The oceanographic cruise MEDCOR in the Strait of Sicily was designed primarily to (i) complete the multiswath map ofthe deep water coral (dwc) site in the South of Malta, acquiring new biogeological and hydrological data from this area, (ii) collect and maintain live corals in tanks to conduct onboard and laboratory experiments on the effects of ocean acidification on dwc and assess dwc microbiological ecology, (iii) collect living corals for genetic studies; (iv) collect paired water samples and living dwc for geochemical studies related to water mass circulation, (v) evaluate anthropogenic impact on selected deep sea areas, (vi) explore a pockmarks/mud volcanoes area in the Gela basin considered to host chemosynthetic biota. The ocean acidification and microbial ecology experiments have been conducted in the frame of the COMP project (Réponse des coraux méditerranéens profonds aux changements climatiques globaux).