Is the Portsmouth to Santander crossing rough?
In season, yes, this is one of Europe's famously lively crossings. Portsmouth to Santander runs about 32 to 33 hours with Brittany Ferries and crosses the open Bay of Biscay end to end, water with a reputation earned over centuries. Summer sailings are frequently calm and pleasant; between October and March the bay regularly reminds passengers why the reputation exists.
English Channel and Bay of Biscay · about 32 to 33 hours · Reputation among passengers: has a long-standing reputation for rough passages.
- Low
- Moderate
- High
- Very high
Roughness summarises typical reported conditions on this route, not a forecast for any given sailing.
Atlantic swell over a shoaling shelf
Key facts
- The Portsmouth to Santander crossing takes about 32 to 33 hours, operated by Brittany Ferries.
- It crosses the English Channel and Bay of Biscay, and passenger reports place the route in the high roughness band.
- What drives the rough days: Atlantic swell over a shoaling shelf.
- Conditions are reported roughest in January, February, November and December.
- The calmest months are usually June, July and August.
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Why the Portsmouth to Santander crossing gets rough
The Bay of Biscay is open to the west, so swell from mid-Atlantic storms arrives with thousands of miles of fetch behind it, then hits the continental shelf where the seabed climbs from over 4,000 m to under 200 m. Shoaling waves slow, shorten and steepen. Add wind waves from a passing depression and you get the confused, cross-running sea Biscay is known for. This route spends a full day in exactly that water.
This route crosses the Bay of Biscay. For the full picture of that water, every crossing on it and what drives its reputation, see is the Bay of Biscay rough?
When it's worst, month by month
Roughest October to March, when Atlantic depressions run across the bay one after another. Calmest late May to August under the Azores high. September is the turning point: often mild, but the first autumn lows can arrive with little warning. The route sails all year, up to twice a week, with fewer sailings in winter.
| 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Roughest | Roughest | Rough | Mixed | Mixed | Calm | Calm | Calm | Mixed | Rough | Roughest | 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: 32 to 33 hours
Roughest stretch: Mid-passage, once clear of the French shelf edge
A midship cabin on a low deck is the whole game on a two-night crossing. Motion grows with every deck of height and every metre towards bow or stern.
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What helps on this crossing
- Book a midship cabin low in the ship the day you book the ferry; the good ones go first.
- Check the Met Office shipping forecast for Plymouth, Biscay and FitzRoy the day before sailing.
- Plan flexible meals rather than fixed sittings; appetite comes and goes with the sea state.
- Spend part of the open-water day where you can see the horizon rather than in a windowless corner.
- If your dates can move at all, a June sailing and a November sailing are different propositions.
Buying a tablet in the UK before you sail? UK pharmacies sell Kwells, Stugeron and Avomine for travel sickness, and their labels differ on when to take them. Kwells vs Stugeron and Stugeron vs Avomine set out the label facts side by side. Which one suits you is a question for the pharmacist.
For the full toolkit see the seasickness guide, or what to do once it has already started. Choosing between a fast catamaran and a conventional ship elsewhere too? The physics is the same everywhere: see the catamaran guide. If the rocking follows you ashore afterwards, that is land sickness, which is normal, and it passes.
Frequently asked questions
Is the Portsmouth to Santander ferry always rough?
No. The reputation is built on autumn and winter crossings. June to August sailings are frequently calm enough to be unremarkable, and many passengers cross without noticing the bay at all. The variability is the point: the same route can be flat in July and heavy in November, so the forecast for your dates matters more than the route's name.
How long does the crossing take, and how much is open water?
About 32 to 33 hours dock to dock. After the Channel leg, the ship spends roughly a full day crossing the open bay, including the stretch over the shelf edge where the sea steepens most. There are two nights aboard on the standard schedule.
Where should I sleep on the ship?
As close to the middle of the ship as possible, and as low as possible. A ship rotates around a point near its centre, so bow and stern cabins travel the largest vertical arcs and high decks swing furthest. On this route the difference between a good cabin and a bad one is not subtle.
Should I take seasickness medication for Biscay?
That is a pharmacist's or doctor's question, and worth asking before this particular crossing rather than after boarding. Note when you ask that most motion sickness medicines are labelled to be taken before sailing, and that this route involves two nights at sea, which affects what makes sense.
Other ferry routes
Sources & further reading
- https://en.wikipedia.org/wiki/Bay_of_Biscay
- https://www.brittany-ferries.co.uk/ferry-routes/ferries-spain/portsmouth-santander/timetable
- https://ferrygogo.co.uk/spain/portsmouth-santander/
- https://www.brittany-ferries.co.uk/ferry-routes/ferries-spain/portsmouth-santander
- https://www.directferries.com/portsmouth_santander_ferry.htm
Your next question, probably
Where on the ship should you be?
Which cabins move least, and what to do if you already booked one
If that is not your question:
Conditions described here are typical patterns drawn from published marine and operator information as of September 2026, not a forecast: any month can deliver a calm crossing or a bad one, and schedules, vessels and operators change. Route, vessel 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.