The SPURS field campaigns utilized an extensive collection of in-water instruments and equipment to measure salinity, including the following:
- Ship-based measurements are collected from a ship, or with equipment that is mounted or towed while underway.
- Stationary instruments collect measurements from a pre-defined location that does not change, such as a mooring or tethered buoy.
- Free-drifting instruments collect measurements from an oceanic device that floats on the surface. Modern drifters are typically tracked by satellite or GPS.
- Mobile instruments collect measurements as they move through the water. These differ from drifters in that they do not move at the whim of a current, but can be directed to desired locations.