My travel mate has a big problem when we are traveling together. He gets travel sick very fast. Obviously there are medicament which you can take to avoid it, but aren't there any other ways to avoid getting travel sick?
On a boat I know that it is good to focus on a thing that is not moving like to boat, but on the ocean, where you can only see water, it is kind of difficult. On the train you can try to sit in the direction of motion, but this does not always help. In the car it helps to sit in the front, or drive by yourself, but is also not always possible. In a plane I don't know any useful tip.
So my question is, what are useful tricks and tips to avoid getting travel sick in various vehicles, such as planes, trains, ships, cars, coaches or even elephants or camels.