The Mekong is the 10th-longest river in the world and the seventh-longest in Asia, at about 4,350 kms (2,703 mi).
It runs from the Tibetan Plateau through southern China, Burma, Thailand, Laos, Cambodia, and Vietnam.
The earliest known settlements along the Mekong River date from 2100 BCE.
All the countries through which the Mekong runs, except China and Burma, are members of the Mekong River Commission, which aims to promote sustainable management and development of water-related resources for its members through research and policy advice.
More than 1,200 species of fish have been identified along the course of the river.
One species of freshwater dolphin, the Irrawaddy dolphin (Orcaella brevirostris), was once common in the whole of the Lower Mekong but is now very rare.
The endangered Siamese crocodile (Crocodylus siamensis) has been reported along the Mekong but is very rare.
The two greatest environmental concerns facing the river are the building of hydropower dams and blasting of rapids to make the river more navigable to larger ships.
Dams on the Mekong are criticized on grounds of cost, damage to the environment, and forced relocation of residents.
Only three dams have been built on the Mekong, all of which were built by China. China is considering building another 12 dams.
Since the building of the first Chinese dam, many species have become endangered including the Mekong dolphin and manatee. Water levels have meanwhile dropped, leaving boats stuck, and fishing catches have diminished.
Increased water flow, which could lead to serious flooding, also presents a threat to downstream communities as China blasts rocks and sandbars in less navigable areas of the Mekong.
Balls of light are observable at times rising from the water's surface in a stretch of the river near Vientiane in Laos or Nong Khai in Thailand, which are referred to as Naga fireballs. Locals attribute the phenomenon to Phaya Naga or Mekong Dragons.
Chinese: Láncāng Jiāng
Burmese: Mè‘kaung Myit
Khmer: Tônlé Mékôngk
Vietnamese: Sông Mê Kông
Lao: Mae Num Khôn
Thai: Mae Nam Khong