A coring and squeezing technique has been modified and simplified to permit the collection of closely spaced samples of pore water from both the saturated and unsaturated zones on land, and bottom sediments in lakes and rivers. Samples of the pore water are obtained by placing short sections of sediment from freshly collected cores in a mechanical squeezer and applying pressure to extrude the contained fluid into a syringe. If coarse incompressible sediments are encountered, the pore water is removed by an immiscible-fluid displacement technique. The pore water samples are analyzed by standard methods for major and minor components. Also, in situ measurements of some parameters are carried out by directly inserting electrodes into the fresh sediment. These methods are being applied at a number of locations in southern Ontario to study the quality of waters in the unsaturated zone, the chemistry of natural and contaminated groundwaters, and the significance of seepage and baseflow in lakes and rivers respectively.