Is the Río de la Plata rough? What to expect on the crossing
Sometimes, mostly when the wind blows along the river. The Buenos Aires to Colonia crossing is 27 miles and takes about 1 hour 10 minutes with Colonia Express and 1 hour 15 minutes with Buquebus, over water that averages 4 meters deep along the route. A sudestada, a cold wind from the south to the southeast, can raise strong waves, and Wikipedia's article on it says it is most frequent and intense from July to October.
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Estuary · Argentina and Uruguay · Reputation among passengers: mixed: commonly reported as uncomfortable in the wrong conditions.
- Low
- Moderate
- High
- Very high
Roughness summarises typical reported conditions for this crossing, not a forecast for any given sailing.
Wind along the river's axis over shallow water
In the Nausea Index table of the 121 sea crossings we cover, the Río de la Plata is rated manageable, one of 81 in that band, with 40 rated higher. Full table: the roughest sea crossings, ranked.
Key facts
- The Río de la Plata is a estuary, and passenger reports place it in the moderate roughness band.
- The mechanism behind that reputation: Wind along the river's axis over shallow water.
- It is also known as River Plate.
Why does the Río de la Plata get rough?
The Río de la Plata is a funnel-shaped estuary about 290 kilometers long that widens from about 2 kilometers at its source to about 220 kilometers at its mouth, and Colonia Express puts its average depth along the Buenos Aires to Colonia route at 4 meters. When a sudestada, a cold wind from the south to the southeast, keeps blowing for several days, the axis of the river lines up with the wind, which raises the water level on the Argentine coast and gives strong waves. A sudestada usually ends when the wind turns to the southwest and a pampero takes over. The pampero comes with a cold front, often with squall lines and a sharp drop in temperature.
When is the Río de la Plata roughest?
Wikipedia's article on the sudestada says it can happen at any time of year and is common from April to December. It is most frequent and intense from July to October. Its article on the pampero says that wind is frequent in the austral winter and also happens in summer.
Where to be on board
Front to back
- Bow (front)Avoid
- MidshipBest
- Stern (aft)OK
The crossing: 1 hour 10 minutes to 2 hours 45 minutes
Roughest stretch: The open river between the two ports
Midship on a low deck, with a view of the horizon. The Colonia crossings take about 1 hour 10 minutes to 1 hour 15 minutes.
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The crossings that cross it
| Route | Typical duration | What to know |
|---|---|---|
| Buenos Aires to Colonia (Colonia Express) | about 1 hour 10 minutes | The operator lists 27 miles (50 km) from port to port. |
| Buenos Aires to Colonia (Buquebus) | 1 hour 15 minutes | The Buquebus booking page lists 1h 15 min on its ship Silvia Ana. |
| Buenos Aires to Montevideo (Buquebus) | 2 hours 45 minutes | The Buquebus booking page lists 2h 45 min on its ship Francisco, against 4 hours by ship to Colonia and bus to Montevideo. |
What helps on this crossing
- Watch the wind direction. The wind to avoid is a sudestada, a cold wind from the south to the southeast, which lines up with the river and raises strong waves.
- If you can choose, the shorter crossing is the easier one: Colonia Express lists about 1 hour 10 minutes and Buquebus 1 hour 15 minutes to Colonia, against 2 hours 45 minutes on the Buquebus ship to Montevideo.
- Sit midship on a low deck, keep your eyes on the horizon and put your phone away.
For the full toolkit see the seasickness guide, or what to do once it has already started. For what the trials actually say about the oldest trick on that list, see the verdict on looking at the horizon. If the rocking follows you ashore afterwards, that is land sickness, which is normal, and it passes.
Frequently asked questions
Is the Río de la Plata rough in August?
August sits in the main sudestada season: Wikipedia's article says that wind is most frequent and intense from July to October. A sudestada can raise strong waves when it lines up with the river, so check the wind forecast for a direction from the south to the southeast before you go.
Is the Río de la Plata rough in January?
January is outside the main sudestada months, which the article gives as April to December, although a sudestada can happen at any time of year. The pampero also happens in summer, with short storms and a sharp drop in temperature.
Is the Buenos Aires to Colonia ferry rough?
It depends on the wind. The crossing is 27 miles and takes about 1 hour 10 minutes with Colonia Express and 1 hour 15 minutes with Buquebus, over water that averages 4 meters deep along the route. The wind to watch is a sudestada, from the south to the southeast.
What is a sudestada?
A cold wind from the south to the southeast that is common over the Río de la Plata. If it blows for several days, the river's axis lines up with the wind, which raises the water level on the Argentine coast and gives strong waves. It usually ends when the wind turns to the southwest and a pampero takes over.
Other crossings
Sources & further reading
Sea conditions described here are typical patterns drawn from published marine and operator information as of July 2026, not a forecast: conditions on any given sailing depend on the weather that day, and any month can deliver a calm crossing or a bad one. Route and operator names are trademarks of their respective owners; Dizzout is not affiliated with or endorsed by them. Seasickness sensitivity varies from person to person; this page is informational and not medical advice.