Portland Harbour (Port Code:GBPLB) is the fourth largest as of 2016 man-made port in the world. It is located beside the Isle of Portland, Dorset, on the south coast of England. Construction of the harbour began in 1849; when completed in 1872, its 520-hectare (1,300-acre) surface area made it the largest man-made harbour in the world, and remains one of the largest in the world today. It is naturally protected by Portland to the south, Chesil Beach to the west and mainland Dorset to the north. It consists of four breakwaters — two southern and two northern. These have a total length of 4.57 km (2.84 miles) and enclose approximately 1,000 hectares (2,500 acres) of water.
Commercial activities on the water include specialist diving services for vessels and repairs & maintenance as well as a bunkering (fuelling) station. The port is used by all nature of vessels from commercial ships such as bulkers, tankers, container carriers car carriers, survey and Reefers etc. to British and foreign naval vessels. Commercial activities on the land of the dock estate include fuel storage, natural gas storage, several engineering facilities and a shell fish specialist.
The Portland Harbour Revision Order 2010 provides for the creation of new berths and hardstand areas at the port in order to allow increased commercial activities over the next 50 years. These new facilities have been identified as part of a master plan and business strategy developed by Portland Port. The development is designed to increase berthing opportunities and provide more operational land.