Abstract The bivariate distribution of water characteristics in the Pacific Ocean is studied using 155 hydrographic stations. Separate diagrams of potential temperature against salinity give the distributions for the North, the South, and the entire Pacific Ocean. The dominant feature in all the diagrams, an enormous mode near 1·5 C, 34·7 per mille, results largely from water below 2000 m. The mode is at 1·75 C in the South Pacific distribution. It is stronger in the North Pacific distribution and lies at 1·25 C. This lower temperature is surprising, but apparently explicable. A mode at 4·5 C, 34·55 per mille, Tropical Water, is due mainly to water between the Tropics at depths from 700m. to 1100 m. It is associated with a layer of minimum salinity extending through much of its region of occurrence. Two other waters characterized by extensive salinity minimum layers are represented by ridges in the distributions. These are identified and their relationships with Tropical Water discussed. Also discernible in the distributions are features representing the water of the thermocline layers above the salinity minimum layers. Surface layers account for most of the spreading of the distributions from the modes and important ridges. Unlike the Atlantic and Indian Oceans, the Pacific shows no modes which are far removed from the principal ones. Univariate distributions of characteristics are presented. Means and certain percentiles are tabulated.