The Mekong is the great river of mainland Southeast Asia. It rises on the Tibetan Plateau, flows south through China, then forms borders and crosses countries all the way to the South China Sea. Reading its course on a map is one of the fastest ways to understand how Laos, Thailand, Cambodia and Vietnam fit together.
The six countries on its course
Following the current, the Mekong passes through or along:
- China, where it is called the Lancang and flows through deep gorges in Yunnan.
- Myanmar, along a short border stretch with Laos.
- Laos, which it crosses from north to south and where it passes the capital, Vientiane.
- Thailand, for which it forms long stretches of the border with Laos.
- Cambodia, where it meets the Tonle Sap river at Phnom Penh.
- Vietnam, where it splits into the many arms of the delta.
Upper and lower Mekong
Geographers often divide the river in two. The upper Mekong runs through China and is fast, narrow and steep. The lower Mekong begins where the river leaves China and crosses the plains and plateaus of Southeast Asia.
The lower basin has its own international body. The Mekong River Commission is an intergovernmental organisation for regional cooperation in the Lower Mekong River Basin, established in 1995 under the Mekong Agreement between Cambodia, Lao PDR, Thailand and Viet Nam. China and Myanmar, the two upstream countries, are not members of that agreement, which matters for decisions about dams and water flow.
The Golden Triangle
Where the Ruak river joins the Mekong, Thailand, Laos and Myanmar meet at a single point. This corner is known as the Golden Triangle. Today it is a viewpoint for travellers in northern Thailand, and the starting point of slow boat trips down the river to Luang Prabang in Laos.
Laos and the Thai border
Through northern and central Laos the Mekong is the main road. Luang Prabang, the former royal capital, sits at its confluence with the Nam Khan. Further south, the river becomes the border between Laos and Thailand for long stretches, and Vientiane faces Thailand across the water. Bridges known as Friendship Bridges link the two countries at several points.
The Khone Falls
In southern Laos, close to the Cambodian border, the river spreads into a maze of channels and islands known as Si Phan Don, the Four Thousand Islands. Just below them, the Khone Falls block the river with a series of cascades and rapids. They are the main reason the Mekong was never a continuous waterway from the sea to China, and they shaped colonial-era plans to navigate it.
The Tonle Sap, a river that changes direction
At Phnom Penh, the Mekong meets the Tonle Sap river, which links it to the large Tonle Sap lake in central Cambodia. During the monsoon, the Mekong rises so much that it pushes water up the Tonle Sap river and into the lake, which swells far beyond its dry season size. When the waters fall, the flow reverses and the lake drains back into the Mekong. This seasonal reversal feeds one of the most productive inland fisheries in the world and is celebrated in Phnom Penh with a water festival.
The Mekong Delta
Below Phnom Penh the river divides, and in southern Vietnam it fans out into the delta. In Vietnamese it is often called Cửu Long, the Nine Dragons, after its main arms. The delta is a flat land of rice fields, canals, orchards and floating markets, with towns such as Cần Thơ and Mỹ Tho. Ho Chi Minh City sits just north-east of it, on the Saigon river rather than on the Mekong itself.
Travelling along the river
- Slow boats run downstream from the Thai border at Huay Xai to Luang Prabang, with an overnight stop at Pakbeng.
- Kratie, in north-eastern Cambodia, is the place to look for the rare Irrawaddy dolphins that live in a few deep pools of the river.
- The delta is usually visited from Ho Chi Minh City or from Cần Thơ, by small boat through the canals.
Dams and seasons
The Mekong is shaped by the monsoon. Water levels are low in the dry season and high during the rains, which affects boat trips, fishing and farming. Dams built upstream in China and on the main river and its tributaries in Laos have changed those patterns, and the Mekong River Commission monitors water levels and floods for its member countries.
Reading the Mekong with neighbouring regions
The map of Southeast Asia shows the countries of the lower basin, and the map of the Himalaya covers the plateau where the river begins. The map of East Asia places Yunnan and the upper course in context. For another water body shared by many countries and run through a regional treaty, see the map of the Red Sea.
The Mekong River Commission publishes water level data, flood forecasts and its agreement on its official website.
