Under the name ESI Noise, the Port of Rotterdam Authority will be giving vessels a financial discount, on the basis of an internationally accepted standard, if the amount of noise produced by the vessel when moored has been made transparent. The noise report must be drawn up according to the international Neptunes protocol. The resulting score is adopted by the Environmental Ship Index. In Rotterdam, vessels can now receive a discount of EUR 312.50 per visit up to a maximum of EUR 1,250 per year for having an ESI noise report. This discount scheme will be valid in any event until the end of 2023.The incentive is in line with the Port of Rotterdam Authority's policy to develop the port sustainably in harmony with the environment. Seagoing vessels are currently only subject to noise requirements in terms of working conditions on board, but not in terms of noise production impacting the residential area and the environment. By means of the incentive based on ESI noise, the Port of Rotterdam Authority is drawing attention to the noise produced by vessels with regard to the surroundings.In addition to the incentive scheme for individual ships based on ESI noise, the Port Authority, in collaboration with the Municipality of Rotterdam, the Province of Zuid-Holland and DCMR Rijnmond Environmental Service, will soon be starting a regional measurement programme regarding the noise of moored vessels in general. ESI noise and the regional measurement programme are both contributing to increasing knowledge about the noise of moored vessels and to increasing national and international attention for this problem.Environmental Ship Index is an internationally accepted measure that, until now, has focused only on the air quality and climate-related emissions of seagoing vessels. The new ESI noise index also reflects the performance of vessels in terms of noise.