An electronic instrument designed to measure very accurate, nearly continuous profiles of conductivity, temperature, and pressure (depth) in the water column. It is usually lowered on the end of a conducting cable through which the real-time measurements are transmitted to a recorder on the ship. Today there are also self-contained instruments (i.e., with an internal memory). Salinity is computed subsequently from the conductivity and temperature measurements. Accuracies are typically ±0. 005 psu, 0. 005 K, and 0. 15% full scale for conductivity, temperature, and depth, respectively.