Portland Harbour is located beside the Isle of Portland, off Dorset, on the south coast of England. It is one of the largest man-made harbours in the world. With harbour is naturally protected by Portland to the south, Chesil Beach to the west and mainland Dorset to the north. The harbour consists of four breakwaters — two southern and two northern. These have a total length of 4.57 kilometres and enclose some 520 hectares.