This proposal requests funding to design, construct and document instrumentation to measure in situ geothermal/hydrogeological parameters in the upper 10 meters of deep seafloor sediments. The measurements will include the vertical geothermal gradient, vertical pore pressure gradient, and temperature/thermal conductivity and will be taken by repeated (pogo) penetration of a probe tethered with a standard oceanographic cable. A two-way acoustic data link between the ship and the instrument will also be developed. This instrumentation will support ongoing scientific research programs investigating the hydrogeological nature of the ocean floor such as the Ocean Drilling Program and RIDGE.