CTD’s and Multi-Parameter Probes provide precise and simultaneous in-situ measurements, with a choice of parameters that can include Conductivity, Salinity, Temperature, Depth, Sound Velocity, Dissolved Oxygen, pH, Turbidity, Specific Ions, and Redox. Deployment of a single system, therefore, efficiently provides comprehensive data for a number of scientific disciplines at once. The probes, with an appropriate selection of measurement parameters, data display, and recording options are ideal for use by environmental scientists, engineers, and oceanographers. The small size, rugged construction, and DC operation of the equipment make it easily portable for work on land or for small boat operations. The systems operate effectively in lakes, rivers, coastal and estuarine waters, and open ocean areas of the world. Outputs from the sensors are transmitted via multi-conductor cable to a surface data display module or computer.