This is a project to support a six week time-series measurement program of sea floor seismicity, and monitoring of a number of high and low temperature vents. The instruments will be deployed on the Endeavor Segment of the Juan de Fuca Ridge; ALVIN will be used for emplacement and recovery. The deployment will consist of an array of ocean bottom seismometers, operated by J. McClain of UC, Davis under a subcontract to the University of Washington, conventional thermocouple arrays, and instrumented water column moorings involving standard rotary current meters. In addition "innovative" instruments such as a time-lapse video camera, and an electromagnetic flow meter will be emplaced. The hope is to obtain a record of temporal variations in thermal and fluid output from the vents and that can be correlated with observed seismicity. This work is seen as an excellent opportunity to deploy and test some new types of instruments for monitoring hydrothermal vents. The project is part of the RIDGE Initiative, a component of Global Geosciences. If successful, this work would be an important step toward characterizing temporal variability in hydrothermal output from an ocean ridge vent field and could lead to significant advances in long term monitoring of ridge crest hydrothermal activity.