Multibeam echosounder (MBES) data recorded during RV METEOR cruise M143 between 12.12.2017 and 22.12.2017 in the Black Sea. The expedition aimed to investigate possible areas of seafloor depressions and slope failure along the shallow part of the Black Sea margin in the Danube Delta by bathymetry mapping and water column observation. A second emphasis is on collecting 38 kHz echosounder data in combination with multibeam water column images for quantification of gas emissions. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Description of data source: During the RV METEOR cruise M143 the hull-mounted Kongsberg EM122 multibeam echosounder with a nominal sounding frequency of 12 kHz was utilized. 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 angle was set to 130° and the use the of the high-density equidistant and the dual-swath mode of the EM122 resulted in up to 864 soundings per ping. The survey speed was varying between 3 and 12 knots with around 8 knots during multibeam bathymetric mapping surveys. The EM122 was recording constantly within the Romanian border with the aim to map slumping and sliding zones. The data quality was generally good, though affected by unstable weather conditions. Soft underground and shallow water depth resulted also in a strong nadir artefact, the so called 'Eric's Horn' type artefacts, which were later removed manually during the post processing phase. Responsible person during this cruise / PI: Michael Riedel (mriedel@geomar.de) Chief Scientist: M. Riedel (mriedel@geomar.de) CR: http://oceanrep.geomar.de/42646/7/geomar_rep_ns_42_2018.pdf CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2017/20170255.htm A special thanks goes to the watch keeper during M143: Florian Gausepohl, Iason-Zois Gazis, Line Hähnel, Mareike Kampmeier