The islands of Crozet and Kerguelen are located at the junction of the Southern Indian Ocean and the Southern Ocean, an area of major environmental contrasts due to the juxtaposition of subtropical warm and salty waters and polar cold waters. Frontal structures generated by the Antarctic Circumpolar Current divide these oceans into several oceanographic zones. Several regionalisations have been carried out in recent decades, but only on the epipelagic or mesopelagic zones, without considering both together. As these frontal zones have a strong influence on environmental conditions and the distribution of biodiversity, it is important to be able to identify their spatial distribution and boundaries. The aim of this study was to identify the different hydrologic zones in the Indian sector of the Southern Ocean and the Southern Indian Ocean from oceanographic open access data. Temperature and salinity profiles from the surface to 1000 m depth between 2010 and 2020 were retrieved from Copernicus reanalyses. A functional PCA was applied to these data to account for the defined depth of the water column, followed by k-means clustering to identify regions with common hydrologic profile. We also calculated the mean and standard deviation of the cluster value for each geographical cell to identify stable areas and areas of high hydrologic variability. Each region was then linked to environmental data from the whole study area to characterise it. We were able to identify 7 regions, 4 in the Southern Indian Ocean and 3 in the Southern Ocean. The regions in the Southern Ocean are strongly explained by the frontal zones such as the Subantarctic and Polar fronts. Conversely, the regions in the Southern Indian Ocean are explained by differences in salinity, particularly in subsurface waters, associated with the action of the South Equatorial Current.