Multibeam data were collected during R/V Sonne cruise SO231 leading to the continental margin off Mozambique. Multibeam sonar system was Kongsberg Simrad EM-120. Data are unprocessed and may contain outliers and blunders and should not be used for grid calculations and charting projects without further editing. The raw multibeam sonar data in Simrad multibeam processing format (*.all) were recorded with Simrad SIS software running on Windows operating system. The dataset consists of 1365 files in which are compressed with ZIP (3 hours in one archive file). One dataset contains a measurement period of half an hour. Simrad data files can be processed using the software packages CARIS HIPS/SIPS or with the open source software package MB-System (http://www.ldeo.columbia.edu/res/pi/MB-System/). Contact mailto:infobathy@awi.de for data access.