Cross River (of which its native name is Oyono) is the main river in southeastern Nigeria and gives its name to Cross River State. It originates in Cameroon, where it takes the name of the Manyu River. Although not long by African standards its catchment has high rainfall and it becomes very wide. Over its last 80 kilometres (50 mi) to the sea its flows through swampy rainforest with numerous creeks and forms an inland delta near its confluence with the Calabar River, about 20 kilometres (12 mi) wide and 50 kilometres (31 mi) long between the cities of Oron on the west bank and Calabar, on the east bank, more than 30 kilometres (19 mi) from the open sea. The delta empties into a broad estuary which it shares with a few smaller rivers. At its mouth in the Atlantic Ocean, the estuary is 24 kilometres (15 mi) wide.