De Beers Marine undertake offshore marine diamond mining to depths of 130 m on the South African west coast using remote mining tools. A baseline and impact monitoring programme was developed for operations in their ML3 licence area, with the view to quantitatively assessing the direct and indirect effects of deep-water marine mining on benthic macrofaunal communities, and to monitor post-mining recovery. Benthic grab samples were collected from two mined and three unmined sites in 2003, 2008, 2009, 2011, using a Van Veen grab. Macrofauna was identified, and abundance and biomass determined. The data were made available to SADCO as a series of Excel sheets. At SADCO, the data were quality-controlled and transformed to comply with the Darwin Core/OBIS Schema. Funds for data operations were kindly provided by the Census of Marine Life International Cosmos Prize Fund, through a grant to Rutgers University.