Tonle Sap is a lake that fills from the wrong end. For about half the year the Tonle Sap River drains it into the Mekong as any tributary would; then, in the wet season, the Mekong rises so high that the river reverses direction and pushes water back up into the lake, according to the Mekong River Commission. The villages you visit from Siem Reap are built around that swing.
Why does the Tonle Sap River reverse?
The Mekong Delta downstream cannot carry the full wet-season flood of the Mekong, so the water backs up into the Tonle Sap River. When the Mekong's level passes the Tonle Sap River's, the current turns round. When the Mekong falls at the end of the wet season, the flow returns to normal and the lake drains back out. Over a whole year, the Tonle Sap system supplies about 9 percent of the Mekong's mean annual flow, the commission estimates.
The Mekong River Commission's 2010 State of the Basin report gives the scale: the lake grows about six-fold, from 2,500 to 15,000 square kilometres, and its volume from 1.5 cubic kilometres to between 60 and 70. That is 40 to 47 times more water in the lake at its peak. A 2019 study in the journal Water puts the typical range at 2,600 to 12,000 square kilometres, with average depth rising from under 2 metres to over 10, and places the reversal in the flood season between June and October. UNESCO's biosphere reserve page says the lake can expand up to five times. The figures differ because each flood is a different size; the pattern does not.
This reversal is also why people live here. UNESCO describes the lake as one of the world's top four fishery production areas, and the flooded forests that appear each wet season are, in the Cambodian government's words, nurseries for fish, protected in a strict zone where settlement and commercial use are banned. Houses stand on tall stilts or float, built for water that rises and falls by metres each year.
Which Tonle Sap village should you visit?
Three lakeside communities are commonly reached from Siem Reap. They are not interchangeable.
| Village | Distance from Siem Reap | What it is | Best season for it |
|---|---|---|---|
| Kampong Phluk | Just over 10 km | Three villages of stilt houses, flooded forest, community-run homestays | High water, when boats run under the forest canopy |
| Kampong Khleang | About 45 km | A large fishing and fish-processing community with boat and canoe trips | Either; the dry season shows fish processing and the full height of the stilts |
| Chong Kneas | Not stated in official sources we read | A buffer-zone town at the lake's edge, where UNESCO notes a large harbour under construction | We could not find current official visitor information |
Kampong Phluk: the high-water classic
Kampong Phluk, in Prasat Bakong district, is just over 10 kilometres from Siem Reap town. In a July 2026 report on a World Bank assessment, Cambodia's state news agency counted 1,106 families, or 3,820 people, in three villages, with houses raised 6 to 10 metres above the ground and a cycle of six dry months and six flooded months. About 65 percent of residents fish and 35 percent work in community-based ecotourism.
The same agency calls the commune a tourism hotspot especially from May to October, when the lake rises and the flooded forest comes back to life. In the dry months the forest floor is exposed and the houses stand on bare stilts; that is interesting in its own right, but it is not the boat-through-the-trees trip most people picture. We found no official statement on how late in the dry season boats still reach the village, so ask your hotel or the community before booking a boat-based visit in the later dry months.
Kampong Khleang: bigger, further and working
Kampong Khleang, in Sotr Nikum district, is about 45 kilometres from Siem Reap. More than 85 percent of its nearly 1,800 families depend on fishing, including making prahok (fermented fish paste), smoked fish and dried fish. It is organised as a Natural Tourism Community offering canoe tours, sunset boat trips through the floating village, homestays and local meals.
Fish processing is the reason to consider it in the dry season. A February 2025 report described 30 families specialising in smoked fish, with visitors able to watch the fish being skewered, sun-dried and smoked.
Chong Kneas: check before you go
UNESCO lists Chong Kneas as one of four towns in the biosphere reserve's buffer zone and notes a large harbour under construction there. Beyond that, we could not find an official page describing current visitor arrangements or boat prices, so treat any offer as something to verify on the spot.
Who gets your boat fare?
Community-based tourism around the lake is a government policy, not only a marketing term. The Minister of Tourism also chairs a national committee for community tourism and ecotourism, and a Tonle Sap Ecotourism Network holds an annual forum of lake communities. At Kampong Phluk, the state news agency says residents earn fees from the services they provide, including homestays.
None of the official pages we read publishes boat prices for any village, so we do not quote the figures that circulate online. Before paying, ask who runs the boat and whether the fare goes to the community's tourism committee or to an outside operator; a homestay or meal booked with the community keeps more of the money local.
Choosing your month
If your dates are fixed, let them choose the village. From about May to October, pick Kampong Phluk for the flooded-forest boat ride. In the dry months, pick Kampong Khleang for fish processing and the full height of the stilt houses, or visit Kampong Phluk knowing you will see a forest on dry land. The lake is also a working fishery watched closely by the Tonle Sap Authority, which has monitored fish diversity since 2012 at communities including Kampong Phluk. Nets, fish traps and homes are people's livelihoods, so ask before photographing people or their houses.
If you are combining the lake with temples on the same day, plan the Angkor part first with our Angkor Pass guide.