The Great Man-Made River is a network of pipes that supplies water to the Sahara Desert in Libya, from the Nubian Sandstone Aquifer System fossil aquifer.

It is the world's largest irrigation project.

According to its website, it is the largest underground network of pipes (2820 km) and aqueducts in the world. It consists of more than 1,300 wells, most more than 500 m deep, and supplies 6,500,000 m3 of fresh water per day to the cities of Tripoli, Benghazi, Sirte and elsewhere. The Libyan Leader Muammar Gaddafi described it as the "Eighth Wonder of the World."

In 1953, efforts to find oil in southern Libya led to the discovery of large quantities of fresh water underground. The Great Man-made River Project (GMRP) was conceived in the late 1960s and work on the project began in 1984. The project's construction was divided into five phases. The first phase required 85 million m³ of excavation and was inaugurated on 28 August 1991. The second phase (dubbed First water to Tripoli) was inaugurated on 1 September 1996.

The project is owned by the Great Man-Made River Project Authority and was funded by the Gaddafi government. Brown & Root and Price Brothers were responsible for the original design, and the primary contractor for the first phases was Dong Ah Consortium and the present main contractor is Al Nahr Company Ltd. This company was registered in England and Wales as a foreign company FC017848 until 31 July 2003.

The imported goods from several countries worldwide (such as Italy, Spain, Germany, Japan, etc.) destined to the construction of the GMR arrived by sea via the entry port of Brega (Gulf of Sidra).

The total cost of the project is projected at more than US$25 billion.