Indian Ocean surface circulation is an important part of the global ocean conveyor belt, and is connected via two important gateways including the Indonesian Throughflow, and the Agulha Leakage. Changes in the surface hydrography of the Indian Ocean may therefore impact on the global overturning circulation. Here we present planktonic foraminifera-based stack of oxygen isotopes as proxy for surface salinity from the surface Indian Ocean. We find that Indian Ocean surface salinity (along with temperature) increases during glacial intensification. We link this phenomenon to dynamics in the Indonesian Archipelago.