Seabed photographs taken along OFOS profile PS81/268-1 during POLARSTERN cruise ANT-XXIX/4

The Ocean Floor Observation System (OFOS), a towed underwater system equipped with a high-resolution digital camera (ISITEC, CANON EOS 1Ds Mark III), was used to visually inspect the sea floor at an altitude of about 1.5-2 m relative to the seabed in areas where flares were detected. In addition to the provided live feed, the camera was programmed to take high-resolution (21 megapixels) photographs of the sea floor every 30 s. Underwater-navigation was achieved using the shipboard IXSEA Posidonia ultra short baseline system, with an accuracy of 5-10 m, and these data were used to establish the OFOS tracks and the positions of each photograph taken.