Full-depth conductivity–temperature–depth/hydrographic measurements were taken in May–June 1995 along 28115 0 , 35115 0 , and 43115 0 S from the Chilean coast to 86–881W from the R.V. Sonne. Sections of potential temperature, salinity, neutral density, and oxygen are presented to illustrate the water-column structure in this sparsely sampled region. A more comprehensive database on all available hydrographic data from the region was compiled. These data and available meteorological data are used to help in the interpretation of the Sonne results. A number of important features found in the sections are discussed, including a shallow salinity minimum (apparently ventilated from south of $371S), salt fingering as a possible mechanism to transport high-salinity subtropical water into the shallow salinity minimum, Equatorial Subsurface Water, Subantarctic Mode Water, and Antarctic Intermediate Water. Geostrophic calculations of alongshore flow show the poleward Peru–Chile Undercurrent at each of the three sections with a poleward descending core and peak velocities of $10 cm s À1 . As in earlier works, a deep Pacific outflow is found near the Chilean coast, part of a clockwise deep circulation in the Chile Basin.