Is the Taiwan Strait rough? What to expect on the crossing
Yes in winter, and mostly no in late spring and summer. In wave reanalysis data (ERA5) the mean daily maximum wave height near Penghu is about 2.4 to 2.8 m from October to February, against about 1.1 m from May to July. The Budai fast boats to Penghu stop for the winter because of seasonal sea conditions.
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Strait · Taiwan · Reputation among passengers: has a long-standing reputation for rough passages.
- Low
- Moderate
- High
- Very high
Roughness summarises typical reported conditions for this crossing, not a forecast for any given sailing.
Northeast monsoon over a shallow strait
In the Nausea Index table of the 121 sea crossings we cover, the Taiwan Strait is rated rough, one of 34 in that band, with 6 rated higher. Full table: the roughest sea crossings, ranked.
Key facts
- The Taiwan Strait is a strait, and passenger reports place it in the high roughness band.
- The mechanism behind that reputation: Northeast monsoon over a shallow strait.
- Conditions are reported roughest in December.
- The calmest months are usually April, May, June, July, August and September.
- It is also known as Black Ditch.
Why is the Taiwan Strait so rough?
The Taiwan Strait is 126 km wide at its narrowest and almost entirely less than 150 m deep. The operator of the Kaohsiung to Penghu ferry says its wide hull keeps it less limited by sea conditions in the northeast monsoon than lighter fast boats. Taiji Star, which runs the Budai to Penghu catamarans, suspends the route for winter in line with seasonal sea conditions, and its 2026 notice gives 12 October as the start. The Penghu National Scenic Area Administration says sailings change with the season and the weather.
When is the Taiwan Strait roughest?
ERA5 data for 2000 to 2024 ranks December as the roughest month near Penghu, with January, November, February and October close behind, and May and June as the calmest. The Budai to Magong boats stop each winter, and the Penghu National Scenic Area Administration says that in winter only the Kaohsiung to Magong ship runs. The Penghu ferry's operator says its wide hull keeps it less limited by sea conditions in the northeast monsoon, and it refunds tickets in full within 30 days when weather stops a sailing.
| Roughest water in Jan | Roughest water in Feb | Roughest water in Mar | Roughest water in Apr | Roughest water in May | Roughest water in Jun | Roughest water in Jul | Roughest water in Aug | Roughest water in Sep | Roughest water in Oct | Roughest water in Nov | Roughest water in Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Rough | Rough | Mixed | Calm | Calm | Calm | Calm | Calm | Calm | Rough | Rough | Roughest |
Typical seasonal pattern, not a forecast. Any month can deliver a calm crossing or a bad one. Check the marine forecast for your sailing date. Select a month to see every sea and ferry crossing ranked for it.
Where to be on board
Front to back
- Bow (front)Avoid
- MidshipBest
- Stern (aft)OK
The crossing: 100 minutes to 6.5 hours
Roughest stretch: The open Penghu Channel between the two ports
Take a low seat or sleeper cabin near the middle of the ship. The Penghu ferry has sleeper cabins for the night sailing.
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The crossings that cross it
| Route | Typical duration | What to know |
|---|---|---|
| Kaohsiung to Magong (Penghu) | about 4.5 hours by day, about 6.5 hours overnight | Taiwan Navigation's Penghu ferry. The day sailing leaves Kaohsiung at 09:00 and arrives about 13:30. The night sailing leaves at 23:30 and arrives about 06:00, and the ship has sleeper cabins. It does not sail every day: the operator's monthly timetable lists the sailing days. |
| Budai to Magong (Penghu) | about 100 minutes | Taiji Star fast catamaran, summer only. The operator suspends the route for winter, and its 2026 notice gives 12 October as the start of the suspension. |
What helps on this crossing
- Pick your season with care. Taiji Star's Budai boats stop for winter because of sea conditions, so a winter crossing means the larger Kaohsiung ship.
- Use the night sailing to lie flat. The ship leaves Kaohsiung at 23:30, arrives about 06:00 and has sleeper cabins, and the operator says arrival times move with the weather.
- Check the operator's notice before you travel. The Penghu ferry's site says sailing times follow the weather, and it refunds tickets in full within 30 days when weather stops a sailing.
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 Taiwan Strait rough in January?
January is one of the roughest months. Wave reanalysis data (ERA5) puts the mean daily maximum wave height near Penghu at about 2.6 m, and 49% of January days are above the annual 75th percentile there. The Penghu ferry's operator names the northeast monsoon as the season when sea conditions limit lighter boats.
Is the Taiwan Strait rough in July?
July is one of the calmer months, with about 1.1 m mean daily maximum wave height near Penghu and 5% of days above the annual 75th percentile. The Budai to Magong fast boats run in summer.
Is the Taiwan Strait rough in October?
October is the turning point. The mean daily maximum wave height near Penghu is about 2.4 m and 39% of days are above the annual 75th percentile. Taiji Star's 2026 notice suspends the Budai to Magong boats from 12 October.
Do the Penghu ferries run in winter?
The Kaohsiung to Magong ferry does, on a timetable the operator publishes by month. The Budai to Magong fast boats do not run in winter.
Other crossings
Sources & further reading
- https://en.wikipedia.org/wiki/Taiwan_Strait
- https://tnc-kao.com.tw/about/about
- https://tnc-kao.com.tw/question
- https://tnc-kao.com.tw/schedule/timetable
- http://www.taijistar.com.tw/schedule.php
- http://www.taijistar.com.tw/info.html
- http://www.taijistar.com.tw/index_eng.html
- https://www.penghu-nsa.gov.tw/ChiHoOneLer/transport/Traffic/Traffic/ship01.htm
- https://open-meteo.com/en/docs/marine-weather-api
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.