A CTD rosette is lowered into the water from Research Vessel Kilo Moana. A CTD measures conductivity, temperature, and depth. Measurements are collected throughout the water column, from the ocean surface as the instrument is lowered to near the seafloor, and then on the way back to the surface. This image was taken during the Deepwater Surveys of World War II U.S. Cultural Assets in the Saipan Channel expedition.