The Port of Rotterdam is expanding to meet the growing demand to accommodate large cargo vessels. The construction of Maasvlakte 2 (MV2) started in September 2008. One of the licensing conditions is the monitoring of the underwater sound produced during its construction, with an emphasis on the establishment of acoustic source levels of the trailing suction hopper dredgers (TSHDs) during their various activities: dredging, transport and discharge of sediment. TNO (Netherlands Organisation for Applied Scientific Research) Sonar and Acoustics carried out measurement and analysis activities for this monitoring. During an initial measurement campaign in September 2008, background measurements were performed in the absence of dredging. Source level and background sound measurements were made in the dredging area while MV2 dredging activities were underway in September 2009. In a final phase of the study, possible effects of underwater sound on marine fauna were considered for scenarios with and without dredgers. In this article, the principal results of the research are described and discussed in the context of the effects predicted in the Environmental Impact Assessment.