The characterization of physical and chemical regimes of one of the largest and deepest seafloor hydrothermal fields known, the Trans-Atlantic Geotraverse (TAG) field situated on the Mid-Atlantic Ridge near 26°N, 45°W, was the subject of a diving cruise by IW Atlantis II/Alvin during April and May. An international research team carried out multidisciplinary investigations of both active and inactive hydrothermal zones of the field. The investigation was designed to achieve several objectives supporting drilling of an active sulfide mound in the TAG field scheduled in late 1994 by the Ocean Drilling Program: to advance understanding of the role of seafloor hydrothermal activity in transferring heat and chemicals between the oceanic lithosphere and the ocean
to establish a quantitative baseline for these exchange processes prior to drilling the mound
to determine the structure of the mound.