This project has been undertaken by Subacoustech Environmental Ltd for DONG Energy to meet the requirements set out in FEPA consent 33723/08/0, specifically clause 9.35. It describes a series of underwater noise measurements undertaken at the Gunfleet Sands Offshore Wind Farm site during installation of the first four monopile foundations. The results have been interpreted in terms of the potential impact this noise may have on marine species based on linear unweighted metrics and also on the level of noise above hearing threshold (dBht) for the species considered. Measurements were undertaken along four transects extending approximately to the North, South, East and West of the wind farm site. These transects covered different areas and varying bathymetry of the surrounding region in order to best characterise the likely impact of the noise in the region. Measurements were carried out between the 10th October 2008 and 27th October 2008.