Drink plenty of water and avoid heavy foods. Still you need to keep an eye on your blood sugar. Instead snack light things like crackers, fruit, or ginger candy, known for calming upset stomachs.

2. Look at the Horizon

Focusing on a fixed point on the horizon can help stabilize your senses and reduce feelings of nausea.
Try to avoid looking at moving objects or reading while on the ferry.
Stepping outside for fresh air can also help distract you and make you feel better.

3. Medicine

Get yourself some otc-medication. Having it with you already gives you a feeling of comfort.
In the pharmacy they can help you find what helps in your occasion. Don’t forget to check if you need to take it beforehand or later.
Most common is probably ginger pills. For decades, sailors and seafarers have relied on ginger medication to combat seasickness.
It is known for its anti-nausea properties and ability to soothe upset stomachs.
If you need stronger medication or you take other medication, make sure to always to talk to a doctor first.

4. Stay Occupied

Distraction is the key to make time go by. Keep yourself occupied during the journey with activities that distract your mind from feeling sick. Bring along a book, listen to music, or engage in light conversation with your travel companions.
Many ferrys also have an extra room in case you need to lie down and rest in a quiet room.

5. Pick the Right Spot

Sit in the middle where the boat is said to moves the least. Picking a seat near the waterline can also help reduce rocking.