The BAHIAS cruise was one of the pioneering prospective cruises conducted on the Bay of Cienfuegos in Cuba (Leg 1 from 28 May to 7 June 2008) and on the Sonda de Campeche site in Mexico (Leg 2, from 15 to 22 June 2008). The main aim of these two legs was to complement existing data so that an initial assessment of carbon cycles and those of related nutrients (N, P, Si) and determine the dispersal of terrigenous, anthropogenic inputs. The main objectives were therefore to: - determine the spatial distribution and short term variability of the physical, chemical and trophic characteristics of waters to establish an environmental typology and later be able to supplement data or validate operations to model hydrodynamics or particulate transport; - determine the quantitative significance of biogeochemical fluxes between the benthic compartment and the pelagic compartment and use the environmental typology data to analyze the factors which could explain their distribution. In practical terms, the following operations were scheduled on the two sites: -Spatial coverage of water characteristics, -Spatial coverage of fluxes at the water-sediment interface, -Two cycles of high-frequency time monitoring over 25 hours. Leg 1 (Bay of Cienfuegos, Cuba) took place in the Caribbean SEa from 28 May 2008 to 7 June 2008. Leg 2 (Sonda de Campeche, Mexico) took place in the Gulf of Mexico from 15 to 22 June 2008.