On the instructions of RSKENSR Environment Limited, Osiris Projects were commissioned to carry out a pre-construction survey covering the proposed Barrow Offshore Wind Farm development site and associated cable and navigation routes. The main development site survey covered an area of approximately 9.8km². High-resolution side scan sonar and single beam bathymetry data were acquired along all survey lines, which were run at 100m centres, with cross lines at 500m centres, in order to accurately map the entire seabed within the wind farm development area. For the proposed cable route into Heysham, two parallel survey lines were run at 100m separation. For the navigation route into Barrow-in-Furness, four survey lines were run at 50m separation. Data acquisition took place during the period 29th March to 2nd April 2005, with survey works undertaken using the survey vessel MV ‘Lia’. The primary objective of the survey was to map seabed features and bathymetry within the wind farm area and along the associated cable and navigation routes, in order to establish the presence of any debris. This data will be used as ‘baseline’ information for comparison with further survey data, which will be collected after construction of the turbines and associated cabling has been completed.