- Seasickness comes from a mismatch between what your eyes see and what your inner ear feels, and it is far easier to prevent than to stop.
- A catamaran rolls much less than a single-hull boat, and the middle of any boat moves the least.
- Mornings are often calmer than afternoons, when the wind tends to build, so an early start helps sensitive guests.
- Motion sickness tablets work best when taken before you board, not once you already feel sick.
- From about November to January the north-east monsoon can make the Gulf of Thailand rough, and routes may change or trips be postponed.
It is the evening before your boat day, and someone in your group says it quietly: "I get seasick. Will I spend the whole trip hanging over the rail?" It is a fair question, and the honest answer is that with the right boat, the right seat and a bit of preparation, most people are fine.
This guide is about seasickness on a boat trip around Koh Samui: why it happens, how to choose a steadier boat, where to sit, what to eat and take, and what to do on board if the queasy feeling starts. It is also honest about the days when the sea is simply choppy, because those happen too.
Why do people get seasick on a boat trip?
Seasickness happens when your eyes and your inner ear disagree. Your balance system feels the boat rising and rolling, while your eyes, fixed on the deck, a phone or a cabin wall, tell your brain that nothing is moving.
The brain does not like mixed signals. The result is the familiar chain: yawning, a cold sweat, a pale face, a heavy head and then nausea. Some people feel it within minutes, others only after hours of steady rolling.
Not everyone is equally sensitive. Children above toddler age, people who get carsick, and anyone who is tired, hungover or dehydrated tend to suffer more. Experienced sailors get seasick too, they have just learned the tricks to keep it away.
The good news is that the sea around Koh Samui is a gulf, not an ocean. On a normal day in the calm months the water between the islands is gentle, and many guests who fear the worst barely notice the motion. The trouble days are windy ones, and those are what you plan for.
Which boats are steadier: catamaran, speedboat or junk?
The steadiest choice for a sensitive group is a catamaran. With two hulls set wide apart, it rolls far less from side to side than a single-hull boat, and the motion it does have is slower and easier on the stomach.
Sailing catamarans like Victoria, Nina, Vickey, Scarlet and the Lagoon 400 Blue Coco are the usual choice for families and groups who care about comfort more than speed. You can read more on the page about renting a catamaran on Koh Samui.
Speedboats are a different experience. They spend much less time at sea because they get there fast, but on a choppy day they bounce over the waves and every hit is felt. On a calm day a good speedboat is perfectly comfortable, and the short crossing can actually be an advantage: less time on the water means less time for the stomach to complain.
The big sailing junk Red Baron, 30 m (98 ft) long, moves slowly and heavily, which many people find gentle. Long-tail boats are small and open: lovely on a flat morning close to the coast, less so when the wind picks up.
| Boat type | How it moves | Best for sensitive guests |
|---|---|---|
| Sailing catamaran | Two hulls, little rolling, slow and steady | Yes, the safest bet |
| Sailing junk (Red Baron) | Long, heavy, unhurried | Good on short cruises and sunset trips |
| Speedboat | Fast, short crossings, bumps in waves | Fine on calm days, sit in the middle |
| Motor yacht | Heavier than a speedboat, more shelter | Comfortable, but cabins can be stuffy |
| Long-tail boat | Small and open, close to the water | Only for short trips on flat mornings |
For a full side-by-side look at the two most popular options, read catamaran or speedboat on Koh Samui.
Where is the best place to sit to avoid seasickness?
Sit in the middle of the boat, low down and outside, with a clear view of the horizon. The middle moves the least, the bow moves the most, and fresh air helps far more than a cool cabin.
Think of a boat like a seesaw. The ends go up and down, the centre barely moves. On a speedboat that means avoiding the front cushions on a choppy crossing, even though they look like the best seats in the photos. Save them for the anchorage.
Facing forward helps too, so your eyes see the direction of travel and your brain can predict the motion. Sitting backwards, or sideways and looking at the deck, is a quick way to feel worse.
