The Mekong is the Southeast Asian river ranked 12th by length that reaches the South China Sea.
The river rises on the Tibetan Plateau and is known as the Lancang Jiang in China. It then crosses or borders Myanmar, Laos, Thailand, Cambodia, and Vietnam before spreading through the Mekong Delta and reaching the sea.
Its seasonal flow is shaped by Himalayan snowmelt and monsoon rains. The Mekong is also a major source of fisheries, irrigation, transport, and fertile farmland. Dams and changing sediment flows have created serious ecological and political concerns across the basin.
A common mix-up is confusing the Mekong with the Salween or Irrawaddy, which are also major mainland Southeast Asian rivers but follow different courses and reach different seas. The Chao Phraya is Thailand’s principal river, but it is much shorter and drains into the Gulf of Thailand.