Sierra Leone was well mapped under British aid projects carried out in the 1960s and 1970s, but almost no mapping progress has been achieved in the last 25 years. Topographic mapping of the country was carried out by the British Directorate of Overseas Surveys (DOS) (now Ordnance Survey International (OSI)). A 1:50,000 scale map was compiled using photogrammetric techniques and sheets were published to cover quarter-degree quadrangles, with 13 nonstandard sheets for some border or coastal areas. This map was on a Transverse Mercator projection, modified Clarke 1880 ellipsoid, and second edition sheets were published by 1973 as five-color maps showing relief with 50 ft contours, to give complete coverage of Sierra Leone in 111 sheets. A derived map at 1:250,000 scale covered the country in four sheets and DOS also issued a single sheet 1:500,000 scale map, last published in its eighth edition in 1976. Larger scale DOS mapping included 1:2,500 scale township plans, most published as two-color photogrammetric plots, and a 1:10,000 scale series (DOS 219) covering the Freetown peninsula.
Current responsibility for mapping falls to the Directorate of Surveys and Lands (DSL) in the Department of Lands, Housing and the Environment. It participated in the DOS mapping programs and was originally established in 1925. DSL continues to use the DOS base mapping, though almost no revision has taken place.
Soviet military topographic mapping of Sierra Leone exists at the following scales: 1:1,000,000 (4 sheets, complete coverage, published in 1986); 1:500,000 (4 sheets, complete coverage, published in 1985); 1:200,000 (17 sheets, complete coverage, published in 1985) and a city (scales differ) map of Freetown published in 1984. These products are available in print, digital raster and digital vector GIS formats from East View Geospatial.
Coastal waters are mapped on Admiralty charts compiled by the British Hydrographic Office (HO).
Geological mapping of Sierra Leone has been carried out by the Geological Survey Division, also under British aid projects in the 1960s. Maps included 1:1,000,000 and 1:250,000 coverage, and some local 1:50,000 sheets.
Full-color soil and resources mapping was carried out at large scales for some of the country during the years of British involvement by the British Land Resources Development Centre (LRDC), (now Natural Resources Institute (NRI)).
The Land and Water Development Division of the Department of Agriculture produced monochrome vegetation, land use, land systems and land suitability mapping in the 1980s, using 1:500,000 and 1:1,000,000 topographic bases.
1:1,250 scale cadastral mapping was carried out by DSL in the 1970s for major district headquarters.
The only available recent mapping is a road map of the country published by Shell Sierra Leone Ltd in 1988 and a tourist map from International Travel Maps (ITM) , Vancouver.