The Tugela River (also known as Thukela) is the largest river in KwaZulu-Natal Province, South Africa. The river originates in the Drakensberg Mountains, Mont-aux-Sources, (itself the source of tributaries of two other major South African rivers, the Orange River and the Vaal River) and plunges 947 metres down the Tugela Falls. From the Drakensberg range the river meanders for 520 km through the KwaZulu-Natal midlands before flowing into the Indian Ocean. The total catchment area is approximately 29,100 square km. Land uses in the catchment are mainly rural subsistence farming and commercial forestry.

There are a number of large inter-basin transfer schemes responsible for transferring water from the Tugela basin across the escarpment into the Vaal River system. The main scheme is the Drakensberg Pumped Storage Scheme operated by Eskom. There is also the original pumping station at Jagersrus.

It has a number of tributaries coming off the Drakensbergs, including the Klip River (rising near Van Reenens Pass ), Mooi River and Buffalo (rising near Majuba Hill) rivers. Another northern tributary is the Sundays river, which rises in the Biggarsberg. It also receives the Ingagani (from the south-west) and the Blood River (from the north-east, named from the defeat of the Zulu king Dingane, on 16th December, 1838, by the Boers under Andries Pretorius, when the river is said to have run red with the blood of the Zulus).

It passes Bergville, and Colenso, the latter is a site of an important battle in the Boer War and for many years was the site of the first major power station in Natal. The power station was built by the South African Railways to electrify the railway line north from Pietermaritzburg. It was coal-fired and the cooling water came from the Tugela.

Below the Blood River is Rorke's Drift, a crossing point and another battle site, this time from the Anglo-Zulu War.

Below the Buffalo confluence the Tugela flows southeast in a deep channel between cliffs and valleys until it reaches the narrow coast belt. Its mouth is nearly closed by a sand bar, formed by the action of the ocean. The Tugela is thus not navigable.

About 10Km above the mouth are two historic forts, Fort Pearson and Fort Tenedos, built by the British in 1879, during the war with the Zulus, to guard the passage of the river. Generally fordable in the winter months, the Tugela is, after the heavy rains of summer, a deep and rapid river.

The Tugela formed a natural border between Zululand and Natal, until the British annexed Zululand on May 9, 1887.