Multibeam bathymetry raw and processed data (RESON Seabat T50Extended Range) of Research Vessel Littorina at Fehmarn Belt in the western part of the Baltic Sea. The raw data (.db format) were processed using QPS Qimera software (v 1.7), based on the following workflow: 0.Raw data -> 1.Apply correct Sound Velocity Profiles -> 2. correct lever arm offsets -> 3. Finalize with manual 2D and 3D point editing. The corrected soundings were used to create a GeoTIFF (EPSG Code:4326) .gsf data and GeoTIFF are provided. In addition software is provided with the aim of establishing a benchmark for terrain based navigation correction software using mutlibeam data. A) A script that allows to alter navigation solutions B) A script that allows to compare navigation solutions By altering the original and correct navigation and using the product as a basis for a terrain based navigation correction algorithm, the quality of such an algorithm can be measured by comparing its output to the original navigation. This in turn allows quantitative comparisons between different algorithms or settings. In addition to the original navigation some altered navigation files are provided (in .csv file format).