This is a two.leg six ALVIN dive cruise to conduct a program of instrument deployment, mapping of flow related patterns near the seafloor, and in situ and laboratory califbration of a new suite of sensitive seafloor hydrothermal instrumentation. The program will collect continuous time series diffuse hydrothermal flow rates and temperatures over a period of about 40 days. A mappling program using similar instrumentation will examine flow both out of and into cracks and fissures in the bassltic basement rock in the vicinity of the vent field.