Plizio Visual Lab
Tonle San River
Plizio editorial teamData Sources
River
Weather…
Water temperature…
The Tonle San, also known as the Sesan River, is a major tributary of the Mekong River originating in the Central Highlands of Vietnam. It flows westward through the Cambodian provinces of Ratanakiri and Stung Treng, eventually merging with the Srepok and Sekong rivers in the '3S' river system. The river is a lifeline for thousands of people, particularly indigenous ethnic minorities who rely on its fish stocks and fertile banks for agriculture. In recent years, the Sesan has been the subject of significant environmental concern due to large-scale hydropower projects, such as the Yali Falls Dam in Vietnam and the Lower Sesan 2 Dam in Cambodia, which have altered its natural flow and impacted fish migration routes. Geographically, the river is known for its winding course through dense forests and its role in replenishing the Mekong's sediment levels. Its waters support a high diversity of aquatic species and provide critical habitat for waterbirds along its forested stretches.
- Location: Cambodia
- Nearby: Stung Treng (24 km)
Best time to visit & climate
The most pleasant time to visit is Jan, Feb, Dec.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg °C | 26 | 28 | 30 | 31 | 30 | 29 | 28 | 27 | 27 | 28 | 27 | 26 |
| Rain mm | 3 | 2 | 16 | 36 | 96 | 152 | 202 | 218 | 167 | 83 | 23 | 8 |
📋 Practical info
Getting there
The river flows through northeastern Cambodia and is best accessed from towns like Banlung or Stung Treng. Transportation in the area is mostly conducted via motorized long-tail boats.
Best season
The dry season (November to April) is well-suited for boat tours as the current is calmer. During the rainy season, the water level rises drastically, and the river becomes much more turbulent.
Terrain & paths
The river landscape is characterized by dense jungle and small riverside settlements. The terrain at landing points can be muddy and steep, especially when the water level is receding.
What to bring
Insect repellent, sun protection, and a waterproof dry bag for valuables are essential for boat trips. Wear lightweight, quick-drying clothing that also provides protection from the sun.
Parking
In larger towns like Stung Treng, parking is available at guesthouses. At small riverside landing points, there are few secure spots; it is better to use local transport services to get there.
Safety
Always wear a life jacket while on the boat. Be cautious on the riverbanks and ensure you have an adequate supply of clean drinking water while traveling through this remote region.
Time needed
A typical boat tour lasts between 3 and 6 hours. Multi-day trips upstream to remote villages are also possible and offer deeper insights into the pristine nature and local cultures.
Geography
Facts
- Source: Central Highlands, Vietnam
- Mouth: Mekong River
- River group: Part of the '3S' system
- Major dam: Lower Sesan 2 Dam
- Key provinces: Ratanakiri and Stung Treng
- Hydrology: Significant monsoon-driven flow
Explore nearby
Notable places around
Route planner — Car & Motorhome
Where do you start? We build the route here, with stops and country notes along the way.
Vehicle
Only stops with (optional):
© OpenStreetMap contributors · OpenRouteService
Sights nearby
Frequently asked questions
Where does the Tonle San flow?
It flows through northeastern Cambodia and is a tributary of the Mekong.
Can you go kayaking on the river?
Yes, guided kayaking and boat tours are offered near Banlung.
Are there hydroelectric dams on the river?
Yes, several dams affect the water level and local ecology.
Which ethnic groups live along the riverbanks?
Various indigenous minorities, such as the Jarai, live in villages along the river.
Is the river suitable for fishing?
Yes, it is rich in fish and an important food source for local residents.
Tonle San River: where is it located?
Tonle San River is located in Cambodia.
Tonle San River: when is the best time to visit?
The most pleasant time to visit is Jan, Feb, Dec.
Tonle San River: why is it worth visiting?
The Tonle San, also known as the Sesan River, is a major tributary of the Mekong River originating in the Central Highlands of Vietnam.
Explore with Plizio
Discover more places in Asia
More places in Cambodia →
Nearby cities
Stung Treng
Located near the border with Laos, this northern town is an important transport hub where the Sekong, Sesan, and Mekong rivers converge.
Don Khon
The quieter sister island of Don Det, known for historic French ruins and impressive waterfalls.
Kratie
This relaxed town on the banks of the Mekong is the best destination in Cambodia to observe the rare Irrawaddy dolphins in the wild.
Muang Khong
Muang Khong is the main town on the island of Don Khong in the 4000 Islands region.
Si Phan Don (4000 Islands)
An idyllic archipelago in the Mekong River, famous for its thundering waterfalls and an extremely laid-back lifestyle.
Tad Yuang
A picturesque and easily accessible waterfall on the Bolaven Plateau, perfect for picnicking and relaxing.
Snuol
Snuol is a vital trading hub in eastern Cambodia and a historically significant site of the Cambodian resistance.
Champasak
Champasak is a historic town in southern Laos.
Pakse
Pakse is the capital of Champasak Province and a major commercial center.
Tây Ninh
The center of the Cao Đài religion, home to the colorful and ornate Cao Đài Holy See.
Salavan
Salavan is a provincial town in southern Laos.
Bavet
Bavet is the largest border town with Vietnam on the direct route from Phnom Penh to Ho Chi Minh City, experiencing rapid growth due to s…
History & landmarks
Nature
More places
🗺️
Lower Sesan 2 Dam
A massive hydropower project that meets a significant portion of Cambodia's electricity needs.
🗺️
Xe Pian National Park
An extensive protected area in the far south, encompassing vast wetlands and dense forests, bordering Cambodia.
Kampi Dolphin Habitat
One of the best places in Cambodia to observe the rare Irrawaddy dolphins in the wild on the Mekong River.
🗺️
Xe Pian National Protected Area
An extensive protected area with wetlands and forests, housing an immense diversity of bird species.
Dong Hua Sao National Park
A protected area descending from the cool heights of the Bolaven Plateau down into the hot lowlands of the Mekong Valley.
🗺️
Virachey Mountains
An inaccessible mountain region on the border with Laos and Vietnam.
Dong Hua Sao National Protected Area
A nature reserve in the south where steep cliffs and deep forests provide habitat for wild Asian elephants and hornbills.
Paksong Tea Plantations
Extensive tea plantations in the cool climate of the Bolaven Plateau, where some of the best teas in Southeast Asia grow.