The data set comprises of measurements of surface currents collected across the Indian Ocean in the region 50 E (the Gulf of Aden) to 100 E and 25 S to 10 N. The data were collected between 1854 and 1974. The surface currents, measured from ships' drift, have been compiled into 10 day periods and 1 degree latitude-longitude squares. For each of these the vector mean of all of the observations from all years has been calculated. With this amount of subdivision, coverage is often sparse and sometimes non-existent. The source material for this atlas was obtained from the UK Meteorological Office archive of historical surface currents and this data set was compiled by the Institute of Oceanographic Sciences Deacon Laboratory (IOSDL).