The report within this series has been prepared by Subacoustech Ltd for GLID TopCo Ltd. It describes a series of underwater acoustic measurements undertaken in and around the Lynn and Inner Dowsing Wind Farm sites, on the 16th, 17th and 18th February 2011 in accordance with FEPA licence requirements. The purpose of the measurement programme was to characterise any increase in the ambient subsea noise due to the presence of the operational wind farm, and to assess the range over which any increase in noise occurred. Underwater noise was recorded using specialist equipment developed by Subacoustech Environmental Ltd. This measured the underwater sound to levels well below sea state zero noise, and over the frequency range that covers both that required to characterise anthropogenic noise in the ocean, and the hearing response range of species of fish and marine mammals. Measurements were undertaken from a range of 10 m from an operational turbine, and along transect lines both inside and outside of the wind farm to a range of 10 km.