river in eastern Guyana that rises in the forests of central Guyana and flows northward without important tributaries for 215 miles (346 km) to the Atlantic Ocean at Georgetown. Its narrow estuary and rapid flow keep clear a direct channel of 16–20 feet (5–6 m) to the ocean. Oceangoing steamers ascend 65 miles (105 km) to Linden for bauxite; smaller ships reach Malali, 25 miles (40 km) farther upstream; beyond lie numerous rapids. Its name is that of the old Dutch colony of Demerara, which joined with Essequibo and Berbice in 1831 to become British Guiana (from 1966 the independent republic of Guyana).