After motion sickness begins, it usually doesn't start getting better until you stop moving. But, most people who are on a boat for a long trip feel better a few days into the trip when they get used to being on the boat, but some people feel seasick for several days.

For most people, the acute symptoms of seasickness—such as nausea, dizziness, and cold sweats—will typically last between 12 to 48 hours. This period represents the time it takes for the brain's vestibular system to achieve "habituation" or "sea legs," where it finally adapts to the constant motion of the vessel. Once the body acclimates to the environment, the symptoms usually dissipate entirely, even if the sea remains rough. If the sickness is caused by a short trip, the symptoms generally vanish within a few hours of returning to stable land. However, some individuals experience a secondary condition known as Mal de Debarquement Syndrome (MdDS), or "land sickness." In these cases, the sensation of rocking or swaying can persist for several days, and in rare, chronic instances, even months after disembarking. To minimize the duration of the initial sickness, it is recommended to stay hydrated, spend time on the deck looking at the horizon, and avoid heavy or greasy foods. Most modern cruise ships are equipped with advanced stabilizers that significantly reduce motion, often preventing the onset of seasickness for all but the most sensitive passengers.