Multibeam data were collected during R/V Polarstern cruise ARK-XVIII/1. Data recording was executed in Iceland Sea and Greenland Sea. Data are unprocessed and may contain outliers and blunders. Therefore the data should not directly be used for grid calculations and charting projects but need to be edited furthermore. One file contains a measurement period not exceeding eight hours. The dataset consists of 181 files in ATLAS SURF format which are compressed with GZIP to size of 1.4 GB. SURF 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/). The source code for an application programming interface (API) to read and write SURF data is released by the Hydrosweep manufacturer Atlas Hydrographic, Bremen, and published under the GNU GPL. Contact mailto:infobathy@awi.de for data access.