This dataset collection comprises two simulations; WINDS-M (Western Indian Ocean Simulation, Multidecadal) and WINDS-C (Western Indian Ocean Simulation, Climatological). Both simulations are high-resolution (1/50 degrees in the horizontal) from 1993-2020 (for WINDS-M) and 1993-2018 (for WINDS-C), using the Coastal and Regional Ocean Community model (CROCO). WINDS-M is forced at the lateral boundaries by daily output from the 1/12degrees CMEMS (Copernicus Marine Environment Monitoring Service) GLORYS12V1 global ocean reanalysis and barotropic tides from TPXO9, at the surface by hourly output from ERA5, and also includes climatological riverine fluxes. WINDS-C is forced at the lateral boundaries by a monthly climatology from the 1/12 degrees CMEMS GLORYS12V1 global ocean reanalysis and barotropic tides from TPXO9, at the surface by a monthly climatology from ERA5, and also includes climatological riverine fluxes. High frequency (0.5h) surface currents are provided for Lagrangian analyses, and other surface fields are provided at a daily frequency for both simulations. The simulations were run using funding through the Doctoral Training Partnership in Environmental Research grant NE/S007474/1 titled Marine dispersal and retention in the western Indian Ocean