Battering surf and shifting sand banks characterize the entire length of the shoreline. The Ras Nouadhibou (formerly known as Cap Blanc) peninsula, which forms Dakhlet Nouadhibou (formerly Lévrier Bay) to the east, is long and 13 km wide. The peninsula is administratively divided between Western Sahara and Mauritania, with the Mauritanian port and railhead of Nouadhibou located on the eastern shore. Dakhlet Nouadhibou, one of the largest natural harbours on the west coast of Africa, is long and wide at its broadest point. Fifty kilometres southeast of Ras Nouadhibou is Arguin. In 1455 the first Portuguese installation south of Cape Bojador (in the present-day Western Sahara) was established at Arguin. Farther south is the coastline's only significant promontory, -high Cape Timiris. From this cape to the marshy area around the mouth of the Senegal River, the coast is regular and marked only by an occasional high dune.