Conductivity, Temperature and Depth (CTD) devices are widely used in marine scientific measurement for in-situ measurement. OSIL staff are highly experienced in this field and offer a comprehensive range of CTD products together with full service, repair and calibration facilities. Sound Velocity (SV) measurements play an important role in the calibration of sonar equipment. OSIL offers state-of-the-art sound velocimeters which provide the highest accuracy sound speed data.