Anyone doing CTD profiling, especially interested in detailed transects may be interested in the UnderwayCTD system. Like an XBT, the UnderwayCTD probe drops in freefall and gathers the CTD profile on the downcast. Unlike an XBT (or xCTD), the probe is tethered to the ship and is pulled back after every cast to be re-used hundreds or thousands of times. Data quality comes quite close to a fixed CTD station but the research vessel never has to stop on station, allowing great new possibilities for CTD datasets. Have a look at for more details.