Water samples were taken during the expedition OASIS (Organic very short lived substances and their Air–Sea exchange from the Indian Ocean to the Stratosphere) cruise (S0235) in the Indian Ocean on board the R/V Sonne I in 2014. Water samples were collected from ship's moonpool during underway and from CTD Niskin bottles. CTD samples were analyzed for bacteria (flow cytometry) and phytoplankton counts (microscopy), and dissolved organic carbon and nitrogen (TOC analyzer), transparent exopolymer particles and coomassie stainable particles (microscopy). In-situ pump samples were also analyzed for bacteria (flow cytometry) and dissolved organic carbon and nitrogen (DOC, DON) (TOC analyzer).