Physical and biological data were gathered over the Campeche Canyon area, Gulf of Mexico, in summer 1999. These include hydrographical and meteorological parameters, and oxygen content, as well as, at some oceanographic stations, suspended particulate matter (SPM), chlorophyll-a, and in vivo natural fluorescence profiles. Dry air from the east set up a latent heat flux that ranged from 50 to 300 Wm-2. The wind mixed layer (ML) was isothermal and averaged 40 m thick, but with a noticeable increase of oxygen supersaturation toward the northwest. Temperature and dynamic height structure reveal an anticyclone-cyclone eddy pair. At the southeastern part of the study area a noticeable thermal gradient was observed toward the shelf break of the Campeche Bank, which corresponded to a tilting up (doming) of low oxygen saturation midwater to near the base of the ML. This doming of isotherms along the margin of the Campeche escarpment is likely an upper-ocean response to the sharp gradient in water depth between the canyon and outer continental shelf. It is suggested that the doming of midwater on to the Campeche escarpment and at the head of the Canyon, as denoted by locally low values of oxygen saturation, plays an important role in the biological patterns. Throughout the field area, the values of total SPM were higher than reported previously for subtropical open ocean environments. The impact of autotrophic-heterotrophic biogeochemical processes on chlorophyll was reflected in the local deepening of the deep of chlorophyll maximum (DCM) and the depth of the euphotic zone within the anticyclonic eddy.