The worst place for a sensitive stomach is usually below deck. Going inside to lie down in a cabin, without a view of the sea, makes the eye and ear mismatch stronger. If you need a break, find a shaded spot outside where you can still see the horizon.
- Do: sit in the middle, low, facing forward, with the horizon in view.
- Do: stay in the fresh air and the shade.
- Avoid: the bow on a choppy crossing.
- Avoid: reading, scrolling or watching videos while the boat is moving.
- Avoid: standing near engine fumes at the stern.
Is the sea calmer in the morning or the afternoon?
Around Koh Samui the sea is often calmer in the morning, and the wind tends to build during the day. That is a general pattern, not a rule, but it is why early starts are kinder to sensitive stomachs.
On a full-day trip, the crossing out in the morning is usually the smoother one, and the ride home in the afternoon can be bumpier. If you are sensitive, take that into account when you plan how much to eat and drink at lunch.
The season matters even more than the hour. From about November to January the north-east monsoon can make the sea on the Gulf of Thailand rough. On those days trips may change route or be postponed, and the captain makes the final call. Ang Thong National Marine Park is usually closed every year from 1 November to 15 December, so no Ang Thong trips run then anyway.
For the full picture month by month, see the guide to the best time for a boat trip on Koh Samui. Outside the monsoon, many days are calm enough that seasickness is a non-issue for most people.
Which route is easiest on a sensitive stomach?
The shorter the crossing, the easier the day. Koh Tan and Koh Madsum, the Pig Island, lie just off the south coast of Koh Samui, and Koh Phangan is about thirty minutes away, so these are the gentlest choices.
Longer days to Ang Thong Marine Park or to Koh Tao and Koh Nang Yuan mean more time in open water. They are wonderful trips, but if someone in your group is really prone to seasickness, I would not pick them for your first day at sea. Start short, see how everyone feels, then go further.
A half day or a sunset cruise is another way to keep the time at sea short. Victoria runs a 2.5-hour sunset cruise to Koh Tan for ฿21,000 and a 4-hour trip to Koh Madsum and Koh Tan for ฿25,000. Nina runs a 2.5-hour sunset cruise for ฿22,000, and the Red Baron starts at ฿42,000 for a 3-hour sunset dinner cruise.
Budget groups can even take a long-tail from Thong Krut Pier: a 4-hour trip to Koh Tan and Koh Madsum costs from ฿3,000 for 1-2 people. It is a small, open boat, so keep it for a calm morning. The page on boat trips to Koh Tan and Koh Madsum lists all the boats on this short route.
Tablets, food and drink: what actually helps?
If you know you get seasick, take a motion sickness tablet before you board, following the packet or a pharmacist's advice. Taken after the nausea has started, tablets work much less well.
Motion sickness tablets are easy to find in pharmacies on Koh Samui. Some types make you drowsy, which is not always a bad thing on a boat, but avoid alcohol with them. If you take other medicines, are pregnant or are giving tablets to a child, ask the pharmacist which one is right.
Food makes a real difference. An empty stomach and a heavy, greasy breakfast are both bad ideas. The sweet spot is a light breakfast a little while before pickup: toast, rice, a banana, some plain crackers.
- Sleep well the night before, and skip the late party.
- Eat a light breakfast, not nothing and not a feast.
- Drink water through the day, little and often.
- Go easy on alcohol, especially before the ride home.
- Bring ginger: sweets, biscuits or tea. Many people find it helps.
- Pack plain snacks for the trip, like crackers or fruit.
- Wear sunglasses and a hat: glare and heat make nausea worse.
- Take the tablet in time, if you use one.
Some people swear by acupressure wristbands. The evidence is mixed, but they are harmless, and if they make you feel more in control, that alone can help.
What to do on board if you start to feel sick
Act at the first yawn or cold sweat, not when you are already pale. Move to the middle of the boat, sit low, look at the horizon and breathe slowly through your nose.
