Choosing a Mekong river cruise
How to choose
High and low water, explained
The Mekong rises and falls by several metres over the year, and that one fact decides whether a ship can reach the Tonle Sap lake, whether a delta stop is reachable under its bridges, and what the last day of a seven-night cruise looks like. Here is what operators publish, and where they disagree.
What the operators say
| Source | High water | Low water | Effect stated |
|---|---|---|---|
| Aqua Expeditions | Mid-August to November | December to mid-August | In low water vessels cannot reach the Tonle Sap; guests fly Phnom Penh to Siem Reap at no extra cost |
| Pandaw guide (main text) | August to November | December to July | In high water ships cross the lake to Siem Reap; in low water the river is too shallow and the journey is by road |
| Pandaw guide (FAQ) | August to October | — | Same guide, different months |
| Pandaw 2026 product PDF | October–November | — | Low bridges may block the way into Chau Doc; Long Thuan replaces it |
| A reseller (Vietnam Paradise Travel) | July to December | January to June | Transfers by riverboat or van to and from Siem Reap, about 5–6 h |
The pages do not explain why their months differ, and the 2025 flood figures show how much one year can differ from another. When a ship's own page and its FAQ disagree, we ask the operator about your sailing rather than pick one.
Sources: Aqua Expeditions — Mekong river cruise; Pandaw — The Classic Mekong guide, 4 May 2026; Pandaw — Saigon to Phnom Penh product PDF (new for 2026); Ministry of Agriculture and Environment, 3 Oct 2025 — 2025 Mekong flood; Vietnam Paradise Travel — Indochine II page (reseller, undated) · checked .
Why the river changes so much
Pandaw cites the Mekong River Commission: the river's volume can increase tenfold at the peak of the wet season, and levels shift by several metres between seasons. The Tonle Sap river, which links the lake to the Mekong at Phnom Penh, is the stretch that becomes too shallow for cruise ships in the dry months.
Downstream in the delta the flood arrives later. In 2025 Vietnam's agriculture ministry forecast the main flood peak at Tan Chau and Chau Doc for 8 to 13 October, with riverside streets in Can Tho flooding at peak tides in October and November.
Sources: Pandaw — The Classic Mekong guide, 4 May 2026; Ministry of Agriculture and Environment, 3 Oct 2025 — 2025 Mekong flood · checked .
What changes on each kind of cruise
| Cruise | Low water (about December to July) | High water (about August to November) |
|---|---|---|
| Delta boat, 1–2 nights | Little change; boats stay on Vietnamese rivers and canals | Upper delta flooded; Pandaw notes possible bridge closures near Chau Doc in October–November |
| Saigon to Phnom Penh | Runs; the stretch to Phnom Penh stays navigable on the itineraries we read | Runs; a Chau Doc stop may be replaced |
| Saigon to Siem Reap, ships that try for the lake | River ends short; road to Siem Reap, or Aqua's flight | Ships can cross the lake to the Siem Reap side |
| Ships ending at Kampong Cham (Viking, Scenic, Victoria Mekong) | Road to Siem Reap | Road to Siem Reap |
Pandaw also notes that Kampong Chhnang is reached 'by ship or by coach depending on water levels', and that sandbars and sudden changes in level can alter any day's plan. Its published itineraries are 'indicational only'.
Sources: Pandaw — Saigon to Phnom Penh product PDF (new for 2026); Pandaw — The Classic Mekong guide, 4 May 2026; TravelVietnam.com — Pandaw low-water programme (reseller); Aqua Expeditions — Mekong river cruise; Viking press release, 14 Nov 2023; Cruiseline.co.uk — Scenic Spirit sample departure (agent); Wendy Wu Tours AU — Victoria Mekong · checked .
Delta weather, month by month
| Month | Rain (mm) | Rainy days | Mean high (°C) |
|---|---|---|---|
| January | 10 | 2 | 30.2 |
| February | 3.8 | 0.8 | 31.2 |
| March | 15 | 1.8 | 32.7 |
| April | 42 | 5.6 | 33.9 |
| May | 223 | 16.4 | 33.2 |
| June | 310 | 19.9 | 32.0 |
| July | 336 | 21.5 | 31.4 |
| August | 338 | 21.6 | 31.2 |
| September | 451 | 22.1 | 31.1 |
| October | 301 | 21.8 | 31.0 |
| November | 137 | 13.6 | 30.7 |
| December | 42 | 6.5 | 29.7 |
Climate normals for Can Tho, published on Wikipedia from Vietnamese building-science data. VNAT suggests December to April as the time for boat trips and May to August for fruit. Dengue in Vietnam peaks from June to October, so pack repellent for shore stops.
Sources: Wikipedia — Can Tho (climate table); Vietnam National Authority of Tourism — Mekong Delta; WHO Viet Nam — dengue · checked .
What we check for your dates
For any enquiry that involves the Tonle Sap stretch, we ask the operator three things for the specific sailing: where it expects the river part to end, how guests reach Siem Reap from there, and how long that transfer takes. For delta boats in October and November we ask whether the route near Chau Doc is affected. The answers go into the comparison we send, next to the fare, so that two sailings in different months are compared on what they will actually do.
Choosing your month
| If you travel in… | Consider |
|---|---|
| December to April | A delta boat in the dry season, or Saigon to Phnom Penh. A ship to Siem Reap will finish by road or air. |
| May to July | The same as above, with afternoon rain. Orchards in fruit. |
| August to November | The window for reaching the Siem Reap side by water on ships that cross the lake; check Chau Doc access in October and November. |
Then compare the ships on the seven-night page or the three-night page, and read about the end points under Siem Reap and the Tonle Sap.
Common questions
Questions travellers ask most
Is low water a reason not to cruise?
No. The delta, the border, Phnom Penh and much of the Tonle Sap river are still on the water. What you lose is the arrival at Siem Reap by boat.
Why do operators give different months?
Their pages do not say. Pandaw's guide even gives two different ranges on the same page, so we ask the operator about your specific sailing.
Does high water make the cruise rougher?
The operators we read do not say so. What they do note is changed stops: bridges near Chau Doc in October and November, and some villages reachable only at certain levels.
Can we see the flood in the delta from a delta boat?
The upper delta floods from about September to November. A two-night cruise towards Chau Doc goes furthest into it, subject to the bridge limits Pandaw mentions.
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The four kinds of Mekong cruise and the boats that run each one.
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Tell us which cruise you are weighing up
A month, how many are travelling and whether you lean towards a delta boat or a ship into Cambodia are enough to start. We reply by email with the boats that sail your dates and the fares their operators show that day.