This dataset contains raw CTD (conductivity, temperature, depth probe) data for stations conducted during the cruise SO301 in winter 2023/24 in the Indian Ocean. The goal was to observe the extent of water masses emitted from the Kairei hydrothermal vent site. For this purpose additional sensors were mounted to the CTD system: a Seapoint turbidity sensor and an Eh sensor manufactured by the PMEL and for some stations an Eh sensor manufactured by AMT. CTD stations were executed as normal vertical casts, repeated vertical up- and downcasts or as repeated up- and downcasts during slow ship travel creating a zig-zag-like pattern. Additionally data with the raw, unprocessed position data from a Sonardyne acoustic underwater position tracker are supplied as well as scans of the handwritten deployment protocols. The acoustic tracker was mounted at the CTD rosette for most of the stations.