Tell the crew. They have seen it hundreds of times, and there is nothing embarrassing about it. They can bring water, help you to a better seat and sometimes adjust the speed or the angle to the waves to make the ride smoother.
Getting into the water at the next stop often helps more than anything else. Floating in calm water, with a life jacket if you are unsure, resets the balance system surprisingly well. Many guests who felt awful on the crossing are laughing again after a few minutes of snorkelling.
If you do get sick, go to the side the crew points to, away from the wind, and hold on firmly. Afterwards, rinse your mouth, sip water and nibble something dry. Most people feel much better soon after.
Which boat should a seasick-prone group book?
For guests who are really sensitive, a sailing catamaran on a short route is my first choice. For groups who want speed and a full day, the Pearl speedboat is the one I recommend most, booked on a calm-season date and with everyone sitting in the middle.
Whichever boat you choose, tell the manager about the sensitive guests when you send the request. It changes the advice you get on the route and the timing, and it costs nothing to mention.
Pearl is a 12 m (38 ft) speedboat with two 200 hp Suzuki engines for up to 15 guests. Its 8-hour trips cost ฿38,000 to Koh Tan and Koh Madsum or around Koh Phangan, ฿39,000 around Koh Samui or to Ang Thong Marine Park, and ฿41,000 to Koh Tao with Koh Nang Yuan, with hotel transfer included. Its short crossings to Koh Tan and Koh Phangan are a good match for sensitive guests, and the details are on the Pearl speedboat page.
Pearl suits groups who want a full day with plenty of stops, Victoria and Nina suit families and nervous guests on short catamaran trips, and the Red Baron suits groups who want a slow, heavy boat for a sunset cruise.
Quick checklist before your boat day
Run through this the evening before, and you have done most of what can be done.
- Pick a steady boat and a short route for anyone who is sensitive.
- Choose a morning start if you can.
- Check the season: from about November to January the sea can be rough.
- Buy tablets in advance and take them before boarding.
- Pack water, ginger, plain snacks, a hat and sunglasses.
- Claim a seat in the middle, outside, facing forward.
Questions and answers
Can children get seasick on a boat trip in Koh Samui?
Yes, children can get seasick, often more easily than adults. Keep them in the middle of the boat, outside and busy looking at the sea rather than a tablet screen. If you want to give them motion sickness medicine, ask a pharmacist for a child-safe option and the right dose.
Does seasickness go away on its own?
For most people it eases soon after the boat stops moving or once they are in the water at a swim stop. On long crossings some people get used to the motion after a while. It rarely lasts long once you are back on land.
Is it better to go on a boat trip with an empty stomach?
No, an empty stomach usually makes nausea worse. Eat a light, plain breakfast before pickup and skip anything heavy, greasy or spicy. Keep sipping water and nibble plain snacks during the day.
Should I go into the cabin to lie down if I feel sick?
Usually not. Without a view of the horizon, the mismatch between your eyes and your inner ear gets stronger. A shaded seat in the middle of the deck with fresh air is a much better place to recover.
Can I cancel if the sea looks rough on the day?
The captain decides whether it is safe to go and may change the route or postpone the trip. Ask the manager on WhatsApp what the options are for your boat and date when you confirm the booking. Booking early in your holiday leaves room to move the day if needed.
Do motion sickness tablets make you sleepy?
Some types do, others much less. If you want to stay alert for snorkelling, ask the pharmacist for a non-drowsy option. Do not mix them with alcohol, and follow the packet for timing.
Is a sunset cruise a good idea for someone who gets seasick?
Often yes, because it is short and usually stays close to the coast. Choose a catamaran or the big sailing junk, sit in the middle and keep the drinks light. If the evening is windy, the captain may keep the route sheltered or suggest another day.
Ready to choose your boat?
Every boat page shows the routes, prices and what is included. The booking request is free: a manager checks the boat is free on your date and confirms the price.
Updated 10 November 2026. Prices can change: the boat page always shows the current price.
