Some people get ther"sea legs" after only a few hours. But I've seen some who stay sick the entire cruise and have to spend the whole week in bed. I suggest buying some over the counter patchs before you go. You DON"T want to visit the ship's doctor, if you think the cruise cost you, wait till you get the medical bill!!!!!!!!!!! But really these ships don't rock and roll much and most of the time you will swear your walking around a large land resort. The captain goes out of his way to avoid stormy weather, since sick people wont buy those overprised drinks or spend time in the shops or casino.