The Slocum Glider is a state-of-the-art autonomous underwater vehicle (AUV) that moves up and down in the ocean by changing its buoyancy. Wings allow steerable gliding, thus horizontal propulsion. The vehicle traces a saw-tooth profile and can sample depth-resolved temperature, conductivity (salinity) plus bio-optical properties (such as radiance, irradiance, light scattering, chlorophyll fluorescence, dissolved organic matter fluorescence and beam attenuation.
At the surface, the gliders fix their position via GPS, communicate the data and commands via ARGOS/Iridium satellite links, then adjust their course using dead reckoning before their next dive. The gliders carry an altimeter, thus they can collect data to within a few meters of the bottom before beginning their ascent. Slocum gliders can be deployed for ~1 month, after which they are commanded to stop at a pre-determined location for recovery (e.g. a near-shore location which is safer to reach in a small vessel).