Sisimiut, the second largest settlement of the country is the northernmost town with an ice free harbour. It is very important for the fishing industry of the country. Its harbour consists of two main quays, the Atlantic and the Fisher. These facilities have been outstripped due to the rapidly increase in number of calls and volume of TEU per year mainly during 2004 to 2006. With this reasoning, a need of an extension of the harbour has become real, and this Thesis is going to start its study with the analysis in two different fields: on-shore and off-shore. The on-shore is mainly studied to characterize the rock mass structure and its material. The structure of the rock mass is needed for tunnelling operations, which are going to provide a space used as a warehouse, by Royal Greenland. This has been studied on-site and its safest orientation was 172º clockwise from the North. The material found in the area has been Charnockite (which is similar to granite). The off-shore part of study includes an extraction of sediment samples and a scan of the sea bed. The first operation has been carried out by a mechanic grab and has ended up with an asymmetric distribution of sediments in Sisimiut Bay. In the front coast, very muddy sediments are accumulated, which entailed shallow depths. On the contrary, in the coastline where the current harbour lays nowadays, larger depths have been found as well as a more rocky sea bed. Continuing this first interpretation, a numerical analysis of the wave dynamics, generated by wind, with a fetch of around 400 km is set-up. For its computation, the worst case of water level has been implemented together with the worst wind direction and the worst speed acting constantly during 24h in the whole domain. The main significant results have been: Significant Wave Height≈2.3 meters and Mean Wave Period≈8 seconds. The wave direction tends to lead the wave trains to the innermost part of the Bay. In the last part of this Thesis, the Final Design, the best location for the extension is thought to be in the Atlantic and Fisher quay, distributing the total berth length into two different parts. On one hand, the Atlantic quay is thought to be focused just on container cargo handling. Its extension will increase more than 1.5 times the area of the current quay. On the other hand, the Fisher quay is going to be divided in two different alienations, the first one for the trawlers cargo handling, which will double its actual surface, and the other one, totally new, for passenger ships calls, extending an open berth along the coastline to the left. Finally the anchorage area has not represented a problem due to sufficient space on the Bay, or in unexpected conditions, placed off-shore.