One river, six names
Every traveller who has heard of the Mekong knows it as a single river. In practice it is measured, named and lived on differently at almost every stage of its course. The full run from its high, remote source on the Tibetan Plateau down to the South China Sea comes to roughly 4,350 kilometres by the figure most commonly used, though sources that trace the furthest headwater push that closer to 4,900 kilometres. The river’s uppermost reaches simply aren’t agreed on to the kilometre, and rather than pick a single number, it’s more honest to give the range. What is agreed on is the basin: about 795,000 square kilometres of catchment spread across six countries, feeding one of the most productive freshwater fisheries on the planet.
The river changes name at nearly every border it crosses. In China it’s the Lancang. Cross into Laos or Thailand and it becomes the Mae Nam Khong, the word that gave English its ‘Mekong’. In Cambodia it’s the Tonle Thom, the great river. By the time it reaches Vietnam and fans out into its many mouths at the coast, it’s the Cuu Long, the Nine Dragons, a name drawn from the nine channels that once carried it to the sea. Six countries share its length, China, Myanmar, Laos, Thailand, Cambodia and Vietnam, though nearly all Mekong travel happens across the last four. More than 1,200 fish species live in the river, the basin’s fisheries land around 2.6 million tonnes of catch a year, and something close to 70 million people depend on it directly for food, water or a living. Few rivers anywhere carry that much weight for that many people.
Tonle Sap and the reversing river
Nowhere on the river does something as strange as what happens at Phnom Penh each year. From roughly June to November, the Mekong’s flood season, the river rises high enough at the point where it meets the Tonle Sap river that the smaller river is pushed backwards, reversing direction and pouring into Tonle Sap lake instead of draining out of it. For months the lake becomes Southeast Asia’s largest natural flood reservoir, several times its dry-season size, before the current turns again as the dry season sets in and the lake drains back out toward the delta. It’s one of the more genuinely unusual pieces of hydrology anywhere in the world, and it is the reason the lake supports one of the richest inland fisheries on the continent.
When to go
There’s no single best month for the whole river, because its seasons run in different directions depending on where you are on it. Downstream, the flood season runs roughly June to November, filling the Tonle Sap and swelling the delta’s canals. In the delta itself, the flood-water season proper, when low fields and back roads sit under water and a boat becomes the practical way to get around, concentrates into September to November. The dry season, December to April, is the opposite story. It’s when the Irrawaddy dolphins at Kratie are easiest to see, since low water concentrates them in the Kampi pool, but it’s also when levels elsewhere on the river drop enough that some cruise operators shift their boarding points, particularly on the Cambodian side. Saltwater intrusion in the Vietnamese delta peaks late in this cycle, usually from late March into April, as low river flow lets the tide push further inland than at any other point in the year.
A quick way to think about it
- June to November: flood season downstream, and the Tonle Sap reversal is underway
- September to November: the delta’s flood-water season, best for its canals and back-water villages
- December to April: the dry season, and the best window for dolphin-watching at Kratie
- Late March to April: peak saltwater intrusion in the delta, and typically the lowest water on the river
Where the Mekong takes you next
The easiest way to plan a Mekong trip is to pick a stretch of river rather than a single city. Below is most of what this site is built around, from full cross-border journeys down to the single-country places they’re made of.
Plan your Mekong trip
Most of what’s above is built to be combined. Tell us how many days you have and which countries you’d like to cross, and we’ll put together an itinerary that follows the river rather than a fixed package.