During the RV Sonne cruise SO266, which took place between 15.10.2018 to 18.11.2018, bathymetry data based on multibeam echosounder (MBES) was recorded. The research area is located in the SW off Taiwan. The main focus of the cruise was the investigation of gas hydrate distributions influenced by different tectonic settings (at active and passive margins) and lithologies using the MEBO200 to collect sediment samples. The ship-mounded multibeam echosounder was used to collect detailed information about the drill sites containing bathymetry and backscatter data as well as water column information. Additionally it was accomplished to create a detailed map (5-15 m grid cell size) of the region SW off Taiwan, which shows structural features of the passive and active continental margins as well as gas hydrate linked morphologies such as mud volcanoes. The KONSBERG EM710 was used in addition to the KONGSBERG EM122 to map the continental slope.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 RV SONNE cruise SO266 the hull-mounted KONGSBERG EM122 multibeam echosounder systems was used in the areas of interest. This echosounder system uses nominal sounding frequencies of 10.5 to 13 kHz and was therefore used in water depth of more than 700 m. 288 beams with an acoustical footprint of 0.5°(TX)/1°(RX) are formed for each ping. Due to the use of the high-density equidistant and dual swath mode 864 soundings were received with every ping. During the cruise the swath width was set to 120° and partly to 130°. For further information consult https://www.km.kongsberg.com/. The EM122 was recording continuously during the cruise. To avoid signal interferences all used hydroacoustic systems were synchronized using the on-board K-Sync-Unit. During the hydroacoustic surveys the vessel speed was conducted to 11 kn. The vessel velocity was lowered to 3 kn for flare imaging surveys. The data quality was generally good, due to the good signal to noise ratio of the research vessel. Responsible person during this cruise / PI: Paul Wintersteller (pwintersteller@marum.de)Chief Scientist: G. Bohrmann (gbohrmann@marum.de) CR: not yetCSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2018/20180051.htmA special thanks goes to the following watch keeper during SO266: W. Cheng, J. Elger, H. Hsu, L. Kramer