Bathymetry data was acquired during R/V METEOR cruise M86/1c in the Northeast Atlantic between 06.12.2011 and 23.12.2011. The main aim was the calibration of the EM122 at Gettysburg seamount. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval.Description of the data source:During the M86/1c cruise, the hull-mounted KONGSBERG EM122 multibeam echosounder (MBES) was utilized to perform bathymetric mapping in medium to deep waters. Two linear transducer arrays in a Mills Cross configuration transmit acoustic signals of a nominal sonar frequency of 12 kHz. With 432 soundings per swath, the emission cone has a dimension of 150° across track and 1° along track. With a reception obtained from 288 beams, the actual beam footprint is 1° by 2°. Depending on the roughness of the seafloor, the swath width on a flat bottom is generally maximum six times the water depth. For further information on the system, consult https://www.km.kongsberg.com/. The position and depth of the water column is estimated for each beam by using the detected two-way-travel time and the beam angle, ray-traced through the water column, utilizing a proper sound speed profile. During the M86/1c cruise the EM122 operated to map the Gettysburg seamount, while calibrating the EM122. Responsible person during this cruise / PI: Christian dos Santos Ferreira (cferreira@marum.de)Description of data processing:Postprocessing and products were conducted by the Seafloor-Imaging & Mapping group of MARUM/FB5, responsible person Paul Wintersteller (seafloor-imaging@marum.de). The open source software MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, https://www.mbari.org/products/research-software/mb-system, 2017) was utilized for this purpose. Tide corrections were applied to the M86/1c data; but corrections for roll, pitch, and heave were not necessary. The sound velocity profiles taken during the cruise were sufficient for the MBES data. Using Mbeditviz, artefacts were cleaned manually. NetCDF (GMT) grids of the edited data as well as statistics were created with mbgrid. The published bathymetric EM122 grid of the cruise M86/1c has a resolution of 35 m. No total propagated uncertainty (TPU) has been calculated to gather vertical or horizontal accuracy. A higher resolution is, at least partly, achievable. The grid extended with _num represents a raster dataset with the statistical number of beams/depths taken into account to create the depth of the cell. The extended _sd -grid contains the standard deviation for each cell. The DTMs projections are given in Geographic coordinate system Lat/Lon; Geodetic Datum: WGS84. All grids produced are retrievable through the PANGAEA database (www.pangaea.de).Chief Scientist: D. QuadfaselCSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2011/20120064.htm