Abstract: Seabed survey using wideband synthetic aperture sonar can provide high resolution images and maps (a cubic meter voxel at a few kilometres range) using a reasonable array size (2 metres) and a rather low frequency range (6-12 kHz). A low frequency prototype has been constructed in the frame of the MAST project SAMI "Synthetic Aperture Mapping and Imaging". A large amount of experimental data was obtained at sea and stored for further processing. The paper will show some of these results. It will display both synthetic images and 3D maps.