The conventional approach in deep-sea studies is to collect samples at the seafloor, to recover them, and to make observations and analyses on board the research vessel. However, because of artefacts induced when samples are subjected to changes in hydrostatic pressure and (often) temperature during transfer to the surface, accurate data from the deep sea are difficult, if not impossible to obtain. It is therefore preferable to carry out observations, experiments and measurements directly at the seafloor (in situ). Such studies can be conducted using free-falling lander systems ("benthic landers").
A benthic lander is an unmanned vehicle that falls to the seafloor unattached to any cable, and then operates autonomously on the bottom. At the end of the deployment, ballast weights are released pre-programmed or on acoustic demand. The lander floats back to the surface by virtue of its positive buoyancy.
The project group runs different systems of basically the same design (GEOMAR-type). These systems, however, were used for different purposes and thus were equipped with different scientific modules, like current meters, respiration chambers, optical oxygen sensors, microprofiler, sediment traps and camera systems.