Multibeam echosounder (MBES) data recorded during RV POSEIDON cruise POS499 between 04.05.2016 and 22.05.2016 in the Mediterranean Sea. The aim of POS499 was to investigate several mud volcanoes from four regional areas of the Calabrian Arc with the MARUM AUV SEAL. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Detailed description of the data source: During the RV POSEIDON cruise POS499 the ELAC SB3050 multibeam echo sounder with a nominal sounding frequency of 50 kHz was utilized. 384 beams with an acoustical footprint of 1.5°(TX)/2°(RX) are formed for each ping. For further information consult http://www.mdsys.co.kr/down/ELAC/SB_3050.pdf. During the POS499 cruise the swath width has been set to AUTO mode and was commonly observed at around 80°. This given swath width refers to a coverage of about 1.6 times the water ‐depth and reduces the max. number of beams collected per ping to less than 240. Most of the time the multi‐ping mode has been used with a receiver reception gain value of 45dB. The recorded bathymetry covers in total 880 km and the mapped area is based on the bathymetry results from the M111 & M112 cruises. Responsible person for hydroacoustic during this cruise / PI: Paul Wintersteller (pwintersteller@marum.de)Chief Scientist: Gerhard Bohrmann (gbohrmann@marum.de) CR: https://elib.suub.uni-bremen.de/edocs/00105556-1.pdf CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2016/20160083.htm A special thanks goes to the watch keeper during POS499: A. K. Bachmann, S. Ceramicola, O. Candoni