A seabed survey for the purpose of habitat identification and mapping at the Greater Haig Fras recommended Marine Conservation Zone (rMCZ) site, west of Cornwall, UK. Comprising acoustic corridors overlying a 5 km triangular grid of ground-truth sampling stations. Three nested full coverage areas in the west, centre and east of the site. Acoustic survey by multibeam (bathymetry and backscatter) and sidescan sonar (part coverage only). Ground-truth sampling by grabs and underwater cameras (video & stills images). Broadscale habitat (BSH) and habitat FOCI (Features of Conservation Interest) recorded at time of sampling and included in cruise/survey report. More in-depth interpretation to be made in a Post-Survey Site Report, following integrated assessment of acoustics and outputs from laboratory analysis of benthic samples. Central, full coverage area targeted to provide data sets against which the capabilities of AutoSub (an AUV owned by National Oceanogrephic Centre (NOC), Southampton, UK) could be tested. These data are archived with the Marine Environmental Data and Information Network (MEDIN) Data Archive Centres (DACs) including the British Geological Survey (BGS) DAC for geology and geophysics, The Archive for Marine Species and Habitats Data (DASSH) and the United Kingdom Hydrographic Office (UKHO) bathymetry DAC. The full site data package including raw is also available on request from BGS.