Darling, river, 1,702 mi (2,739 km) long, rising in the Eastern Highlands, NE New South Wales and SE Queensland, Australia, and flowing SW across New South Wales into the Murray River at Wentworth. It is the longest river in Australia. Although it receives numerous tributaries in its upper course, the Darling has dried up on several occasions. The river is used extensively for irrigation, and the combined Murray-Darling basin supports more than 40% of Australia's agriculture. It was explored in 1828 by Charles Sturt, an English explorer.