SonTek CastAway-CTD

The SonTek CastAway-CTD is a lightweight, easy-to-use instrument designed for quick and accurate conductivity, salinity/TDS, temperature, and depth profiles.


Each CastAway-CTD cast is referenced with time and location using its built-in GPS receiver. Latitude and longitude are acquired both before and after each profile. Plots of conductivity, temperature, salinity and sound speed versus depth can be viewed immediately on the CastAway’s integrated color LCD screen in the field. Raw data can be easily downloaded via Bluetooth to a Windows computer for detailed analysis and export at any time.

The CastAway can easily be carried by even a small drone and lowered through the water column to rapidly profile a pit lake for salinity/TDS and conductivity, including the presence of layers of different water quality. These layers can then be targeted for water quality sampling with MLC’s proprietary single- or twin-lock discrete samplers.


  • Designed for CTD profiling down to 100 m including thermocline profiling
  • Can also be used for sensor verification, speed of sound profiles, and more
  • Super-fast sampling rate and sensor response with 1 m/second free fall design
  • Integrated GPS positioning/date/time
  • Real-time display screen
  • No user calibration needed
  • No tools, computers or cables required
  • Wireless data transfer


  • Standard sensor: measures conductivity, temperature, pressure and includes GPS. Also, calculated salinity, sound speed, density, depth and specific conductivity
  • Connectivity: Bluetooth
  • Salinity accuracy 0.1 PSU
  • Weight: 0.45 kg
  • Diameter: 8.4 mm
  • Length: 20.3 mm
  • Sampling rate: 5 Hz
  • Max. depth: 100 m
  • Battery type: AA Alkaline
  • Temperature accuracy: 0.05°C
  • Battery duration: 40 hr

Contact us for CastAway rental hire prices