Vertical distributions of salinity, temperature and currents were measured in the upper 1000 m of the tropical South Pacific Ocean along 165¿E and 180¿ and along the equator in between, during the WESPALIS-1 cruise (Oct./Nov. 1999). The high salinity tongue of the South Pacific subtropical overturning cell (STC) is eroded along its westward and equatorward isopycnal flow. Part of the STC is contained in the eastward flow of the EUC which is then upwelled further east. During La Ni¿a, another, shallower, portion of the STC layer flows directly towards the equator and is upwelled but confined south of the equator. During El Ni¿o, there is also possibly intense exchange of heat between the STC and the equatorial mixed layer.