Description: Plate tectonics and ocean bathymetry are discussed. Bathymetry is the study of ocean depth, which is affected in some regions by plate tectonics and mantle dynamics. Mid-ocean ridges are formed at plate boundaries where mantle material is rising to the ocean crust and solidifying as it cools to form new ocean crust material. Seamounts are volcanoes that have formed from molten mantle material pushing up through the ocean crust, but these volcanoes lie below sea level. These features are measured using acoustic depth profiling. Ocean water properties, such as temperature and salinity, as well as the methods used to measure them are also discussed.