The Diamantina River is a major river in Central West Queensland and the far north of South Australia.

The river was named by William Landsborough in 1866 for Lady Diamantina Bowen (née Roma), wife of Sir George Bowen, the first Governor of Queensland.^[1] It has three major tributaries the Western River, Mayne River and Farrars Creek.^[3]

Rising north-west of Longreach in the Swords Range in Queensland, the river flows in a south-westerly direction through central Queensland and the Channel Country to form the Warburton River at its confluence with the Georgina River.^[4][5] In extremely wet years, the Warburton River flows as far as Lake Eyre.^[6] The length of the Diamantina River is approximately 900 km (560 mi), and the basin is approximately 157,000 square kilometres (61,000 sq mi),^[7] of which 140,000 square kilometres (54,000 sq mi) are used for agriculture.

Most of the basin of the Diamantina is very flat—even the highest points in the northeast do not reach 500 m (1,600 ft) above sea level and Lake Eyre itself is 16 m (52 ft) below sea level. Apart from a few streams near Winton (the largest town in the basin) almost all rivers in the basin flow southwestwards towards Birdsville. The Diamantina River has no main channel, rather it is a series of wide and relatively shallow channels.^[3] The major feature of the river's sluggish course is Diamantina National Park about halfway between Winton and Birdsville. Apart from the national park, almost all land in the basin is used for grazing cattle and sheep, though numbers fluctuate greatly and considerable skill is required on the part of graziers.

The variable drought and flood cycles of the area make the river ephemeral with many semi-permanent waterholes. The highest recorded flow rate of the river was at Birdsville in 1974 with 4,700 cubic metres per second (170,000 cu ft/s) was measured.^[8]

The Diamantina runs along the northern and eastern rim of a roughly circular zone measuring some 130 km across that has been identified by Geoscience Australia as a crustal anomaly. Proof is currently lacking as to the cause, but it is believed likely that the anomaly was caused by an asteroid strike that happened about 300 million years ago.^[9]

The river is ephemeral but floods periodically following heavy rainfall events in the catchment. During the floods of 1940 the mailman, Harry Ding, completed his round using a motorboat and Cooper Creek was measured at around 43 kilometres (27 mi) wide.^[12] In 1950 flooding covered some 7,770 square kilometres (3,000 sq mi), with the river described as a raging torrent 48 kilometres (30 mi) wide.^[13]

Karuwali (also known as Garuwali, Dieri) is a language of far western Queensland. The Karuwali language region includes the landscape within the local government boundaries of the Diamantina Shire Council, including the localities of Betoota and Haddon Corner.^[14]

• List of rivers of Australia
• Diamantina River ring feature