This British Geological Survey (BGS) marine geophysical survey took place during August 2004 in the Outer Bristol Channel aboard the RV Prince Madog. Netsurvey Ltd were commissioned to provide multibeam services. This survey was undertaken for the Outer Bristol Channel Marine Habitat Study (OBCMHS) as part of a series of five surveys. The OBCMHS was principally funded by the Aggregate Levy Sustainability Fund, MALSF, (administered in Wales by the Welsh Assembly Government), the Sustainable Land Won and Marine Dredged Aggregate Minerals Programme of the Office of the Deputy Prime Minister (ODPM), administered by Mineral Industry Research Organisation (MIRO), with contributions from others. Sea floor data collected were high-resolution multibeam bathymetry and side-scan sonar (on selected lines). Subsurface data were gathered using a surface tow boomer (on selected lines). The multibeam data adds to the data collected on a previous survey in 2003 and multibeam products include data from the 2003 survey. Most of the data were recorded digitally. Some paper records were also generated also. These data are archived with the MEDIN Data Archive Centres (DAC), including the BGS DAC for geology and geophysics and the UKHO DAC for bathymetry data. Technical details of the survey are contained in BGS Cruise report IR/05/082 (http://nora.nerc.ac.uk/id/eprint/11121/). For further information on the surveys and general information on the OBCMHS see the final report (Mackie et al, 2006. BIOMOR Reports 4:ISBN 0-7200-0569-8).