A Simrad multibeam model EM12/120S was used. This system provides a swath coverage of approximately 3.5 times the water depth. The system was set with constant spacing on the sea-bottom of the available 81 beams, so that the pixel size varied according to the water depth. The multibeam system furnished both detailed bathymetric soundings and 13 kHz sea-floor reflectivity (sonar) data. In general, the quality of the data we obtained can be considered good. The survey was planned and executed to obtain the full coverage of the seabottom with overlapping areas ranging around 20 % of the swaths. Data were stored in real time by the the Simrad MERMAID software on the ship's logging workstation.