The Walney Offshore Wind Farm is planned for a site approximately 20km off the Isle of Walney, Cumbria, covering an area with water depths of between 18m and 31mCD. This report has been prepared for DONG and their design consultants Niras. It sets out the predicted winds, waves, currents and water levels that will influence design. The report includes a comprehensive set of tables figures and appendices presenting the required data. The study builds on the work done previously by HR Wallingford for the nearby Barrow Offshore Wind Farm.