Description: Multibeam echosounder (MBES) data recorded during RV METEOR cruise M134 between 16.01.2017 and 18.02.2017 around South Georgia. The main objective of was to investigate emissions of free gas from cross‐shelf troughs of South Georgia, their distribution, quantification, and sources for methane ebullition sites in sub‐Antarctic waters. Another objective was the mapping of the glacial bathymetry on the shelf. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Description of the data sources: During the cruise RV METEOR M134/1 the hull-mounted Kongsberg EM710 with a nominal sounding frequency of 70-100 kHz was utilized. 256 beams with an acoustical footprint of 1°(Tx)/1°(Rx) are formed for each ping. For further information consult: http://epic.awi.de/26726/1/Kon2007b.pdf. The main purposes of most of the surveys were mapping for bathymetry and searching for gas flares in the water column. The EM710 was recording almost continuously. During this cruise the swath width was set to 130° and the use of the high-density equidistant and the dual-swath mode of the EM710 resulted in up to 800 soundings per ping. The survey speed was kept between 6-10 knots depending on weather conditions and flare surveying. Responsible person during this cruise / PI: Wilhelm Weinrebe (wweinrebe@geomar.de) & Paul Wintersteller (pwintersteller@marum.de). Chief Scientist: G. Bohrmann (gbohrmann@marum.de) CR: https://elib.suub.uni-bremen.de/edocs/00106081-1.pdf CSR: http://www.bsh.de/aktdat/dod/fahrtergebnis/2017/20170002.htm A special thanks goes to the watch keeper during M134/1: Viola Bihler, Maximilian Grahs, Miriam Römer and Nikolas Stange

Description: Multibeam echosounder (MBES) data recorded during RV METEOR cruise M134/1 between 16.01.2017 and 18.02.2017 around South Georgia. The main objective of was to investigate emissions of free gas from cross‐shelf troughs of South Georgia, their distribution, quantification, and sources for methane ebullition sites in sub‐Antarctic waters. Another objective was the mapping of the glacial bathymetry on the shelf. 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 cruise RV METEOR M134/1 the hull-mounted Kongsberg EM122 with a nominal sonar frequency of 12 kHz was utilized. The EM122 system is a deep‐water multibeam echosounder providing accurate bathymetric mapping down to full ocean depth. 288 beams with an acoustical footprint of 1°(TX)/2°(RX) are formed for each ping. For further information consult https://www.km.kongsberg.com/. During this cruise the swath width was set to 130° and the high-density equidistant and the dual-swath mode of the EM122 was used, resulting in up to 864 soundings per ping. The survey speed was kept between 6-10 knots depending on weather conditions and flare surveying. The main purposes of most of the surveys were mapping for bathymetry and searching for gas flares in the water column. Since the EM710 was recording almost continuously, the EM122 was mainly used for transits, in water depth deeper than 500 m or for short dedicated surveys in order to achieve better backscatter information. Responsible person during this cruise / PI: Wilhelm Weinrebe (wweinrebe@geomar.de) & Paul Wintersteller (pwintersteller@marum.de). Chief Scientist: G. Bohrmann (gbohrmann@marum.de) CR: https://elib.suub.uni-bremen.de/edocs/00106081-1.pdf CSR: http://www.bsh.de/aktdat/dod/fahrtergebnis/2017/20170002.htm A special thanks goes to the watch keeper during M134/1: Viola Bihler, Maximilian Grahs, Miriam Römer and Nikolas Stange.