This dataset contains sea surface temperature and salinity data collected from 2003 to 2021 in the South Pacific Ocean and Southern Ocean from Italian research vessels, in the framework of the Italian National Antarctic Research Programme (PNRA) scientific activities. Measurements have been obtained through thermosalinograph (TSG) during several cruises to Antarctica across the chokepoint between New Zealand and Ross Sea. On-board TSG devices have been regularly calibrated and continuously monitored in-between cruises; no appreciable sensor drift emerged. Independent water samples taken along the cruises have been used to validate the data; salinity measurement error was a few hundredths of a unit on the practical salinity scale. A careful quality control allowed to discard bad data for each single campaign. Furthermore, a sea ice flag has been included in the dataset for identifying valid data which could have been slightly affected by scattered sea ice contamination.