This dataset contains outputs of four simulations from an ocean-biogeochemistry (NEMO v.4.0.4 - ERSEM) model over the South East Asia region. Atmospheric forcing is provided by ERA5, with lateral ocean boundaries from the CMEMS global forecast. Biogeochemical tracers are initialised and forced by a combination of world ocean atlas, GloDAP, and OC-CCI data. Output is provided as daily/monthly files on {t,u,v,w}-grid. Additional monthly output used in the construction of a nitrogen budget is also provided. For all simulations, riverine input and nitrogen deposition is input into the marine environment. The four simulations include basline scenario conditions using 2015 as a reference, and then three hindcasts including nitrogen budget under current legilation, under maximum technically feasible reduction in overall nitrogen production, and under maximum technically feasible reduction in overall nitrogen production plus a change in human diet conditions. The hindcasts are used to assess future behaviour under a given scenario. The model configuration is named SAsia. The outputs were generated under the South Asian Nitrogen Hub (SANH; NE/S009019/1) project.