The data were collected as part of the South Atlantic Gateway in the global conveyor belt (SAGA) project. The general objective of the SAGA project is to quantify and monitor the returning limb of the Atlantic Meridional Overturning Circulation in the South Atlantic Ocean, with special attention to the interior-ocean zonal flows linking the eastern and western South Atlantic basins. As part of the project, the SAGA-34.5S cruise was carried out from February 1st to March 15th, 2022, on board the R/V Sarmiento de Gamboa. For the study of an Agulhas Ring, 10 hydrographic stations of this cruise have been selected and divided into two transects: a zonal transect from stations 75 to 80, sampling the South Atlantic waters; and a meridional transect from stations 80 to 84, sampling the AR. At each station, vertical profiles have been obtained by a conductivity-temperature-depth (CTD) SBE911plus (https://doi.pangaea.de/10.1594/PANGAEA.972150). Water samples were also taken by 24 Niskin bottles for dissolved oxygen (µmol/ kg), pH (this Dataset), and nitrates (µmol/ L) (https://doi.pangaea.de/10.1594/PANGAEA.972151). These data are complemented with near-surface salinity and temperature values obtained from a Thermosalinograph (TSG) (https://doi.pangaea.de/10.1594/PANGAEA.972164), as well as velocity profiles from the sea surface down to depths of ≈ 600-900 m collected from a shipboard acoustic Doppler current profiler (SADCP, of 75 and 150 kHz, respectively) (datasets IDs). The temporal coverage of the data is 3 days (March 4-6, 2022) and the spatial coverage includes 34-38ºS and 6ºW-6ºE (southeast Atlantic Ocean).