's crust beneath the ocean's surface. Using advanced instruments like seafloor geodetic sensors, GPS-equipped buoys, and satellites, scientists monitor subtle changes in the seafloor's position, which can provide valuable insights into seismic activity, volcanic eruptions, and tsunamis. This field offers a unique perspective on plate tectonics, as it allows researchers to study regions previously inaccessible due to their underwater location. By analyzing data collected from seafloor geodesy, scientists can better understand the dynamics of Earth's crust, improve earthquake and tsunami forecasting, and mitigate the risks associated with natural hazards in coastal regions. This book aims to shed light on some of the unexplored aspects of seafloor geodesy and the recent research in this field. It strives to provide a fair idea about this discipline and to help develop a better understanding of the latest advances within this field. This book on seafloor geodesy is a collective contribution of a renowned group of international experts.