Fugro Alluvial Offshore Limited (FAOL) was contracted by Fugro Seacore Ltd on behalf of DONG Energy Power UK Limited to perform a geotechnical investigation for the proposed West of Duddon Sands Offshore Windfarm. The site investigation was performed to provide soils information that would assist in the geotechnical investigation associated with the survey. The purpose of this geotechnical site investigation is to provide high quality, fit for purpose, geotechnical data in a timely and cost-effective manner. The geotechnical investigation shall provide sufficient and adequate information about soil strata, strength, and deformation parameters to perform a detailed design of the wind turbine foundations. The foundations may be Mono piles (MP) or Suction Bucket Foundations (SBF) for the wind turbines, whereas a jacket pile structure (JPS) is anticipated for the substations. Phase 1 comprised 163 Piezocone Penetration Tests (PCPT), including extra attempts due to early refusal, at 118 turbine locations, 1 substation locations, and 21 extra locations. Phase 2 comprised 96 PCPTs, including extra attempts due to early refusal, at 86 turbine locations. The programme of in situ testing was performed in two phases. Phase 1 was performed from 29th May to 25th June 2010. Phase 2 was performed from 29th July to 25th August 2010.