Port Nolloth, town and Atlantic port, Northern Cape province, South Africa, in the hot, arid Namaqualand south of the Namibia border. It was founded in 1855 to serve as a harbour for the copper mines in the vicinity, especially those at Okiep, to which it was connected first by rail and later by road. The town declined in the early 1900s but revived with the discovery of alluvial diamonds in the area in 1926. The harbour was deepened and enlarged in the 1970s and diamond mines continue to operate in the area. There are also rock-lobster canning factories in the town. Pop. (2001) 4,652.