Abstract: The collector filters and encapsulates pore water, in-situ, from unconsolted sediments. A pressure casing mounts a collection cylinder having a valved inlet opening for receiving the sediment pore water through a 1 micron filter. The valve is spring pressed to a closed position and opens in response to hydrostatic pressure. A second valve closes the inlet to the spring-pressed poppet valve. Trigger means initiate the opening of the second valve to expose the poppet valve to the hydrostatic pressure. Preferably, the exposure is accomplished in a delayed manner to assure proper positioning of the sampler before admission of the pore water to the cylinder.